CYCADOPHYTAN FRONDS.
Occasional reference is made to Cycadean fronds in the account of
flowers and stems but it is seldom that genera or species founded
on leaves can be definitely correlated with particular types of
reproductive organs or stems. As in the case of Ferns and Pteridosperms
so also with detached leaves believed to be Cycadean, a large number
of generic names have been employed for impressions which afford no
information with regard to anatomical characters except, in some
of the more favourably preserved specimens, a few facts as to the
epidermal cells. Though association often suggests original connexion
it is inadvisable except in well established cases to extend to fronds
generic terms based on reproductive shoots. The designation _Zamites_
has long been used for fronds that are clearly not closely related to
recent species of _Zamia_, and were it not an old established genus
the significance of which is not likely to be misunderstood, it would
be wiser to substitute for it some name implying no affinity with
any existing type. On the other hand the employment by some authors
of such generic names as _Encephalartos_ and _Ceratozamia_ is not
warranted by the evidence furnished by the imperfect material. Prof.
Newberry[1424] described as _Encephalartos_? _denticulatus_ a piece
of a frond from Rhaetic beds in Honduras characterised by lanceolate
pinnae (30 × 6 mm.) gradually narrowed towards the acute apex and
abruptly contracted at the base: the method of attachment of the pinnae
appears to agree with that in the genus _Zamites_. In this case there
is no valid reason for assuming a relationship with _Encephalartos_
or with any recent type. An impression from Lower Cretaceous, Dakota,
beds in Kansas described as _Encephalartos cretaceus_ Knowlt. ex Lesq.
ms.[1425] consists of a piece of lamina, 9 × 4 cm., obovate-oblong and
with a cuneate base, a serrate margin and thick diverging veins: the
specimen is too incomplete to serve as a record of any Cycadean genus.
The generic name _Encephalartopsis_ was applied by Fontaine[1426]
to some imperfect pinnae from the Potomac beds characterised by a
linear-elliptical lamina with a spinous margin and slightly diverging
and occasionally anastomosing veins. The figured examples of the
type-species, _E. nervosa_, suggest pinnae like those of _Ctenis_; but
in the absence of a rachis the method of attachment of the segments
cannot be ascertained. Saporta[1427] named a specimen from the Miocene
flora of Koumi, Greece, _Encephalartos Gorceixianus_ because of its
resemblance in habit to some species of the recent genus; but the
designation _Zamites_ would be more appropriate. Ettingshausen recorded
an imperfect impression of a pinna from Tertiary rocks in Styria as
_Ceratozamia Hofmanni_[1428] although it is by no means certain that
the fragment is even Cycadean. The genus _Taeniopteris_ was described
in the second volume of this book as probably a Pteridophyte, though
of uncertain systematic position: it has, however, been shown by
Mr Thomas[1429] that the Jurassic species _T. vittata_ was almost
certainly borne on a stem with reproductive organs constructed on the
Bennettitalean plan. Further research may enable us to fix the position
of other species but as yet _T. vittata_ is the only representative of
the genus which there is good reason for assigning to the Bennettitales.
It is undoubtedly true that Cycadean plants, using the term in a wide
sense to include the Bennettitales as well as the Cycadales, bulked
largely in Upper Triassic, Rhaetic, Jurassic-Wealden floras; the
Bennettitales probably reached their maximum development as regards
wealth of form and geographical range in the latter part of the
Jurassic period and in the earliest phase of the Cretaceous epoch. In
Triassic floras Cycadean plants are represented almost solely by fronds
but the very close resemblance between Keuper species and forms that
in Jurassic rocks are found in association with fertile shoots leaves
little doubt as to the affinity of Keuper and Rhaetic species.
The evidence obtained from Permo-Carboniferous strata is much more
meagre, at least as regards Cycadean leaves: the occurrence of certain
morphological Cycadean features is revealed by petrified vegetative
organs of Palaeozoic plants, and the Cycadean plan of organisation is
conspicuous in many Carboniferous and Permian seeds. The discovery
of frond-impressions identical in external characters with Mesozoic
genera may be accepted as a substantial indication that genera already
existed possessing foliage of the Cycadean type, though we have no
certain information with regard to the nature of the other organs of
the parent-plants. A few examples of Palaeozoic species are included
among those selected in illustration of the different genera, namely
_Plagiozamites Planchardi_, _Sphenozamites Rochei_, _Pterophyllum
Fayoli_, _P. Cambryi_: among other recorded instances of Palaeozoic
species are _Pterophyllum Cottaeanum_ Gutb.[1430], a Permian type
similar in habit to _Ctenis_ but without anastomosing veins, a
feature in which it resembles _Pseudoctenis_; the Carboniferous
species _Pterophyllum inflexum_ Eich.[1431] from the Altai mountains,
transferred by Zeiller to _Dioonites_; _P. blechnoides_ Sand.[1432]
from the Stephanian of Oppenau; _Pterophyllum Grand’Euryanum_[1433]
from Upper Carboniferous beds in France, and _P. gonorrachis_
Goepp.[1434] from Silesia. An examination of the type-specimens of the
Carboniferous species _Cycadites gyrosus_ Goepp. and _C. taxodinus_
Goepp.[1435] in the Breslau Museum led me to regard the material as too
imperfect to determine.
A conclusion that is forced upon us by a consideration of the
geological range of Cycadean fronds is that at the close of the
Wealden period, a period very closely linked in the character of
the vegetation with the preceding Jurassic floras, there appears
to have been a relatively sudden decrease in the number of members
of the Cycadophyta: the decline in the fortunes of Cycadean plants
is coincident with the rise and remarkably rapid extension of the
Angiosperms. From Middle and Upper Cretaceous and from Tertiary beds
very few Cycadean remains have been obtained and many of them are
represented by fragmentary fossils that afford no definite evidence
of affinity to recent genera. The antiquity of the Cycadales, that
is the section represented by existing Cycads, cannot be determined;
but it would seem probable that if the Cycads apart from the
Bennettitales existed in Jurassic and Lower Cretaceous floras they
occupied a very subordinate position in comparison with the extinct
Bennettitales. There are no data pointing to any widespread occurrence
of the Cycadales in the Northern Hemisphere in Tertiary times at all
comparable with the geographical range of Tertiary ancestors of the
solitary survivor of the Ginkgoales.
The following records of Tertiary Cycadean fronds illustrate
the paucity of the records. Reference has already been made to
_Encephalartos Gorceixianus_ Sap. of Miocene age, a species that has
no claim to be regarded as an example of the recent South African
genus. The specimen described by Saporta and Marion as ? _Zamites
palaeocenicus_[1436] from the Eocene of Gelinden is too imperfect to
serve as a trustworthy record. A more satisfactory species, similar in
habit to _Zamites gigas_, is that on which Saporta founded the species
_Zamites epibius_[1437] from Lower Miocene beds at Bonnieux (Vaucluse),
France. Another Tertiary species is mentioned by Krasser[1438] from
Pliocene strata in Brazil as _Zamia praecedens_ Krass. ex Ett.
+MS.+ Ettingshausen has described a Tertiary species from New South
Wales, either Lower Miocene or Upper Eocene in age, as _Anomozamites
Muelleri_[1439], characterised by truncate segments with simple veins
and set obliquely to the rachis.
While certain form-genera of fronds can only be referred to the
Cycadophyta, in other cases it is possible to assign fronds to a
section of this comprehensive group characterised by a particular type
of fertile shoot and by certain well defined epidermal features.
The investigation of the cuticular structure of various Cycadean fronds
by Nathorst[1440] and especially by Mr Thomas[1441] has supplied a
basis of classification which affords the best criterion of affinity so
far available. The majority of fronds are placed in the Bennettitales
while the three genera _Ctenis_, _Nilssonia_, and _Ctenopteris_ (or
_Ptilozamites_[1442]) are placed in the Nilssoniales.
I. =Bennettitales.= Epidermal cells characterised by sinuous walls and
generally rectangular; the cuticle is thin; the stomata, confined to
the lower surface of the pinnae, tend to be arranged at right-angles
to the veins and are on a level with the epidermis or very slightly
depressed; two large laterally placed subsidiary cells more or less
surround the guard-cells and these are provided with thickenings of a
definite shape (figs. 594, 609).
Genera: _Ptilophyllum_, _Zamites_, _Otozamites_, _Dictyozamites_,
_Pterophyllum_ and _Anomozamites_, _Taeniopteris_, _Pseudocycas_.
II. =Nilssoniales.= Epidermal cells with straight walls, not sinuous,
irregular in form, rounded, hexagonal, or rectangular; the stomata are
below the level of the epidermis; the cuticle may be thin or thick.
There is no regular arrangement of the stomata; the guard-cells are
surrounded by 6–8 subsidiary cells (fig. 625) which often form an
overarching canopy; thickening lamellae like those on the guard-cells
of the Bennettitales are seldom present.
Genera: _Nilssonia_, _Ctenis_, _Ctenopteris_.
It is a noteworthy fact that the representatives of the smaller group,
the Nilssoniales, in their cuticular features, are more akin than the
Bennettitales to modern Cycads. Until definite evidence is obtained as
to the nature of the reproductive organs of _Nilssonia_, _Ctenis_, and
_Ctenopteris_ it is impossible to say how closely these genera agree
in essential characters with existing members of the Cycadales. If, as
has been suggested, the fertile shoots known as _Beania_[1444] belong
to _Nilssonia_ their resemblance in plan of construction to the cones
of recent genera, much greater than in the case of the flowers of the
Bennettitales, is in accordance with the evidence of the epidermal
characters.
Reference was made in the second Volume of this book to several genera
founded on fronds which through lack of evidence as to the nature of
the reproductive organs cannot be assigned with certainty either to
Ferns or Cycads: it was stated that the genera _Ptilozamites_ and
_Ctenopteris_ are probably Cycadean, and the structure of the epidermal
cells in the latter genus lends support to this view[1445]. Among other
genera of doubtful position not included in the following descriptions
of fronds is _Zamiopsis_ of Fontaine[1446] founded on large compound
fronds from the Potomac formation: the venation and form of the pinnae
are more Fern-like than in _Ctenopteris_, but in general habit the
two genera are not very dissimilar. The generic name Zamiopsis is
misleading as the species bear no resemblance to _Zamia_ or _Zamites_.
+I. Bennettitales.+
=PTILOPHYLLUM.= Morris.
The generic name _Ptilophyllum_ was instituted in 1840 for some
specimens of pinnate fronds from Cutch: in this genus Morris[1447]
included with the Indian leaves the English Jurassic species
_Pterophyllum pecten_ Lind. and Hutt.[1448] (figs. 587, etc.) and
some other forms. He defined _Ptilophyllum_ as follows: ‘Fronds
pinnate; pinnae closely approximated, linear, lanceolate, more or
less elongate, imbricate at the base, attached obliquely; base
semicircular or rounded; veins equal, slender, parallel.’ Morris adds
that he instituted a new genus in preference to _Zamites_ because
of the ‘oblique insertion of the pinnae and their overlapping each
other at the base.’ In a later paper Morris[1449] states that the
pinnae of _Ptilophyllum_ fronds are ‘sometimes auriculed in the upper
and sometimes in the lower part’ of the base of the lamina. In his
catalogue[1450] he adopted Endlicher’s genus _Palaeozamia_ instead of
_Ptilophyllum_. Without discussing the generic nomenclature adopted
by various authors for the Indian types and similar fronds it is
important to refer briefly to the treatment of Morris’s species by
Oldham and Morris and by Feistmantel. In the first of the series of
Memoirs on Gondwana floras[1451] _Ptilophyllum_ is retained for a
section of _Palaeozamia_ together with _Otozamites_ and _Sphenozamites_
as other sectional subdivisions: in the subgenus _Ptilophyllum_ are
included _Palaeozamia acutifolia_ and _P. cutchensis_ (fig. 588, A,
C), also _P. affinis_, _P. rigida_, and _P. bengalensis_. The last
species is in all probability an _Otozamites_: _P. affinis_ and _P.
rigida_ are almost certainly indistinguishable from _P. cutchensis_.
Feistmantel[1452] dealt in detail with the genus _Ptilophyllum_: he
wrote, ‘with Schimper and Schenk I therefore look upon this genus
as an Indian type especially characterised by its ... more or less
slender leaves, angustate towards the apex and base, and petiolate,
with regularly adfixed leaflets.... The leaflets are equal to each
other, for the most part elongate linear, and _auriculate and free
at the upper angle at the base_, but adfixed at the lower angle, and
each is decurrent behind the upper angle of the leaflet next below it,
thus the leaflets are almost imbricate. The veins are rather numerous,
simple, and forked, and more or less divergent[1453].’ Feistmantel
distinguishes certain varieties of _P. cutchense_ (fig. 588, A, C),
none of which appear to be well defined. A specimen from the Rajmahal
Hills with unusually long pinnae, the frond having a breadth of 8 cm.,
is described as _Ptilophyllum acutifolium_ var. _maximum_[1454], but
it differs in no important feature from the smaller and commoner form.
The next point to be considered is the variability of certain species
referred by Feistmantel to _Otozamites_. He figures specimens from the
Jabalpur group as _O. Hislopi_ Feist. ex Old. +MS.+, _O. gracilis_
(Kurr), _O. angustatus_ Feist. (fig. 588, B) and _O. distans_[1455]. An
examination of the figured specimens leads me to regard _O. Hislopi_
and _O. gracilis_ as identical with the _Ptilophyllum_ fronds: the
pinnae exhibit no distinguishing features and there is no reason for
a specific, still less a generic, separation. _Otozamites angustatus_
is indistinguishable from _Otozamites_ sp. as figured from the
Madras coast and from _Ptilophyllum cutchense_, _P. cutchense_ var.
_curvifolium_ and var. _minimum_. The drawings reproduced in fig. 6_a_,
Pl. +x.+ of the Madras flora[1456] and in fig. 8_a_, Pl. +vi.+ of the
Jabalpur flora[1457] showing auriculate bases are inaccurate: in all
the fronds named the pinnae are straight with rounded edges precisely
as in _Ptilophyllum_. The conclusion forced upon me by a comparison
of the actual specimens is that the Indian fronds are not separable
into well-defined species and should all be included in _Ptilophyllum
cutchense_. Moreover in this comprehensive species should be included
the specimens described by Feistmantel as _Otozamites Hislopi_ (fig.
589), _O. angustatus_, and _O. gracilis_. It may well be that a more
detailed investigation of the numerous forms comprised in this protean
species, particularly if specimens are obtained from which cuticular
preparations can be made, may lead to the recognition of additional
species or well-defined varieties. The resemblance between the various
forms of _P. pecten_ from the Jurassic strata of Yorkshire and those
of _P. cutchense_ from India is very striking, and at least in many
cases no specific separation is possible so far at least as the form of
the fronds and pinnae is concerned. The occasional close association
of _Ptilophyllum_ fronds and _Williamsonia_ flowers is an important
agreement between the English and Indian fronds (fig. 590).
[Illustration: Fig. 587. _Ptilophyllum pecten._ (British Museum, V.
3795; ¼ nat. size.)]
[Illustration: Fig. 588. _Ptilophyllum pecten._ A, C, specimens
figured by Feistmantel as _Ptilophyllum cutchense_. B, Feistmantel’s
_Otozamites angustatus_. (⅚ nat. size; Calcutta Museum.)]
[Illustration: Fig. 589. _Ptilophyllum pecten._ A frond figured by
Feistmantel as _Otozamites Hislopi_. A, ⅚ nat. size; B, enlarged
(Calcutta Museum).]
In the first part of the Catalogue of Jurassic plants from Yorkshire
the opinion was expressed[1458], based on an examination of Morris’s
type-specimen of _Ptilophyllum cutchense_ and of a large number
of English and other fronds identical with or closely allied to
_Pterophyllum pecten_ Lind. and Hutt., that the Indian and European
fronds belong to the same genus. In a later paper[1459] it was
maintained that _P. cutchense_ and _P. acutifolium_ are probably
identical with the English type, and a drawing was published—reproduced
in fig. 591—of Morris’s type-specimen. Dr Halle[1460] has discussed
the genus _Ptilophyllum_ and his investigations lead him to a
different conclusion; he, like Zeiller and some other authors, employs
_Ptilophyllum_ in Feistmantel’s sense. The pinna-base is said to agree
in its asymmetrical form with that in _Otozamites_, while it differs
from the symmetrical base of _Zamites_ pinnae. In _Ptilophyllum_ both
edges of the pinna-base are said to bend down in joining the rachis; at
the upper corner the base thus becomes rounded and for some distance
free from the rachis; it is also sometimes a little auriculate; at the
lower edge the pinna is decurrent on the upper surface of the rachis.
In a subsequent paper Halle[1461] repeats the view that the decurrence
of the pinnae by their lower edges is an important distinguishing
feature of _Ptilophyllum_, thus agreeing with Feistmantel whose
illustrations appear to be confirmatory. The drawings in Feistmantel’s
memoirs are, however, misleading and in some cases incorrect. An
examination of a photograph of Morris’s type-specimen of _P. cutchense_
led Halle to conclude that the two edges of the pinna-base bend
downwards on joining the rachis as described by Feistmantel. This
feature is not shown in the drawing reproduced in fig. 591: it is
clear that either the drawing is incorrect or that there has been some
mistake in the interpretation of the photograph. Through the courtesy
of Dr Halle I have been able to examine the actual print: when viewed
in its correct position the two edges of the pinnae appear to bend
down as described by Halle, but if it is examined in the reverse
position the lower angle of the pinnae is seen to be slightly rounded
as in fig. 591, the apparent decurrence being due to a confusion
between the appressed lower edge of one pinna, which is faintly shown,
and the stronger downward trend of the upper edge of the pinna next
below. The upper edges of the pinnae are more prominent because they
are less appressed to the rachis while the lower half of the base
is closer to the rachis and is frequently, though not in Morris’s
specimen, overlapped by the upper edge of the next lower pinna. A
re-examination of the type-specimen in the British Museum confirms this
interpretation. The pinnae of _Ptilophyllum_ are characterised by their
attachment to the upper face of the rachis which they almost completely
cover; the upper angle is rounded and in a few cases auriculate
(fig. 592); the lower angle of the base is slightly rounded and not
infrequently hidden by the imbrication of the adjacent pinna; it is
occasionally auriculate (fig. 593). The pinnae are attached by nearly
the whole base, but the upper angle is free. The veins are parallel,
sub-parallel or, especially in the proximal portion of the lamina,
oblique. The pinnae are linear, varying considerably in relation of
length to breadth and in the form of the apex; they are straight or
more or less falcate. The epidermal cells of such _Ptilophyllum_
fronds as have been examined are characterised by strongly looped or
sinuous walls; the stomata, confined to the lower surface, are roughly
circular and the guard-cells are at right-angles to the veins and not
appreciably sunk. Fig. 594 represents the appearance of a stoma in
surface-view: ‘on either side of the central slit-like pore are two
elliptical or hemispherical structures; they are somewhat flattened
when they abut on the pore, and have rounded ends.... Between these
and the subsidiary cells lie two other thickened patches, more or
less hemispherical in shape, and apparently overlying the central
structures.’ On the analogy of similar appearances in recent Cycads Mr
Thomas[1462] interprets the two pairs of thickened patches as belonging
to the upper and lower sides of the highly inclined guard-cells. This
author calls special attention to the abundance on some of the fronds
included in the aggregate species _P. pecten_ of regular rows of
circular hair-scars preserved as small annulate projections, ·03–·04
mm. in diameter. A comparison of the cuticles of different forms of
_Ptilophyllum pecten_ enabled Thomas to recognise more than one type:
for one of these the name _Ptilophyllum hirsutum_ is proposed. It is
by such work as this that we may hope to discover differentiating
characters.
[Illustration: Fig. 590. _Ptilophyllum pecten_ (_P. cutchense_) and
_Williamsonia Blanfordi_. [Drawn from a specimen figured by Feistmantel
(76²) Pl. +xii.+ fig. 6.]]
[Illustration: Fig. 591. Part of the type-specimen of _Ptilophyllum
cutchense_ Morris. (British Museum; × 3.)]
[Illustration: Fig. 592. _Ptilophyllum pecten._ (Manchester Museum,
Williamson Coll. 3726.)]
[Illustration: Fig. 593. _Ptilophyllum pecten._ From the Lower
Estuarine beds, Cleveland, Yorkshire. (After Thomas; nat. size.)]
[Illustration: Fig. 594. _Ptilophyllum pecten_; stoma. (After Thomas
and Bancroft.)]
The different forms of _Williamsonia_ flowers found in association
with fronds of the _Ptilophyllum_ habit also point to the inclusion
of more than a single species under the group-species _P. pecten_. As
additional evidence is obtained further analysis will be possible,
but in dealing with impressions which include specimens transitional
from one form of frond to another, the most convenient and to my
mind the most logical course is to treat a species as an aggregate-
or group-species. Some authors believe that the two fronds described
by Phillips as _Cycadites pecten_ and _C. pectinoides_ are distinct
species[1463], but there would seem to be no adequate reason for this
view. The fronds described by Heer[1464] from the Lower Cretaceous of
Greenland as species of _Zamites_ and similar leaves from Graham Land
included in that genus by Halle[1465] are in my opinion inseparable
from _Ptilophyllum_, and this applies equally to _Otozamites Hislopi_
(Old.) (fig. 589) and _O. abbreviatus_ as figured by Feistmantel
and by Halle. The nomenclature of Cycadean fronds having the habit
of _Ptilophyllum pecten_ is a great difficulty: after carefully
reconsidering the whole question and comparing Feistmantel’s figured
specimens with the large series of English fronds the conclusion
reached is that the characters exhibited by ordinary impressions do not
admit of any satisfactory grouping under well-defined specific types.
In the first place, as already indicated, the use by some authors of
the generic names _Ptilophyllum_, _Otozamites_, and _Zamites_ creates
a false impression of the degree of difference between the numerous
forms of frond agreeing more or less closely with the specimens
on which were founded the species _Ptilophyllum acutifolium_, _P.
cutchense_, _P. pecten_, and _P. pectinoides_ (figs. 587, 591, 595,
etc.). In his important memoir on the Jurassic flora of Graham Land
Halle[1466] discusses the limitation of _Ptilophyllum_, _Zamites_,
and _Otozamites_. He employs _Zamites_ for fronds with linear pinnae
attached to the upper face of the rachis by a base which is more
or less, but often very little, rounded and always asymmetrical,
with or without a basal callosity: fronds of the type _Z. gigas_ he
includes in the section _Euzamites_, while _Z. borealis_ and similar
forms (fig. 597) are referred to a second section, _Subzamites_. It
is in the sense of Halle’s section _Euzamites_ that the generic name
_Zamites_ is employed in this chapter. On the other hand the fronds
grouped by Halle as _Subzamites_ have pinnae with the basal angles of
the lamina very slightly rounded precisely as in _Ptilophyllum_ as
seen in fig. 596 (_cf._ fig. 598 which represents fronds referred by
Halle to _Zamites_); and they are not distinguished by any feature of
generic importance from _Ptilophyllum_ as defined on page 519. The
species _Zamites pusillus_, _Z. Anderssoni_, and _Z. antarcticus_ (fig.
598) described by Halle from Graham Land as well as Heer’s Arctic
forms[1467] _Z. borealis_ (fig. 597), _Z. speciosus_, _Z. brevipennis_,
and others are transferred to _Ptilophyllum_ as types agreeing very
closely with _P. pecten_ and in some cases not clearly distinguishable
from it even specifically.
_Otozamites_ is the name employed by Halle for fronds with pinnae
having contracted, asymmetrical and auriculate, bases, the anterior
lobe being more developed than the posterior. The asymmetry of the
pinna-base is considered an essential feature. As Halle states it
is very difficult in some instances to draw a distinction between
_Otozamites_ and _Ptilophyllum_. As used in this chapter _Otozamites_
signifies fronds with pinnae characterised by an auriculate base, a
lamina usually broader than in _Ptilophyllum_, and by more spreading
veins (fig. 604). The not infrequent occurrence of auriculate pinnae on
fronds (fig. 603, A) which cannot be separated from typical examples of
_P. pecten_ illustrates the narrow dividing line as regards the form
of the pinna-base between _Ptilophyllum_ and _Otozamites_. The Indian
species _O. Hislopi_ (fig. 589) and _O. abbreviatus_, to which Halle
refers some Antarctic fronds, cannot be distinguished from the English
_P. pecten_ or Feistmantel’s and Morris’s Indian fronds described as
_P. cutchense_ and _P. acutifolium_: these forms are therefore included
in _Ptilophyllum_.
_Ptilophyllum_ (_Williamsonia_) _pecten_ (Phillips).
This designation is employed in a wide sense for a group of fronds
exhibiting a considerable range in size, in the relative breadth and
length of the linear pinnae, and in other features. Under _P. pecten_
are included (i) the English fronds from Yorkshire first described
by Phillips[1468] as _Cycadites pecten_ and _C. pectinoides_, the
former from the Middle shale, the latter from the Lower shale of the
Yorkshire coast, together with the Stonesfield slate specimens named
by Sternberg[1469] _Polypodiolites pectiniformis_ (fig. 595) and by
Brongniart[1470] and Lindley and Hutton[1471] _Zamia pectinata_; (ii)
the Indian specimens already considered and (iii) numerous examples
recorded under different names from Jurassic strata in many countries.
Fronds from the Yorkshire coast named by Brongniart[1472] _Zamia
Goldiei_, though regarded by some authors as examples of _Otozamites_,
are probably referable to _P. pecten_. Andrae’s _Pterophyllum
rigidum_[1473] (fig. 596) from Steierdorf is almost certainly a form
of _Ptilophyllum pecten_. The specimen shown in fig. 587 is one of the
few examples of fronds apparently preserved in their original position
attached in a cluster to a _Williamsonia_ (_Bucklandia_) type of stem.
The range in size and form of the pinnae is illustrated in figs. 588,
592, 593.
[Illustration: Fig. 595. _Ptilophyllum pecten._ The specimen figured
by Sternberg as _Polypodiolites pectiniformis_. (Oxford Museum; ⅚ nat.
size.)]
[Illustration: Fig. 596. _Ptilophyllum pecten._ Andrae’s
_Pterophyllum rigidum_ from Steierdorf, Banat. (British Museum, No.
41438; nat. size.)]
Fronds linear, tapering gradually towards the base and apex, often
characterised by a marked uniformity in breadth. The pinnae, short or
comparatively broad or long and narrow, are straight or more or less
falcate; the apex is obtuse or acute or the upper margin of the lamina
may be almost straight and the lower edge curved abruptly upwards
at the apex; the pinnae are usually attached obliquely to the rachis
but may be almost at right-angles; with the exception of the upper
angle, the whole of the base is attached to the frond-axis; the base
of the lamina may be symmetrical, both angles being slightly rounded,
or asymmetrical, the upper or less frequently the lower corner being
auriculate (figs. 592, 593). There is no basal callosity on the lamina
nor is there a median sinus. The veins are more or less spreading at
the base but for the most part parallel. The features of the epidermal
cells and stomata are mentioned in the general account of the genus.
Fertile shoots of plants with this type of frond are described
under _Williamsonia_. Very little is known of the stems which bore
_Ptilophyllum_ fronds, but as stated on page 488 Indian specimens show
leaves of _Ptilophyllum cutchense_ attached to a piece of stem (fig.
579) having the characters of _Bucklandia_ and characterised by a
xylem-cylinder denser than in recent Cycads; the structure of the wood
at least in the Indian stem is rather pycnoxylic than manoxylic.
The fronds grouped under _Ptilophyllum pecten_ are very widely
distributed in Jurassic floras; they are recorded from many
localities in Europe, from Turkestan[1474], India, Graham Land[1475],
Patagonia[1476], and elsewhere.
As thus defined this ‘species,’ or more correctly this group of forms,
undoubtedly includes more than one species in the strict sense, but
without additional data it is maintained that the recognition of
clearly defined specific types or varieties is beyond our power.
It may be urged that in view of the wide geographical range of the
_Ptilophyllum pecten_ type of frond and the admitted probability that
several species in the narrower sense are represented, distinctive
specific names should be retained even though under such designations
are included forms that, so far as can be seen from impressions,
exhibit no constant distinguishing features. My purpose is to emphasise
the futility of attempting to found well-marked species on the
available material. The student must decide for himself what course
to pursue, whether to retain such a specific name as _cutchense_ for
the Indian fronds or to employ that and other specific names as
designations of geographical types differing in no clearly defined
or constant characters from examples of the English _Ptilophyllum
pecten_. A comparative examination of the cuticular membranes in the
comparatively few cases where that is possible would probably furnish a
basis for a satisfactory subdivision of the group-species.
The names _Ptilophyllum Anderssoni_, _P. boreale_, and _P. antarcticum_
are retained for certain forms selected from a number of closely allied
types partly on the ground that these fronds exhibit some more or less
well-marked distinctive characters and in part as a recognition of the
existence of geographical forms.
_Ptilophyllum boreale_ (Heer).
Heer[1477] described numerous well-preserved impressions of pinnate
fronds from the Lower Cretaceous plant-beds of Kome, Greenland, which
he referred to several species of _Zamites_ though the differences
between them are hardly of specific rank. An inspection of several
of the figured specimens in the Stockholm Museum showed that Heer’s
drawings are in the main accurate. _Zamites borealis_ (fig. 597) is
characterised by small linear pinnae attached to the upper face of
the rachis, the stoutness of which is a noteworthy feature; the veins
are parallel and simple. In the shape of the pinnae, including the
base-characters, this species agrees closely with _P. pecten_. The
slightly falcate or straight pinnae are 1·7–2 mm. broad and reach
a length of 15 mm.; in _Z. speciosum_ Heer, probably specifically
identical with _P. boreale_, the pinnae are relatively longer, and in
_Z. brevipennis_ Heer they resemble the shorter pinnae of some of the
narrow fronds of _P. pecten_.
A preparation of the cuticle of a pinna of _P. boreale_ made by
Mr Thomas from a specimen in the Stockholm Museum shows a marked
difference between the upper and lower epidermis: the cells on the
upper surface of the lamina have very thick and sinuous walls precisely
as in _P. pecten_, but the cells are often broader than long and not
elongated parallel to the long axis of the pinna; those of the lower
epidermis are thinner and less clearly preserved: the stomata, which
appear to be like those of _P. pecten_, are scattered and not in rows.
[Illustration: Fig. 597. _Ptilophyllum boreale_ (Heer). Drawn from
one of the specimens from the Lower Cretaceous beds at Ekkorfat,
Greenland, figured by Heer. (Stockholm Museum; nat. size and a few
pinnae enlarged.)]
_Ptilophyllum antarcticum_ (Halle).
The fronds from the Jurassic rocks of Graham Land, described by Halle
as _Zamites antarcticus_[1478], are very similar to some forms of _P.
pecten_ and to _P. boreale_ and other Greenland forms; the linear
subacute pinnae are attached to the upper face of the rachis at a wide
angle and the base of the lamina is truncate and may be very slightly
constricted. The veins are dense, as many as 5 in 1 mm., and they are
occasionally forked near the base (fig. 598, A).
[Illustration: Fig. 598. A, A′, _Ptilophyllum antarcticum_. B, _P.
Anderssoni_. (After Halle.)]
_Ptilophyllum Anderssoni_ (Halle).
This Graham Land species (fig. 598, B), referred by Halle to
_Zamites_[1479], is of the same general type as _P. pecten_, but
is characterised by a coarser venation and by the wider angle of
attachment of the pinnae.
_Ptilophyllum Dunkerianum_ (Goeppert).
Goeppert[1480] proposed the name _Pterophyllum Dunkerianum_ for some
specimens from the Wealden of North Germany which were afterwards
figured by Dunker[1481]. Miquel[1482] included the species in his genus
_Dioonites_ and this name has been adopted by other authors. Attention
has been drawn to the inconsistent use of the title _Dioonites_[1483],
and I have previously employed the name in a sense similar to that in
which it has been adopted by Nathorst, that is for fronds with long
and narrow pinnae without any basal constriction and not auriculate,
attached more or less at right-angles to the upper face of the
rachis; but so defined _Dioonites_ differs in no essential particular
from forms of _Ptilophyllum_ or from fronds referred by authors
to Schimper’s genus _Ctenophyllum_. The name _Ctenophyllum_[1484]
was instituted for certain fronds differing in some points from
_Otozamites_ and _Dioonites_. One such type is _Ctenophyllum_
(_Ptilophyllum_) _pecten_ (Lind. and Hutt.): this is quoted in Zittel’s
_Handbuch_ as a typical representative of the genus. Schimper followed
Feistmantel in his definition of _Ptilophyllum_, a definition which
is not in accordance with the characters of the fronds on which it
was founded by Morris. Fontaine, on the other hand, has applied
_Ctenophyllum_ to fronds of a different type which are now included in
the genus _Pseudoctenis_. There would seem to be no adequate ground for
the retention of _Ctenophyllum_ as a generic designation.
The Wealden species _P. Dunkerianum_ is characterised by the following
features: rachis fairly stout, pinnae approximate, linear 2–3 mm. broad
and reaching a length of 11 cm. or more, gradually narrowed towards the
apex, attached in two almost contiguous rows to the upper face of the
frond-axis: the lower margin of the lamina may be slightly decurrent,
_e.g._ in the apical part of the frond or very slightly broadened and
bluntly rounded. The pinnae are attached at right-angles or, near the
apex, obliquely; veins 5–6, parallel. The epidermal cells as figured
by Schenk[1485] have very sinuous walls and are identical with those
of the English and Indian forms of the group-species _P. pecten_; the
stomata are confined to the lower surface. If Schenk’s drawings of the
stomata are correct they differ from those of other species of the
genus in their simpler structure; there are no subsidiary cells and
the guard-cells show no cuticularised bands. In habit this species
resembles _Encephalartos Ghellinckii_ Lehm. (fig. 382). The superficial
resemblance of the narrow linear pinnae to those of _Cycadites_ led
Dunker and Schenk to refer to that genus some specimens which have
since been described as identical with _P. Dunkerianum_.
=ZAMITES.= Brongniart.
In the first instance the generic name _Zamites_ was used in addition
to _Zamia_ for certain pinnate fronds including species[1486],
such as _Z. Bechei_, which are now regarded as typical examples of
_Otozamites_. Subsequently Brongniart gave up _Zamia_ for fossil fronds
and applied _Zamites_ to fronds with entire pinnae, not truncate at the
apex and not decurrent but slightly constricted at the base. Braun’s
two genera _Podozamites_ and _Pterozamites_ were relegated to the
position of subgenera. The name _Podozamites_ has been employed by
Schenk[1487] for specimens now included in _Zamites_, and _Zamites_ is
used by him[1488] for some fossils which are examples of _Podozamites_
as generally understood. Goeppert’s definition[1489] of _Zamites_
includes fronds with pinnae of the _Otozamites_ type, and this author
pertinently compares _Zamites_ with recent _Encephalartos_ leaves.
Pomel[1490] proposed the name _Crossozamia_ for certain fronds of the
_Zamites_ type, but this genus with several others instituted by the
same author has not been adopted. Bornemann[1491] described _Zamites_
as comprising species with a greater or less resemblance to the fronds
of recent Zamias.
As defined below, _Zamites_ fronds may be compared with those of
some species of _Encephalartos_, _Ceratozamia_, and _Macrozamia_.
There has been considerable difference of opinion with regard to
the range of form in the pinnae that it is advisable to include in
_Zamites_. The name _Zamiophyllum_ was proposed by Nathorst[1492]
for a Wealden species, described by Ettingshausen as _Pterophyllum
Buchianum_ (fig. 601, A–C), characterised by a decrease in the breadth
of the linear pinnae towards the point of attachment and, according
to Nathorst’s description, by the lateral attachment of the pinnae.
An examination of specimens of this type from English rocks[1493]
enabled me to show that the pinnae are attached to the upper face
of the rachis. Zeiller[1494] has also included _Zamiophyllum_ in
_Zamites_, but Halle’s recent definition[1495] of the latter genus
excludes fronds of the _Zamiophyllum_ type. Schimper instituted the
name _Glossozamites_[1496] for fronds bearing pinnae with rounded and
slightly contracted bases and borne on grooves on the upper surface
of the rachis (fig. 601, F). In venation the pinnae agree with those
of _Otozamites_ but the base is not auriculate. Kurr’s Liassic
species _Pterophyllum oblongifolium_[1497] included by Schimper in
_Glossozamites_ is probably an _Otozamites_. Another species referred
to this genus is Schenk’s _Podozamites Zitteli_[1498] from the Urgonian
of Austria (fig. 601, F): in this species the slightly falcate pinnae
with obtuse apices have rounded and not auriculate bases and there is
some evidence of a basal callosity. This species agrees so closely
with such a typical _Zamites_ as _Z. gigas_ that it is difficult to
see on what grounds the retention of _Glossozamites_ is desirable.
A Portuguese specimen referred by Saporta[1499] to _Glossozamites_,
_G. brevis_, is founded on a single specimen very like a leaflet of
_Otozamites Klipsteinii_ (Dunk.); and _G. parvifolia_ Yok.[1500] from
China has no claim to be included among Cycadean fronds. Feistmantel’s
_Glossozamites Stoliczkanus_[1501] is almost certainly a leaf of
_Cordaites_. For certain fronds originally described as _Zamites_
Zeiller[1502] has instituted the genus _Plagiozamites_. An important
question as to the type of frond which may conveniently be included
in the genus _Zamites_ was raised by the application of this name by
Heer to some Lower Cretaceous fronds from Greenland, _Z. borealis_ (=
_Ptilophyllum boreale_, fig. 597), and others which differ in the form
of the pinnae from species usually regarded as typical of the genus.
Halle[1503] accepts the Greenland species as examples of _Zamites_
though he distinguishes them by a sectional name _Sub-Zamites_; he
defines _Zamites_ as including fronds with pinnae attached to the
upper face of the rachis with a contracted and always symmetrical base
though in some cases the basal contraction is exceedingly small; there
is a more or less distinct basal callosity. He recognises two types,
(i) _Eu-Zamites_, _e.g._ _Zamites gigas_ (fig. 599), in which the
pinnae are strongly contracted basally and have a callosity, and (ii)
_Sub-Zamites_, _e.g._ _Z. borealis_[1504], etc., in which the pinnae
are not so broadly rounded at the base and retain the same breadth to
the point of insertion where they are ‘very rapidly and very little
contracted,’ with or without a basal callosity. The basal callosity
in these forms is not shown in many of the pinnae and is at most but
a slight rounding of the angles of the truncate base. The specimens
referred by Halle to _Sub-Zamites_ do not appear to differ in any
feature worthy of generic rank from _Ptilophyllum_.
In the following definition _Zamites_ is employed in a sense more or
less in accordance with Brongniart’s usage but with the inclusion of
such forms as _Z. Buchianus_, the type of Nathorst’s _Zamiophyllum_,
and the exclusion of Heer’s Arctic and Halle’s Antarctic fronds
referred by them to _Zamites_.
Fronds broadly lanceolate reaching a length of over 60 cm.; pinnae
more or less oblique or at right-angles to the rachis (fig. 599),
attached to the upper surface but not completely covering it, linear
or linear-lanceolate, acuminate or obtuse, usually abruptly contracted
at the rounded base and more rarely _(e.g._ _Z. Buchianus_, fig. 601)
gradually tapering to the proximal end, with or without a callosity
at the symmetrical base; veins divergent at the base, simple or
dichotomously branched, for the most part parallel to the edges of the
lamina and slightly divergent in the apical region. The presence of a
basal callosity, such as is best seen in the pinnae of recent species
of _Macrozamia_, is not a feature of great importance and cannot be
easily recognised in many impressions. In the process of fossilisation
the pinnae are often flattened against the surface of the rachis and
this may produce transverse wrinklings of the lamina suggestive of a
basal thickening. In some cases stems of the _Bucklandia_ type occur
in connexion with _Zamites_ fronds (fig. 541). An account of these
stems, and of inflorescences of _Williamsonia_ which were borne by
some at least of the plants with _Zamites_ leaves is given in Chapter
+xxviii.+ In such examples of _Zamites_ as have been examined the
epidermal cells have sinuous walls and the stomata[1505], confined to
the lower face of the lamina, occur in rows with their long axis at
right-angles to that of the pinnae.
_Zamites_ ranges from Rhaetic to Lower Cretaceous strata.
_Zamites truncatus_ Zeiller.
A Rhaetic species from Tonkin[1506] characterised by oval linear pinnae
given off at a wide angle, alternate and not contiguous; apex obtusely
truncate, gradually narrowed to a cuneate base which is rounded or
elliptical and has a more or less definite callosity. The pinnae vary
from 3 to 5 cm. in length and from 5 to 13 mm. in breadth.
_Zamites gigas_ (Lindley and Hutton).
The specific name _gigas_ is retained in preference to that of
_Mantelli_ employed by Brongniart[1507] on the ground that he
afterwards discarded it in favour of the designation proposed by
Lindley and Hutton[1508], and because their name has been generally
adopted.
Fronds large, exceeding 60 cm.; broadly linear lanceolate; the
comparatively slender rachis bears alternate linear lanceolate pinnae
with a rounded and usually slightly swollen base and an acuminate apex.
At the apex of the frond the pinnae are narrow and linear (fig. 599)
and almost parallel to the rachis; in the lower part they are shorter
and relatively broader and attached approximately at right-angles. The
numerous veins diverge from the centre of the base but for the most
part are parallel to the edge of the lamina. The form of the epidermal
cells and the structure of the stomata have recently been described by
Mr Thomas. The external features of the stem (fig. 541) are described
under the genus _Williamsonia_. In the case of fronds of this type
from English Jurassic rocks it would be legitimate to speak of them as
_Williamsonia gigas_, but in view of the fact that such fronds usually
occur as detached specimens and without any associated flowers it is
advisable, as Nathorst maintains, to retain the non-committal genus
_Zamites_.
[Illustration: Fig. 599. _Zamites gigas_. (British Museum, V.
2723_a_; ½ nat. size.)]
This type of frond is widely distributed in Jurassic strata. The
occurrence of many forms agreeing generally with the type-specimen
but differing from it in features that are not constant or of real
morphological importance renders accurate specific delimitation very
difficult. Species that appear to be indistinguishable from _Zamites
gigas_ by any well-marked characters are, _Zamites Feneonis_[1509]
Brongn., _Z. Moreaui_[1510] Brongn., _Z. Renevieri_[1511] Heer, and
_Z. claravallensis_[1512] Sap.; similarly _Z. Schmiedelii_ And.[1513]
is probably identical with _Z. gigas_. The Lower Cretaceous species
_Zamites bohemicus_[1514] Vel. and _Z. iburgensis_[1515] Hos. and von
d. Marck represent very similar forms.
_Zamites recta_ (Tate).
[Illustration: Fig. 600. _Zamites recta_. (Uitenhage series, S.
Africa.)]
This species was originally described by Tate[1516] as _Palaeozamia_
(_Otozamites_) _recta_ from Wealden strata in South Africa and
subsequently transferred to _Zamites_[1517]; it bears a very close
resemblance to _Z. gigas_. The fronds bear alternate linear pinnae
attached to the upper face of the rachis by a slightly contracted
and swollen base. The lamina has an acuminate asymmetrical apex and
the upper edge is slightly falcate; the larger pinnae are over 6
cm. long and nearly 1 cm. broad; the veins are frequently forked as
they converge towards the base of the lamina. No clear evidence of
association of these fronds in the Uitenhage series of South Africa
with _Williamsonia_ flowers has been discovered, but a specimen[1518]
in the Tate collection in the British Museum may be a badly preserved
cluster of bracts belonging to a _Williamsonia_. The rachis of this
species shows some peculiar features in the form of two rows of
alternate cushions in some partially decayed specimens. One of these is
shown in fig. 600; the cushions are raised oval projections with a flat
top, and pieces of the rachis without pinnae might easily be mistaken
for a Coniferous stem.
_Zamites Carruthersi_ Seward.
A species founded on specimens from the Wealden of Sussex[1519] and
recorded from Kimmeridge beds in Scotland[1520], characterised by
linear or linear-elliptical pinnae attached obliquely to the outer
part of the upper surface of the rachis, somewhat abruptly narrowed
at the proximal end but slightly broadened at the actual base (fig.
601, D, E). The pinnae appear to have been caducous and, as in fig.
601, D, the position of an absciss-layer is occasionally visible. In
habit the fronds bear a close resemblance to those of _Encephalartos
longifolius_ Lehm. The veins diverge from the base and are for the most
part parallel, though divergent at the bluntly rounded apex. If, as
may be the case, a specimen figured by Hugh Miller[1521] from Scotland
as _Zamites_ and subsequently named by Richards[1522] _Podozamites
Milleri_ is identical with _Z. Carruthersi_, the specific name
_Milleri_ has priority.
[Illustration: Fig. 601. A–C, _Zamites Buchianus_. D, E, _Zamites
Carruthersi_. F, _Zamites Zitteli_. (A–C after Seward; British Museum;
A, V. 2363; B, V. 2123_a_; C, V. 2227; F, after Schenk.)]
_Zamites Buchianus_ (Ettingshausen).
[Illustration: Fig. 602. _Zamites Buchianus_. (British Museum, V.
2120; ⅙ nat. size.)]
A Wealden and Lower Cretaceous species[1523] (figs. 601, A–C; 602)
represented in several European localities, also in North America
and Japan, reaching a length of over 70 cm.; in habit very similar
to _Ceratozamia mexicana, Macrozamia Macleayi_ and some other recent
Cycads. The rachis has a fairly broad median groove on the upper
surface; pinnae alternate, opposite or sub-opposite, from 3 to 20 cm.
long and from 1·5 to 2 cm. broad, linear, generally narrowed towards
the base, but in the more slender segments the reduction in breadth
is less obvious; attached obliquely to the rachis, slightly thickened
and broadened at the base (fig. 601, C), separated from the rachis
by a distinct absciss-layer and leaving an elliptical scar; usually
inclined at about 45° but the angle varies considerably in different
parts of a frond (fig. 602); apices generally tapering to a point, or
more or less obtusely rounded; veins numerous, parallel, and not as
a rule prominent. It is by no means unlikely that specimens figured
by Goeppert[1524] and some other authors as _Pterophyllum saxonicum_
or _Dioonites saxonicus_ are examples of this species. Fontaine[1525]
speaks of _Dioonites Buchianus_ as one of the most widely distributed
and characteristic members of the Potomac flora and it is described
from Japan by Yokoyama[1526] and Nathorst[1527]. This type appears to
be especially characteristic of Wealden strata.
=OTOZAMITES.= Braun.
Braun[1528] proposed the name _Otozamites_ for certain Mesozoic fronds
formerly included in _Zamites_, one of his types being _Otozamites
obtusus_ (Lind. and Hutt.) (fig. 603, B) originally regarded by
Brongniart as a Fern and named _Filicites Bucklandi_[1529]. The
auriculate form of the base of the pinnae and the spreading veins were
emphasised in the definition of the genus. As in the case of many other
Cycadean fronds the limits of the genus are not always easy to define,
but as described below the genus is on the whole fairly distinctive.
It is a very widely spread Jurassic type and extends from Triassic to
Lower Cretaceous rocks. The supposed Cretaceous species from Greenland,
_O. groenlandica_ Heer[1530], is probably not a plant-impression but a
polished groove in the rock.
Fronds pinnate, reaching a length of 50 cm. or more in some species;
pinnae alternate, separate or contiguous and imbricate, attached by
a portion of the base to the upper surface of the rachis, long and
narrow (fig. 603, A), broadly oval or almost orbicular, apex acute
or obtuse, base auriculate and asymmetrical[1531], the anterior lobe
being more prominent than the posterior edge of the lamina which is
usually rounded. The veins radiate from the base and pass obliquely
with occasional branching to the edge of the pinna; in the more
linear pinnae the veins may be parallel or nearly so. Zigno[1532]
figured a piece of an _Otozamites_ frond from Jurassic Italian strata
in connexion with a _Williamsonia_ and the actual specimen in the
Padua Museum amply justifies the impression produced by the published
drawing. Wieland’s investigations[1533] in Mexico have brought to light
many cases of association of _Otozamites_ fronds and _Williamsonia_
flowers.
[Illustration: Fig. 603. A, _Otozamites Goeppertianus_. B,
_Otozamites obtusus_ (= _O. Bechei_); type-specimen. (A, British
Museum, V. 2360; B, Oxford Museum.)]
The structure of the epidermis is partially described by Schenk[1534]
and more fully by Thomas[1535]: the epidermal cells have sinuous
walls and the stomata, apparently confined to the lower surface,
have guard-cells with hemispherical or spindle-shaped thickened
patches like those of some _Zamites_ fronds. In one species, _O.
Feistmanteli_ Zig., Thomas found about 100 stomata in 1 sq. mm. of
lamina forming almost contiguous lines between the veins. In the
account of the genus _Ptilophyllum_ reference is made to the occurrence
of pinnae with asymmetrical and auriculate bases, and it is only by
the comparison of a large number of specimens that a distinction can
be drawn between fronds that should be assigned to _Otozamites_ and
forms of _Ptilophyllum_ which exhibit a well-marked tendency towards
the _Otozamites_ type of pinna (_cf._ figs. 592, 593). The variation
in the form of the apices of pinnae and the relative position of the
pinnae in different parts of the same frond are features worthy of
notice in the determination of species[1536]. The different appearance
presented by an _Otozamites_ frond as viewed from the upper and lower
face is illustrated in fig. 604. There are no recent Cycads in which
the segments have auriculate bases, but in this feature as in the
sinuous epidermal walls _Otozamites_ agrees with some species of the
Fern _Aneimia_, _e.g._ _A. rotundifolia_ Schrad. (fig. 223, Vol. +ii.+
p. 288).
[Illustration: Fig. 604. _Otozamites Bechei._ A specimen in the Bristol
Museum seen from below (A) and above (B). M. S.]
_Otozamites Bechei_ Brongniart.
There is considerable confusion in the nomenclature of this species
described by Brongniart[1537] from Jurassic strata as _Filicites_
_Bechei_: in it Brongniart included a specimen from the Lias of
Axminster (Dorsetshire) previously figured by De la Beche as a fossil
Fern. It was on the Axminster specimen that Lindley and Hutton founded
the species _Otopteris obtusa_[1538], and as there is no doubt as to
the specific identity of their type-specimen (fig. 603, B) and De
la Beche’s fossil, Brongniart’s designation has prior claim[1539].
_Otozamites Bechei_ is, perhaps, best regarded as a comprehensive type
or a group-species in which numerous _Otozamites_ fronds described
by authors, on inadequate grounds, as distinct species may well be
included. Fronds agreeing generally with _O. Bechei_ were very widely
spread in Rhaetic and Jurassic floras.
Specimens from the Middle Jurassic rocks of Yorkshire have been
described as _Otozamites obtusus_ var. _ooliticus_[1540] to denote
a slight difference in the form of the pinnae from the Liassic
fronds from Dorsetshire; but the distinctive features of the variety
_ooliticus_ are unimportant and hardly worthy of consideration in a
general account of the species interpreted in a wide sense.
Fronds pinnate; pinnae usually more or less falcate, occasionally
straight and with parallel sides, attached obliquely to the upper side
of the rachis; imbricate or separate, the upper edge of the base of the
lamina strongly auriculate, the lower edge rounded; apex obtuse; veins
strongly divergent especially in the lobed base and extending obliquely
to the upper and lower edge of the lamina.
The specimen, from the Lias of Lyme Regis, drawn in outline in fig.
605, is an almost perfect frond: the pinnae are obtusely pointed,
slightly falcate, and there is a prominent lobe on the upper edge of
the base of the laminae.
The Jurassic species _Otozamites graphicus_[1541] (Leck. ex Bean
+MS.+), _O. vicetinus_ Zig.[1542], _O. Hennocquei_[1543] (Pom.),
_O. recurrens_ Sap., _O. Terquemi_[1544] Sap., _O. linearis_[1545]
Halle, are some of many examples of fronds agreeing closely with
_O. Bechei_, or in the case of _O. Terquemi_ with _O. graphicus_.
The fronds described by Halle from Graham Land as _O. linearis_
afford a good illustration of the range of variation in the pinnae: a
characteristic feature is the considerable length, exceeding 20 cm., of
the narrow linear fronds. The impressions from the Kome (Cretaceous)
beds of Greenland described by Heer as _Glossozamites Schenkii_[1546]
are probably closely allied to _O. Bechei_. The Rhaetic species _O.
Bucklandi_ Schenk[1547], _O. indosinensis_ Zeill.[1548], and _O.
Polakii_ Krass[1549], illustrate older examples of closely allied
types. Zeiller records _Otozamites_ pinnae similar to those of _O.
indosinensis_ from Rhaetic beds in Persia[1550].
_Otozamites Beani_ (Lindley and Hutton).
[Illustration: Fig. 605. _Otozamites Bechei._ (British Museum, 40672;
⅔ nat. size.)]
Founded on a specimen in the Scarborough Museum from the Middle
Jurassic of Yorkshire[1551] which is indistinguishable from Leckenby’s
type-specimen of _Otopteris mediana_[1552] in the Sedgwick Museum,
Cambridge. Long and narrow fronds exceeding 20 cm. in length,
characterised by the broadly oval, deltoid or sub-orbicular pinnae,
separate or partially imbricate and attached by a broad auriculate
base; apex bluntly rounded; veins numerous and spreading from the base
of the lamina. The pinnae, which may be 3·5 cm. long and nearly 2 cm.
broad, are narrower and longer in the distal part of the frond (fig.
606).
The Italian Jurassic species _Otozamites molianus_ Zig.[1553],
recorded also from Bornholm, is a very similar type. The generic name
_Cyclozamia_ suggested by Pomel for this form of frond has not been
adopted though it is applied by Schimper to _O. Bunburyanus_ Zig.
_Otozamites Bunburyanus_ Zigno.
A Jurassic species[1554] similar in the long and narrow form of the
frond to _O. Beani_ but distinguished by the much smaller segments
and by their more orbicular lamina (fig. 606, B). In habit the
fronds agree closely with the Fern _Nephrolepis Duffi_. Leckenby’s
species, _Otopteris tenuata_[1555], is probably the same as Zigno’s _O.
Bunburyanus_, the type-specimen of which in the Padua Museum consists
of a long and narrow frond with leaflets not exceeding 8 cm. in length;
the rachis is hidden by the imbricate auriculate bases of the leaflets.
Feistmantel[1556] refers to this species some pieces of very narrow
fronds with overlapping pinnae from Upper Gondwana beds in India. A
still smaller form is described by Möller[1557] from Bornholm as _O.
tenuissimus_, and _O. Bunburyanus_ is recorded from the same flora. _O.
Feistmanteli_ Zig.[1558] agrees in the form of the frond and in its
short and broad pinnae with _O. Bunburyanus_.
[Illustration: Fig. 606. A, _Otozamites Beani_. B, _Otozamites
Bunburyanus_.]
[Illustration: Fig. 607. _Otozamites bengalensis_. (Indian Geological
Survey, Calcutta; ⅔ nat. size.)]
_Otozamites bengalensis_ (Oldham and Morris).
This Indian species from the Rajmahal Hills[1559] and specimens of
the same type from the Cutch flora described as _O. contiguus_ Feist.
afford another illustration of long and narrow fronds with short and
relatively broad pinnae. The drawings published by Oldham and Morris
accurately represent the specimens: the longest frond is 21 cm. long
and neither end is complete (fig. 607); it is 9 mm. broad at the
narrower end and 1·5 cm. at the broader end. The rachis is represented
by a deep and broad groove; the actual bases of the leaflets are
not preserved, but their position shows that they were attached to
the upper face: this is clearly seen in the specimen described by
Feistmantel as _O. contiguus_ which shows also that the lamina is
auriculate at the upper edge of the base. The pinnae vary in shape;
the smaller ones are characterised by a strongly curved lower margin
and the upper edge is slightly curved or straight, while the larger
leaflets have more parallel edges and blunter rounded apices: the
latter form is well shown in the specimens unnecessarily distinguished
by Oldham and Morris as var. _obtusa_.
_Otozamites Klipsteinii_ (Dunker).
This Wealden species, first described by Dunker as _Cyclopteris
Klipsteinii_[1560], is remarkable for the large pinnae. The rachis is
fairly stout; the broadly oval or oblong pinnae vary considerably in
size and in the relation of breadth to length, in rare cases reaching
a length of over 8 cm. and a breadth of 2·4 cm.; apex obtuse, base
slightly auriculate and asymmetrical; veins numerous, radiating from
the point of attachment to the margin of the lamina. The occurrence
of finer lines between the more prominent veins may indicate the
presence of hypodermal stereome strands. Fig. 608 illustrates the
striking variation in the size of the pinnae on a single frond and
their attachment to the upper face of the rachis. In the breadth of
the segments _O. Klipsteinii_ resembles _O. Beani_ (Lind. and Hutt.),
_O. decorus_ Sap.[1561], _O. lagotis_ Brongn.[1562] and two species
from South Russia described by Thomas[1563] as _O. Izuimensis_ and
_O. giganteus_. The pinnae of _O. giganteus_ exceed 10 cm. in length
and 3 cm. in breadth, thus surpassing the largest segments of _O.
Klipsteinii_. Some pinnae from the Jurassic flora of Oregon made by
Fontaine the type of a new species, _O. oregonensis_[1564], may be
fragments of _O. Klipsteinii_. Nathorst[1565] records the occurrence in
Lower Cretaceous or Wealden beds in Spitzbergen of Cycadean leaflets
very like those of _O. Klipsteinii_.
_Otozamites Goeppertianus_ (Dunker).
This Wealden species, named by Dunker[1566] _Pterophyllum
Goeppertianum_, agrees in habit with some of those to which
reference is made under _O. Bechei, e.g. O. linearis_ Halle, and
represents a type of the genus with unusually narrow pinnae (fig.
603, A). The auriculate form of the lamina is feebly developed; the
linear-lanceolate pinnae are occasionally falcate and have acute
apices; as in many other species they were apparently deciduous. It is
by no means easy to distinguish some of these fronds from specimens
included in _Ptilophyllum pecten_.
[Illustration: Fig. 608. _Otozamites Kliptsteini_. (British Museum,
V. 3709; nat. size.)]
=DICTYOZAMITES.= Oldham.
This generic name was instituted[1567] for pinnate fronds from the
Rajmahal series of India, assigned by Feistmantel to a Lower Jurassic
horizon, but probably nearer in age to the Middle Jurassic series.
Morris, joint author with Oldham of the Memoir on the Rajmahal plants,
adopted the name _Dictyopteris_. _Dictyozamites_ agrees very closely
with _Otozamites_ but is readily distinguished by the anastomosing
veins (fig. 609), while the absence of a midrib differentiates it
from the Palaeozoic genus _Dictyopteris_. The genus is recorded also
from Jurassic strata in England, Bornholm, Japan[1568], Korea[1569],
and from a locality 60 nautical miles N.W. of Cape Horn in Tierra
del Fuego[1570]: the specimens from these localities differ only in
unimportant details from the Indian type. _Dictyozamites_ is confined
to Jurassic floras and appears to be especially characteristic
of Middle Jurassic floras. In India[1571] fronds occur in close
association with stems of the _Bucklandia_ type and, although there
is no proof of any connexion with stems or flowers, it is probable
that the fronds of this generic type were borne on stems similar to
those of _Bucklandia_ and that the flowers were constructed on the
_Williamsonia_ plan.
_Dictyozamites falcatus_ (Morris).
Morris[1572] described this Rajmahal species under the names
_Dictyopteris falcata_ and _D. falcata_ var. _obtusa_; the specimens
were included by Feistmantel under the designation _Dictyozamites
indicus_, the original term _falcata_ being discarded without adequate
reason. An examination of several of the figured fronds enables me
to confirm the accuracy of the published drawings and to extend the
description in a few particulars. Fronds pinnate of the habit of
_Otozamites_; pinnae comparatively thick, broadly linear, alternate,
varying considerably in size and in the form of the apex which may
be obtuse or acute. The pinnae are attached by the middle part of
the lamina only; the upper edge of the base is slightly rounded or
auriculate; the lower angle is generally more definitely lobed. The
imbricate bases completely cover the upper face of the comparatively
slender rachis. The longest pinna seen on an Indian frond is 6 cm. with
a breadth of 2 cm. Some of the pinnae on magnification exhibit a finely
tuberculate appearance, due no doubt to the presence of papillae on
the epidermal cells like those on the pinnae of English and Bornholm
specimens. This species is recorded by Yokoyama[1573] from Japan as
_D. falcatus_ var. _distans_, and a similar form, referred by him to a
distinct species, _D. grossinervis_, may be more appropriately named
_D. falcatus_ var. _grossinervis_[1574]. The Indian type occurs also in
Jurassic rocks of Korea, and Halle has discovered some _Dictyozamites_
leaves in Tierra del Fuego[1575] which he describes as _Dictyozamites_
sp. _cf._ _D. falcatus_: this record is of special interest from a
phytogeographical point of view.
_Dictyozamites Johnstrupi_ Nathorst.
This species[1576], from rocks usually spoken of as Liassic but not
improbably Middle Jurassic in age, differs from _D. falcatus_ in the
slightly more falcate form of the pinnae and in the more strongly
auriculate upper angle of the base of the lamina. The stomata[1577]
are confined to the lower epidermis and the strongly cuticularised
guard-cells frequently lie at right-angles to the course of the veins.
The epidermal cells have very sinuous walls (fig. 609, C) and in the
middle of each is a prominent papilla.
_Dictyozamites Hawelli_ Seward.
This Middle Jurassic type from Marske[1578], Yorkshire, differs from
_D. falcatus_ in the relatively broader segments, their straighter form
(fig. 609, B), and in the attachment to the rachis being slightly below
the middle of the pinna base. Fig. 609, A, shows the base of a pinna
and an oval scar similar to those on the rachis of some recent Cycads
(_cf._ fig. 387). The epidermis is like that in _D. Johnstrupi_ and as
in that species the stomata are confined to the lower surface. There
are approximately 120 stomata per square millimetre; each with two
subsidiary cells (fig. 609, C) of elongated form, and the guard-cells
have small thickened outgrowths or papillae as in _D. Johnstrupi_.
The epidermal features are described under _D. Johnstrupi_ and _D.
Hawelli_ (fig. 609, C): a fuller account of those in the latter species
will be found in the paper by Mr Thomas and Miss Bancroft.
[Illustration: Fig. 609. _Dictyozamites Hawelli._ (A, B, British
Museum; C, after Thomas and Bancroft.)]
=PTEROPHYLLUM.= Brongniart.
The name _Pterophyllum_ was first applied by Brongniart[1579] to some
fronds from the Lias of Höör, which he named _P. majus_ and _P. minus_,
species subsequently removed by Nathorst[1580] to Schimper’s genus
_Anomozamites_. Brongniart[1581] defined _Pterophyllum_ fronds, _e.g._
_P. Jaegeri_ (fig. 610), as pinnate, bearing pinnules of almost equal
breadth attached by the whole width of the base and with a truncate
apex; veins slender, equal, simple and slightly arched. There has been
considerable confusion and laxity in regard to the application of the
name _Pterophyllum_ and in many cases no clear distinction has been
recognised between this genus and _Nilssonia_. In _Nilssonia_ the
distinctive feature is the complete absence of any rachis uncovered
by the lamina on the upper face of well-preserved specimens, while
in _Pterophyllum_ the continuity of the lamina is broken by a greater
or less breadth of rachis in the middle line of the frond; the lamina
does not cover the rachis but is attached laterally, or at least the
two laminae of the frond, whether entire or deeply dissected, do not
meet in the middle of the rachis. A specimen from the Cretaceous of
Greenland described by Heer as _Pterophyllum concinnum_[1582] and now
in the Stockholm Museum is probably a piece of a _Nilssonia_; the
rachis is not exposed on the surface of the frond. In _Nilssonia_ the
veins are with few exceptions simple; in _Pterophyllum_ they are often
branched especially near their origin from the rachis: in _Nilssonia_
the segments are of unequal breadth; in _Pterophyllum_ they are
usually equal. It has been the practice of several authors to follow
Schimper[1583] in the employment of the generic name _Anomozamites_
for fronds with a more or less entire or irregularly pinnatisect
lamina which bear a very close resemblance to _Nilssonia_ except that
a portion of the rachis is exposed on the upper face. Potonié[1584]
used _Pterophyllum_ in a wider sense including both fronds with equal
pinnae and those of the _Anomozamites_ type: this more extended use
of _Pterophyllum_ is adopted by Zeiller[1585] who prefers to retain
_Anomozamites_ only as a sub-genus. It is in this sense that the
following definition is framed.
[Illustration: Fig. 610. _Pterophyllum Jaegeri._ From the Keuper of
Lunz; part of a frond 23·5 cm. long and incomplete. (British Museum, V.
1044; nat. size.)]
Fronds pinnate; pinnae linear, attached by the whole base, which may be
enlarged; the apex is truncate, rounded, or occasionally pointed; the
veins are simple or dichotomously branched and parallel to the edge of
the lamina. In some fronds (sub-genus _Anomozamites_) the segments are
unequal (fig. 615), short, broad and truncate, and the lamina may be
entire or divided into a few very unequal segments. The surface of the
rachis is never completely covered by the lamina on the upper face of
the frond and is often characterised by transverse wrinklings, possibly
due to the presence of ramental scales.
Some interesting xerophilous features have recently been described by
Halle[1586] in the lamina of _Pterophyllum (Anomozamites) marginatum_,
a Rhaetic species figured by Schenk and Nathorst from Franconia and
Scania. The pinnae were thick and succulent. Stomata are confined
to the lower surface and the edges of the upper face of the lamina
form a rounded curve causing the thick upper cuticle to abut on the
thinner stomatiferous lower cuticle, thus producing in impressions the
appearance of thickened margins.
There is no satisfactory evidence as to the nature of the reproductive
organs or stems of the plants which bore fronds of the type represented
by _P. Jaegeri_ (fig. 610) and other forms with equal segments. A
stem referred by Heer[1587] and by Leuthardt[1588] to _Pterophyllum_
was not found in connexion with leaves, and there is the same absence
of any convincing evidence in the case of the imperfect specimens
from the Keuper of Basel believed by Leuthardt to be male and female
inflorescences. On the other hand leaves of _Anomozamites_ are known
to have been borne on comparatively slender stems with dichasial
branching, and the reproductive shoots are of the same general type
as those known as _Bennettites_. This discovery is due to Nathorst
who founded the genus _Wielandiella_[1589] on fertile stems with
_Anomozamites_ fronds. Mr Thomas[1590] has recently obtained evidence
from Yorkshire Jurassic material pointing to a similar connexion
between _Anomozamites_ fronds and _Wielandiella_ stems. _Pterophyllum_
is further distinguished from _Nilssonia_ by the folded walls of the
epidermal cells and by the presence of two crescentic subsidiary
cells (fig. 611, A) instead of the ring of cells which surrounds the
guard-cells in _Nilssonia_ (fig. 611, B). Schenk[1591] figured a few
pieces of cuticle from fronds referred to _Pterophyllum_ in which
the walls are more or less sinuous, but the cells of _Pterophyllum
crassinerve_ Goepp.[1592] appear to have straight walls: this species
is, however, probably a _Nilssonia_. The stoma represented in fig.
611, A, is from the lower epidermis of _Pterophyllum_ (_Anomozamites_)
_Nilssoni_ (Phill.)[1593].
_Pterophyllum_ extends from Upper Carboniferous to Lower Cretaceous
strata and is especially characteristic of Keuper and Rhaetic floras.
A possible representative of the sub-genus _Anomozamites_ is described
by Ettingshausen from Tertiary beds in New South Wales as _Anomozamites
Muelleri_[1594].
[Illustration: Fig. 611. A, _Pterophyllum Nilssoni_; B, _Nilssonia
mediana_. (After Thomas and Bancroft.)]
_Pterophyllum Fayoli_ Renault and Zeiller.
This species[1595] was founded on a large frond from the Commentry
coalfield with a stout rachis bearing linear pinnae, attached along
a narrow groove on its outer edge, reaching a length of 12 cm. and a
breadth of 1 cm.; adjacent pinnae are united at the base. The apices
are pointed and there are 10–12 unbranched veins in the lamina. Fig.
612 shows a small piece of the large specimen in the Natural History
Museum, Paris.
_Pterophyllum_ sp. Arber.
The only representative of a Carboniferous frond of Cycadean habit
discovered in Britain is that recorded by Arber[1596] from Westphalian
strata at a depth of 1834 ft at Barfreston in Kent. A fairly stout
rachis bears incomplete pinnae the longest of which is slightly more
than 1 cm. in length and 1–1·5 cm. broad; each segment, very slightly
contracted at the base, has 3–4 occasionally forked veins. Arber
compares the fragments with _Pterophyllum blechnoides_ Sand. from
Germany[1597].
_Pterophyllum Cambryi_ Renault.
This Permian species from Autun[1598] is similar to _P. Fayoli_, but
differs in the more slender rachis and in the finer venation of the
linear, acute, pinnae. The pinnae in Renault’s specimen reach a length
of 4·8 cm. and are from 3·5–4 mm. broad; they are slightly confluent at
the base and the veins occasionally fork.
[Illustration: Fig. 612. _Pterophyllum Fayoli_. (From the
type-specimen, Paris; ⅓ nat. size.)]
Among other Palaeozoic species are _Pterophyllum Grand’Euryanum_ Sap.
and Mar.[1599] discovered by Grand’Eury in the Coal Measures of France,
_P. blechnoides_ Sand.[1600] from the Upper Coal Measures of Oppenau
and recorded by Geinitz[1601] from the Middle Permian of Germany, _P.
Cottaeanum_ Gutb.[1602], a similar type, also from Permian rocks,
but with coarser venation. The specimens figured by Geinitz as _P.
blechnoides_ and _P. Cottaeanum_ are in the Dresden Museum: the former
species is represented by a good impression on shale which shows the
generic characters very clearly.
_Pterophyllum Jaegeri_ Brongniart.
Brongniart[1603] founded this species (fig. 610) on material from the
Keuper of Stuttgart. The fronds are characterised by the relatively
narrow parallel-sided pinnae with rounded or truncate apices and little
or no basal contraction; the pinnae may be contiguous or separate.
There are 14–16 veins in each pinna. Leuthardt[1604], who figures
several examples of this species from Keuper strata at Basel, speaks
of the breadth-index of the pinnae as 12, a term employed to denote
the relation of the breadth to the length of a segment. _Pterophyllum
longifolium_[1605] is a very similar Keuper type: in this species
the pinnae are rather shorter and broader than in _P. Jaegeri_ and
contracted at the base; the apex is truncate or obtuse. The differences
between these species is, however, very trifling. The imperfectly
preserved fossils figured by Leuthardt[1606] as the inflorescences
of _Pterophyllum_ have not been found in connexion with fronds and
their nature is problematical. This and other species are recorded by
Krasser[1607] from the Lunz beds in Austria.
_Pterophyllum Bronni_ Schenk.
A Keuper species[1608] from Raibl in Carinthia distinguished by its
large pinnae, 15 cm. or more in length and 0·5 cm. broad, and by their
almost digitate disposition on the rachis. The fronds appear to be
relatively short: the upper pinnae are highly inclined while the lower
are given off at an obtuse angle; they are obcuneate or more or less
oblanceolate, with a truncate asymmetrical apex and rounded angles; the
base is slightly contracted. Arber[1609] has figured some specimens
from the Munich Museum in one of which there are five spreading pinnae
and a portion of the rachis; one pinna is undoubtedly attached and
the others, though probably in place, are not in actual connexion
with the axis. There is a close resemblance between this species
and _Sphenozamites Rogersianus_ Font.[1610]: in the American type
the fronds must have been 1 met. long; the leaflets, 19 × 9 cm., are
elliptical, broadest near the apex and attached by the middle of the
rounded base. Between the divergent and forked veins there is a fine
granulation probably due to the presence of papillae. _Pterophyllum
Bronni_ and _P. Rogersianum_ might be placed in Schimper’s genus
_Macropterygium_[1611], though another Raibl species, originally
described by Schenk as _Pterophyllum giganteum_[1612] and referred by
Schimper to _Macropterygium_, has much longer and relatively narrow
pinnae and agrees more closely with _Pterophyllum_ as the genus is
usually defined. In order to emphasise the distinctive features of
_Pterophyllum Bronni_ and Fontaine’s Virginian species they may
conveniently be spoken of as _Pterophyllum (Macropterygium) Bronni_ and
_Pterophyllum (Macropterygium) Rogersianum_.
[Illustration: Fig. 613. _Pterophyllum Braunianum._ (A, nat. size; B,
enlarged; after Schenk.)]
_Pterophyllum Braunianum_ Goeppert.
In this Rhaetic species[1613] (fig. 613) the narrow linear pinnae,
contiguous or more or less distant, are 1–2 mm. broad and may exceed 5
cm. in length though they are usually shorter; they are attached more
or less at right-angles to the sides of a transversely wrinkled rachis.
The base of the lamina is broadened and the veins are parallel, simple
or forked. The epidermal cells have sinuous walls.
_Pterophyllum Tietzei_ Schenk.
A Rhaetic species founded[1614] on specimens from Persia and described
also by Zeiller[1615] from Tonkin represented by fronds 1 met. long
and at least 15 cm. broad. The segments, 3–7 cm. long and 8–18 mm.
broad, are often set at right-angles to the rachis; the edges are
parallel but the lower edge bends upwards at the apex. The veins are
simple or forked and approximately 0·3 mm. apart.
_Pterophyllum Bavieri_ Zeiller.
This Rhaetic species from Tonkin[1616] and Persia[1617] is interesting
as affording an example of a frond with exceptionally narrow and
contiguous pinnae. The frond is narrow and lanceolate, 15–20 cm. long
with pinnae normal to the rachis, ·5–1 mm. broad and 7–25 mm. long
attached by the whole base which is sometimes slightly enlarged. The
veins are simple or forked, ·15–·25 mm. apart: the apices of the
segments are rounded or truncate and the form of the whole is similar
to that of _Pterophyllum aequale_ but narrower.
_Pterophyllum_ (_Anomozamites_) _inconstans_ Braun.
In habit this Rhaetic species[1618] resembles _Nilssonia compta_.
The linear-lanceolate fronds, as described by Zeiller[1619] in his
Tonkin memoir, attain a length of 20 cm. and a breadth of 4 cm. The
rachis, characterised by numerous transverse ridges, bears alternate
or sub-opposite leaflets often at right-angles; they are almost
rectangular and hardly longer than broad, attached by the whole of the
base, which may be broadened, to the upper face of the rachis, but
the lamina does not cover the whole of the rachis as in _Nilssonia_.
The pinnae vary in breadth on the same frond and occasionally the
lamina is continuous as in some forms of _Nilssonia_. Schenk[1620]
figures examples from the Rhaetic of Franconia in which the lamina
is very irregularly dissected and may be entire for a considerable
distance. The epidermal cells have slightly sinuous walls. A similar
type is represented by _Pterophyllum_ (_Anomozamites_) _Schenki_
Zeill.[1621], but the segments are contracted basally and become
wider towards the apex where, as in _P. inconstans_, the edges are
parallel. Feistmantel’s species _Platypterygium_ _Balli_[1622], though
superficially similar to _Pterophyllum_, appears to agree more closely
with _Pseudoctenis_.
[Illustration: Fig. 614. A, B, _Pterophyllum Nathorsti_; A from below;
B from above. C, _Nilssonia tenuicaulis_. (A, B, Gunn Collection,
British Museum; C, Arber Coll. Sedgwick Museum, 539; nat. size.)]
_Pterophyllum Nathorsti_ Seward.
This species, founded on a specimen in the Sedgwick Museum, Cambridge,
from the Middle Jurassic beds of Yorkshire, was formerly referred to
the genus _Dioonites_[1623], but since the Yorkshire specimens were
supplemented by material from Kimmeridge strata in Scotland[1624]
affording more definite information with regard to the attachment of
the pinnae it has been transferred to _Pterophyllum_. Pinnae laterally
attached to the rachis which in some specimens shows a transverse
wrinkling, narrow, linear, 3–4 mm. wide and reaching a length of 9 cm.
The base of the segments is slightly expanded; the apex is acuminate
or bluntly pointed: there are approximately three veins in 1 mm. of
lamina. This type (fig. 614, A, B) is similar to _Pterophyllum aequale_
Brongn. as figured by Zeiller[1625] from the Rhaetic of Tonkin and
agrees closely with some of the large Rhaetic specimens referred by
Schenk to _P. Braunianum_. The Jurassic fronds from Oregon described
by Fontaine[1626] as _Ctenophyllum angustifolium_ are similar forms
and a specimen from the Wealden of Germany included by Schenk in
_P. Dunkerianum_[1627] should probably be included in this species.
Other closely allied forms are represented by _P. distans_ Old. and
Morr.[1628] and _P. Footeanum_ from India.
[Illustration: Fig. 615. _Pterophyllum_ (_Anomozamites_) _Nilssoni_.
(British Museum, 39,306; nat. size.)]
[Illustration: Fig. 616. _Pterophyllum_ (_Anomozamites_)
_Lyellianum_. (Geological Survey Museum, 6396; nat. size.)]
_Pterophyllum_ (_Anomozamites_) _Nilssoni_ (Phillips).
The type-specimen, from the Jurassic beds on the Yorkshire coast
and now in the York Museum, was described by Phillips[1629] as
_Aspleniopteris Nilssoni_ and placed in _Pterophyllum_ by Lindley and
Hutton and many other authors[1630]. The fronds are linear; the lamina
may be almost entire or divided into unequal deep truncate segments;
the veins are simple or dichotomously branched (fig. 615). The leaves
are very similar to those of _Nilssonia_; they were probably borne
on stems similar to those described by Nathorst as _Wielandiella_.
Reference is made to the structure of the epidermal cells in the
account of the genus.
_Pterophyllum_ (_Anomozamites_) _Lyellianum_ (Dunker).
This Wealden species, originally referred by Dunker[1631] to
_Pterophyllum_, was afterwards transferred to _Anomozamites_[1632]. The
fronds, in habit resembling the larger Rhaetic species _P. Braunianum_
Goepp., are characterised by the narrow linear pinnae of almost equal
breadth attached approximately at right angles; there is a narrow line
of rachis separating the two rows of segments (fig. 616).
{=CYCADITES.= Sternberg.
{=PSEUDOCYCAS.= Nathorst.
The generic name _Cycadites_ was first used by Sternberg[1633] though
it has since been shown that the specimens for which he proposed it
belong to other genera. As employed by Brongniart[1634] and other
authors _Cycadites_ stands for fossil fronds agreeing in habit with
the pinnate leaves of recent species of _Cycas_ (fig. 387, A); the
presence of a single median in the linear pinnae is generally regarded
as an essential feature. _Cycadites_ may be defined as follows: Fronds
pinnate; pinnae alternate or opposite, linear entire, with a midrib
and no lateral veins, attached to the rachis by the entire base, the
lower margin of which may be slightly decurrent or narrowed near the
point of attachment. Epidermal cells with straight walls and stomata
agreeing in structure with those of the recent genus. As thus defined,
including the characters of the epidermal cells, the genus has no
representatives; but the generic name should also be applied, as
Miss Holden[1635] has recently suggested, to fronds of the _Cycas_
form which afford no information with regard to the structure of the
epidermis. The resemblance of _Cycadites_ fronds to those of _Cycas_,
coupled with the fact that impressions superficially resembling
megasporophylls of the recent genus are recorded from Mesozoic strata,
was considered sufficient justification for the employment of a name
implying close affinity to or even generic identity with _Cycas_. A
fuller knowledge of the epidermal characters of some of the fronds
hitherto included in _Cycadites_ has necessitated the substitution of a
new genus for _Cycadites_. An examination by Nathorst[1636] of Heer’s
Lower Cretaceous Greenland species _Cycadites Steenstrupi_ and of
other fronds showed that the epidermal cell-walls are sinuous and the
stomata arranged differently from those of _Cycas_. For these and other
reasons Nathorst proposed a new name _Pseudocycas_. He also pointed out
that the pinnae in the fossil fronds have as a rule a double ‘midrib.’
Nathorst’s discovery raised the question whether other fronds described
as _Cycadites_ should be transferred to _Pseudocycas_. Miss Holden’s
investigation of other supposed Mesozoic representatives of _Cycas_
leads to the conclusion that ‘it is not impossible that all Mesozoic
specimens of _Cycadites_ will turn out to be _Pseudocycas_.’ This
observer shows that _Cycadites Saportae_ Sew. and _C. Roemeri_ Schk.
agree in the sinuous walls of the epidermal cells with _Pseudocycas_;
and so far no species of _Cycadites_, in which it was possible to
examine the cuticular membrane, has been found that does not conform
to Nathorst’s definition of _Pseudocycas_ at least as regards the
structure of the epidermal cells. Nathorst defined _Pseudocycas_ in the
following sense: Fronds similar to those of _Cycadites_ and _Cycas_
but with pinnae characterised by a double ‘midrib,’ the stomata being
confined or almost confined to the groove between the two ‘midribs.’
Nathorst also notes that in _Pseudocycas_ the bases of the pinnae are
not contracted as is often the case in _Cycadites_ and _Cycas_, but
this is a feature of secondary importance. Miss Holden has, however,
expressed the opinion that the double ‘midrib’ is an untrustworthy
character and that the stomata are not always arranged as in the fronds
examined by Nathorst. Nathorst states that in _Pseudocycas Steenstrupi_
and _P. insignis_ the midrib though usually double may be single: the
same variation occurs in _P. Saportae_. Miss Holden found that an
impression made from a pinna of _Cycas siamensis_ showed a double line
on the upper face and a single rib on the lower; that is _Pseudocycas_
and _Cycas_ characters occur on a single pinna. On drying, the ridge on
the lower face of the lamina collapses and a groove is formed bounded
by two ridges.
In a recently published and interesting paper on ‘Some Xerophytic
Leaf-structures in Mesozoic Plants,’ Dr Halle[1637] makes some
important additions to our knowledge of _Pseudocycas_. He agrees
with Miss Holden’s views with regard to the use of the generic names
_Pseudocycas_ and _Cycadites_, but dissents from her interpretation
of the median groove as the result of shrinkage of a midrib. Part
of the evidence presented by Halle is based on the structure of the
leaf-cuticle as shown in microtome sections[1638]. He found that a
distinct median groove is always present on the pinnae of _Pseudocycas
insignis_ and other species. If the groove were due to collapse of
the tissue of a true median rib the presence of stomata—which in _P.
insignis_ are confined to the middle line of the lamina—below the vein
would be an unusual feature. He found no indication of a median vein
or of any vascular tissue. All that is revealed by an examination
of the cuticle is that the lamina has a well-defined groove bounded
by prominent ridges, and in _Pseudocycas Roemeri_ the groove is
deeper and is formed by the bending-back of the lamina. The stomata
are practically confined to the groove and in _P. insignis_ and _P.
Steenstrupi_ an additional protection against excessive transpiration
was afforded by elongated papillae.
In the sinuous walls of the epidermal cells and in the structure of the
stomata _Pseudocycas_ agrees with the Bennettitalean type as defined
by Thomas and Bancroft[1639]. The ‘midrib’ of the pinnae marks the
position of a pronounced groove and we have no information with regard
to the venation. As Halle says, protection against drought is afforded
by ‘other means than those usual among existing Cycads,’ which provide
against excessive transpiration by the sinking of the individual
stomata below the surface. The epidermal features of _Pseudocycas_
afford a striking example of the danger of basing conclusions on mere
impressions and they further emphasise the great difference between
Mesozoic Cycadean fronds and those of recent genera.
We have no knowledge of the nature of the reproductive organs of the
plants which bore _Pseudocycas_ fronds, but the agreement of the
stomata and epidermal cells with those in some Bennettitalean types
favours the inclusion of the genus in that class. It has previously
been pointed out that the impression figured by Heer[1640] in close
association with the Greenland specimens of _Pseudocycas Steenstrupi_
as a carpellary leaf of the _Cycas_ type is much too imperfect to
be identified and has no claim, as an examination of the actual
specimen in the Copenhagen Museum convinced me, to be compared with a
megasporophyll of _Cycas_. This view is shared by Nathorst.
In some cases the name _Cycadites_ has been applied to fragments
that might equally well belong to Conifers or other plants, and not
infrequently a careful examination of fossils referred to _Cycadites_
shows that the pinnae afford no evidence of a true midrib. Casts
of revolute pinnae like those of the recent species _Encephalartos
Ghellinckii_ (fig. 382) would present an appearance closely resembling
a strong midrib. Heer’s Siberian Jurassic species _Cycadites
sibiricus_[1641] is probably a piece of a _Taeniopteris_ or _Nilssonia_
frond, and _C. gramineus_ Heer[1642] should be referred to _Taxites_.
An examination of the Indian fronds described by Oldham and Morris and
Feistmantel as species of _Cycadites_ leads me to discard all of them
as trustworthy records of the genus: in _Cycadites confertus_[1643]
and _C. Blandfordianus_[1644] there appear to be several veins in
the pinnae and not a single midrib. _Cycadites constrictus_[1645]
is almost certainly a Conifer as Nathorst has also suggested. No
satisfactory example of _Cycadites_ has been described from Palaeozoic
strata; Goeppert’s _Cycadites gyrosus_[1646] is founded on material
too imperfect to determine, and an examination of his Culm species _C.
taxodinus_ in the Breslau Museum led me to refer it to a Conifer. The
specimens figured[1647] by Zeiller from Lower Gondwana rocks in India
as _Cycadites_? sp. are portions of linear leaves or leaflets 5 mm.
broad with a median rib but they can hardly be accepted as evidence of
the presence of a Cycadean plant.
[Illustration: Fig. 617. _Pseudocycas insignis._ From the Lias of
Höör. A, ⅚ nat. size; B, _ca._ × 2. (After Nathorst.)]
_Pseudocycas insignis_ Nathorst.
The fronds of this Cenomanian species from the West of Greenland reach
a breadth of 16 cm.; the rachis, 1 cm. broad, has two parallel ridges
on the upper surface and to these are attached at a wide angle the
broad bases of narrow linear pinnae reaching a length of 9 cm. and a
breadth of 2–3 mm. (fig. 617). The pinnae are thick and separate and
each has a double ‘midrib’ consisting of two parallel lines (fig.
617, B) which are occasionally replaced by one. The so-called double
‘midrib’ represents the two prominent ridges bordering the groove. The
stomata, confined to the median groove, are approximately circular and
the short epidermal cells have sinuous walls[1648].
_Pseudocycas Steenstrupi_ (Heer).
Nathorst refers this species, described by Heer as _Cycadites_, from
the Cenomanian of Greenland, to _Pseudocycas_ on the ground that the
epidermal cells are like those of _P. Steenstrupi_ and the stomata
are confined to a median groove. Heer figures an impression in close
association with the frond of this species which he identifies, without
any adequate reason, as a carpellary leaf like that of a _Cycas_.
_Pseudocycas Saportae_ (Seward).
It has recently been shown by Miss Holden that this Wealden English
species[1649] has the epidermal characters of _Pseudocycas_. In
external form it agrees closely with _Cycadites tenuisectus_ Sap.[1650]
from Lower Cretaceous rocks in Portugal, but nothing is known of
the epidermal features of the latter type. The rachis is broad and
flattened and bears alternate or sub-opposite pinnae of uniform breadth
attached at right-angles or obliquely to its upper surface (fig. 618).
The pinnae are 6–7 cm. long and about 1 mm. broad; their bases are
slightly expanded and the apices sharply pointed. Miss Holden[1651]
finds that the median rib is sometimes double and that the middle
region of the lamina is covered with stomata; the epidermal cells have
sinuous walls and stomata occasionally occur on each side of the main
median stomatal area. Dr. Halle[1652] of Stockholm, who has examined
cuticular preparations made from English specimens, confirms Miss
Holden’s observations as regards the stomata, but he shows that there
is no evidence of the existence of a midrib in the strict sense, the
appearance of a single or double median vein being due to the presence
of a dorsal stomatiferous groove, the edges of which would produce an
impression on the matrix of a double vein or, if the groove became
narrower, the impression would suggest a single midrib.
[Illustration: Fig. 618. _Pseudocycas Saportae._ From the Wealden,
near Hastings. (British Museum, V. 2777; ⅕ nat. size.)]
_Pseudocycas Roemeri_ (Schenk).
This Wealden species recorded from North Germany[1653] and the Sussex
coast[1654] has broader pinnae laterally attached to the rachis. Miss
Holden describes the stomata as covering the whole lower surface of the
pinnae except over the midrib. This description must be revised in the
light of Halle’s results obtained from an examination of the cuticle of
the type-specimen of the species in the Berlin Museum. He finds that
the edges of the pinnae are strongly revolute and thus form a deep
dorsal canal which is almost closed[1655], a form of lamina, as seen in
section, very similar to that of an _Empetrum_ leaf. The stomata are
confined to the groove. It may be that the specimen examined by Miss
Holden is specifically distinct or, as Halle also suggests, the cuticle
obtained from the English fossil may not represent the whole surface
but only the walls of the canal with possibly a portion of the cuticle
of the outer dorsal surface. This type of leaf described by Halle
is similar to that of _P. insignis_ with the xerophilous character
intensified.
_Cycadites Saladini_ Zeiller.
This species was founded by Zeiller[1656] on fronds from the Rhaetic of
Tonkin reaching a length of 40 cm. and 2–8·5 cm. broad with a rachis
3–4 mm. wide bearing contiguous linear pinnae 1·5–4·5 cm. long and
1·5–3 mm. broad with a more or less contracted base and a rounded or
obtusely pointed apex. The pinnae are attached almost at right-angles
or at an angle of 60°–80°. There is a clearly defined midrib.
It is not improbable that were the structure of the epidermal
cells known this species would be found to be another example of
_Pseudocycas_.
_Cycadites rectangularis_ Brauns.
This species[1657], first recorded from Rhaetic strata in Germany,
differs in the narrower and more acutely pointed pinnae from _C.
Saladini_. Miss Holden describes the midrib as double, but until
specimens are found which admit of an examination of the cuticles it is
impossible to decide whether it should be transferred to _Pseudocycas_.
The species is widely distributed in Rhaetic and Jurassic strata and
specimens are recorded from the Lias of Lyme Regis on the south coast
of England.
_Cycadites Renaulti_ Lignier.
This species, from the Middle Lias of Normandy[1658], is founded
on fronds 2·2–2·6 cm. broad with a rachis 3 mm. in breadth bearing
laterally-inserted pinnae almost at right-angles 11–12 mm. long and
1·25–1·50 mm. broad; it is very similar to _C. rectangularis_ which
occurs in the same beds.
II. +Nilssoniales.+
=NILSSONIA.= Brongniart.
This genus[1659] was named after the Swedish naturalist Nilsson who
had figured certain plants from the Lias of Höör referred by Fries to
the Ferns: these were named by Brongniart _Nilssonia brevis_ and _N.
elongata_ and classed with the Cycads. The type-specimens of the latter
species are regarded by Nathorst as a form of _N. brevis_. The history
of the genus is fully discussed in Nathorst’s able monograph[1660].
_Nilssonia_, founded on fronds which with one exception are known only
as casts or impressions, may be thus defined: Fronds with circinate
vernation, at least in the type-species _Nilssonia brevis_ (fig. 619,
C, D), similar in shape to the leaves of _Scolopendrium vulgare_ and
_Polypodium irioides_ and to such unusual forms of _Cycas_ fronds as
those reproduced in figs. 384, 387, I[1661], in which the laminae of
the pinnae are concrescent and form a continuous or deeply cut lamina.
They may reach a length of 60 cm. and a breadth of 10 cm. and some
specimens are known in which the leaf is less than 1 cm. in width. The
lamina is occasionally entire, but in the great majority of cases it
is more or less deeply cut into segments of unequal breadth varying
considerably in size and shape even in the same species, usually deep
and truncate and sometimes long and narrow (_e.g. N. pterophylloides_,
fig. 619, B). An important distinguishing feature is the attachment
of the lamina to the upper face of the rachis which it covers: the
extension of the lamina over the surface of the frond axis and the
rare occurrence of branching of the veins are characters in which
_Nilssonia_ differs from _Taeniopteris_. The veins are given off at
right-angles or obliquely from a very narrow groove occupying the
median line of the rachis; they are nearly always simple and in some
of the more fleshy leaves, _e.g. N. brevis_, they are seldom visible.
The surface of the lamina may be smooth or transversely corrugated. The
rachis forms a prominent rib on the under surface of the frond (fig.
620, A) and may be continued beyond the lamina as a short petiole.
Epidermal cells polygonal or rectangular, with straight walls in
contrast to the sinuous walls of _Taeniopteris_; some of the cells bear
strongly cuticularised papillae, possibly the bases of hairs (compare
the hairs on the fronds of _Acrostichum crinitum_, a Fern with leaves
similar in shape to some of the large entire fronds of _N. orientalis_
though relatively broader and with anastomosing veins). Stomata usually
confined to the lower epidermis and not very numerous; guard-cells
of rounded contour and without any special thickening surrounded by
6–8 accessory cells with thickened walls (fig. 611, B) forming a
chimney slightly raised over the stomatal pore[1662]. In _Nilssonia_
the guard-cells do not exhibit that regularity of orientation which
characterises the stomata of _Ptilophyllum_, _Otozamites_, and other
Bennettitalean fronds. Little is known of the anatomy of the leaves: in
a petrified leaf of _N. orientalis_[1663] from Upper Cretaceous rocks
in Japan there is no palisade-tissue and small groups of sclerenchyma
occur above and below the veins. The xylem appears to be centripetal,
but the preservation is far from satisfactory. A few secretory canals
were found near the edge of the leaf. We have no certain knowledge of
the reproductive organs. The small circular projections figured by
Schenk[1664] on some leaves of _Nilssonia polymorpha_ as sporangia
have no claim to be so regarded. In the description of _N. brevis_
reference is made to some seeds discovered by Nathorst which may belong
to that species. Nathorst suggests the possibility that the Rhaetic
fossil _Stenorrachis scanicus_ Nath. may be the seed-bearing shoot of a
_Nilssonia_, either _N. brevis_ or _N. polymorpha_, and if this surmise
is correct it almost necessarily involves the genus _Beania_[1665]
which has been tentatively referred to the Ginkgoales though without
any convincing evidence to support such connexion. Nothing is known of
the stems: the occasional occurrence of leaves converging towards a
common support points to a Cycadean habit. It is possible, as Nathorst
suggests, that the Rhaetic species _Bucklandia Saportana_[1666] may be
the stem of a _Nilssonia_.
[Illustration: Fig. 619. A, seed (_Nilssonia_?); B, _Nilssonia
pterophylloides_; C, D, _Nilssonia brevis_; E, _N. polymorpha_. (A–D ⅚
nat. size; E, slightly enlarged; after Nathorst.)]
_Nilssonia_ is especially characteristic of Jurassic and Rhaetic
floras; it occurs also in Triassic beds and extends into Cretaceous
floras.
Nathorst instituted the genus _Nilssoniopteris_[1667] for some
specimens from the Yorkshire coast which he believed to be examples of
_Nilssonia tenuinervis_ on the ground that the veins are dichotomously
branched and the epidermal cells have sinuous walls. Mr Hamshaw
Thomas[1668] has, however, shown by an examination of the specimens in
the Stockholm Museum that they belong to _Taeniopteris vittata_, and
Prof. Nathorst agrees with this conclusion. The name _Nilssoniopteris_
must therefore be abandoned. Miquel[1669] proposed the name _Hisingera_
for some _Nilssonia_ fronds, but it has not been adopted.
_Nilssonia polymorpha_ Schenk.
Linear fronds varying considerably in breadth and in the degree
of dissection of the lamina, which may be entire; the margin may
show broad and shallow crenulations or there may be a few narrow
and deep sinuses cutting the otherwise entire lamina into long and
narrow segments. More usually the lamina is divided to the rachis
into numerous truncate segments traversed by parallel, simple, veins
extending from a narrow groove in the middle of the rachis on the
upper surface of the frond (fig. 619, E). The veins run in very narrow
grooves in the generally flat but occasionally corrugated lamina[1670].
This species agrees very closely in habit with _N. compta_ and _N.
brevis_ and, as Nathorst points out, it is in some cases almost
impossible to distinguish _Nilssonia polymorpha_ from _N. brevis_.
Some of the fronds from the Rhaetic of Franconia described by Schenk
as _N. polymorpha_ are examples of _N. brevis_. In _N. polymorpha_ the
distal ends of the segments are blunter, the lamina is much less folded
and when folds or corrugations occur they are less regular than in _N.
brevis_. The epidermal cells are polygonal and have thick, straight,
walls: oval or circular papillae occur both on the lamina and rachis.
The stomata, confined to the lower surface, are between the veins and
each is accompanied by a ring of subsidiary cells (_cf._ fig. 611, B).
_N. polymorpha_ is a member of Rhaetic floras and is recorded also from
Liassic rocks at Höör[1671].
[Illustration: Fig. 620. A, B, _Nilssonia brevis_; A, section of
the frond; B, section of the lamina parallel to the rachis. C, _N.
saighensis_. (A, B, after Nathorst.)]
_Nilssonia brevis_ Brongniart.
This species[1672] (fig. 619, C, D), one of those from Höör on
which the genus was founded, has been very fully investigated by
Nathorst[1673] whose researches have cleared up many obscure features.
The young fronds are circinate like those of Ferns and _Cycas_. The
linear fronds agree generally in habit with those of _N. polymorpha_
and _N. compta_, but the lamina is thicker and is characterised by
regular transverse corrugations; the veins are very rarely visible
except in young leaves which have not reached their full thickness.
The fronds may be 50 cm. long and vary in breadth from 1·5 to 12 cm.;
the petiole is very short or the frond may be sessile. Between the
regular grooves on the upper surface the lamina is more or less convex;
seen from below the grooves are represented by ridges and between each
pair of ridges there are parallel folds, sometimes three (fig. 620,
B) or as many as six; and where the segments are narrow, that is the
strips of lamina between two grooves (or ridges), there may be only
a single fold which gives the appearance of linear segments with a
single midrib as in _Cycadites_, a misleading resemblance of special
interest in reference to the _Nilssonia_ fronds described by Oldham and
Morris[1674] and by Feistmantel[1675] as _Cycadites rajmahalensis_.
Owing to the fleshy nature of the leaf the difference between the
upper and lower side is particularly well marked in this species. The
lamina may be more or less entire, but is usually divided by deep
sinuses extending to the rachis into truncate or distally tapered
segments varying in breadth (fig. 619, C, D), the narrow segments being
characterised by a more pointed apex than in _N. polymorpha_. The
structure of the stomata and epidermal cells is of the type described
in the definition of the genus. Strongly cuticularised papillae,
incorrectly described by Schenk[1676] in _N. polymorpha_ as stomata,
occur on some of the epidermal cells: these may be the bases of hairs.
In some preparations Nathorst found patches of a resinous substance,
an interesting discovery in view of the occurrence of secretory canals
in the petrified leaf of _Nilssonia orientalis_ described by Dr
Stopes[1677].
[Illustration: Fig. 621. _Nilssonia rajmahalensis_ (= _Cycadites
rajmahalensis_). (Indian Geological Survey, Calcutta; nat. size.)]
_Nilssonia brevis_ occurs in Upper Rhaetic and Lower Liassic strata.
_Nilssonia pterophylloides_ Nathorst.
A Rhaetic Scanian species originally referred by Nathorst[1678] to
_Nilssonia_ but later removed by him to _Dioonites_[1679] and in
1909 reinstated in _Nilssonia_[1680] on the ground that the lamina
covers the upper face of the rachis. The segments are fairly uniform
in breadth and linear; they reach 10 cm. in length and are usually
5–7 mm. broad; the lamina is slightly tapered towards the apex (fig.
619, B). There are 3–10 parallel grooves on the upper face of the
segments and between each pair is a single unbranched vein. In close
association with portions of three fronds of this species Nathorst
found several oval bodies, 1 cm. × 7 mm., which he at first regarded
as ‘antherangia’ comparable with the sporocarps of the Hydropterideae,
but an examination of the carbonised tissue demonstrated that the small
rounded bodies contained in each of the ‘antherangia,’ originally
believed to be pollen-sacs, are grains of resin internal to a cuticle
of thick-walled cells and probably formed by secretory sacs in a fleshy
tissue. Internal to the resin-bodies is a second cuticle which may be
the remains of a nucellus, the outer cuticle and the resin belonging
to the sarcotesta. Nathorst’s careful examination of these fossils
shows that they are seeds (fig. 619, A) and were probably borne on
plants of _N. pterophylloides_, though an accidental association is not
improbable.
_Nilssonia compta_ (Phillips).
Broadly linear fronds varying considerably in size and in the breadth
and number of the truncate segments. In some cases the fronds exceeded
40 cm. in length and had a breadth of 9 cm. (fig. 622). The veins are
simple, parallel, and fairly prominent and the lamina shows clearly
the attachment to the upper surface of the rachis which is covered
by it as in all species of the genus[1681]. The structure of the
epidermis and stomata has recently been described by Thomas[1682].
Brongniart mentioned in the _Prodrome_ a species from the Lower Oolite
of Yorkshire under the name _Pterophyllum Williamsonis_[1683], but in
a later work this is given as a synonym of _N. compta_. _Nilssonia
compta_ bears a close resemblance in habit to _N. polymorpha_; it
agrees also with the large fronds described from the Upper Gondwana
of India as _Pterophyllum princeps_[1684]. Since attention was first
called to this similarity an examination of several of the figured
specimens has convinced me that the Indian fronds are either identical
with or at least closely allied to the European leaves. The apparent
lateral attachment of the lamina in the drawings published by Oldham
and Morris and Feistmantel is due to imperfect preservation; the
lamina ends in two raised ridges, and the discovery of a specimen
in which the lamina completely covers the rachis confirmed the
impression made by the other specimens. The Amurland Jurassic species
_Nilssonia Schmidtii_[1685] Heer though probably not identical with
_N. compta_ is a very similar type; it was originally described by
Heer as _Anomozamites Schmidtii_ and transferred by Nathorst[1686] to
_Nilssonia_: the veins are occasionally forked near the rachis and are
rather farther apart (·5 mm.) than in _N. compta_ and the segments are
broader and deeper than in the English species. _Nilssonia nipponensis_
Yok.[1687] a Jurassic species recorded from Japan and North America is
another similar type.
[Illustration: Fig. 622. _Nilssonia compta._ (Whitby Museum; nat.
size.)]
_Nilssonia orientalis_ Heer.
In this Jurassic and Lower Cretaceous species, founded on material from
Jurassic rocks in Siberia[1688], the lamina is generally entire. The
fronds exhibit a wide range in size and shape; they may have the form
of very narrow linear leaves barely 1 cm. across or may reach a breadth
of nearly 10 cm. The leaves from Middle Jurassic British strata named
by Nathorst _N. tenuinervis_[1689] are probably identical with Heer’s
type, and _N. Johnstrupi_[1690] Heer from the Lower Cretaceous of
Greenland may also be referred to _N. orientalis_.
The veins are at right-angles or oblique to the rachis and are very
numerous, three or more in a breadth of 1 mm.[1691] A species recently
described by Halle[1692] from Graham Land as _N. taeniopteroides_
agrees closely in habit with _N. orientalis_: in the southern form
the frond may have a length of 40–50 cm. and a breadth of 3 cm. The
entire lamina of _N. taeniopteroides_ tapers gradually towards the
base and is more rapidly narrowed in the distal region; the petiole is
at least 6–7 cm. long: the simple or branched veins, 15–20 in 1 cm.,
are given off from the axis at a wide angle. The more crowded veins in
_N. orientalis_ constitute one of the few features in which it differs
from Halle’s species, but the fact that the degree of closeness of the
veins is inconstant within the same species renders this distinction of
doubtful value. Halle compares his species also with _N. densinervis_
(Font.) originally described as _Platypterigium densinerve_ from
the Potomac beds[1693] and afterwards transferred by Berry[1694] to
_Nilssonia_ and considered by him to be identical with Fontaine’s
_Platypterigium Rogersianum_. An examination of some of Fontaine’s
specimens in the Washington Museum led me to refer the fronds to
_Nilssonia_[1695].
It is impossible to speak with confidence as to the absolute
specific identity of _N. orientalis_ Heer, _N. Johnstrupi_ Heer,
_N. taeniopteroides_ Halle, and some similar forms; but it is clear
that the linear fronds of this type characterised by an entire or
occasionally pinnatisect lamina were widely distributed in Jurassic
and Lower Cretaceous strata and persisted to the Upper Cretaceous
series in Japan. This form of frond is recorded from England, Scotland,
North America, Greenland, Spitzbergen[1696], Siberia, Russia,
Afghanistan[1697], Japan[1698], Graham Land, and elsewhere. Reference
has already been made to a petrified specimen of _N. orientalis_
described by Dr Stopes from Japan[1699].
Specimens described by Salfeld[1700] from the Corallian of Germany as
_Taeniopteris_ sp. may be _N. orientalis_; Bartholin’s _N. polymorpha_
from Bornholm, Velenovský’s Lower Cretaceous _N. bohemica_ and
Yokoyama’s _N. ozvana_ from Japan are other examples of fronds which
may be identical with _N. orientalis_[1701].
_Nilssonia tenuicaulis_ (Phillips).
This Jurassic species, while agreeing generally in habit with _N.
compta_, is characterised by the narrow and numerous linear segments
with a more acuminate apex. The fronds reached a length of more than
20 cm.[1702] Leckenby’s name _Pterophyllum medianum_[1703] was given
to a specimen from the Yorkshire coast and now in the Sedgwick Museum,
Cambridge, which, with _Pterophyllum angustifolium_, is clearly
identical with _Cycadites tenuicaulis_ Phillips. The specific name
_mediana_ frequently used[1704] for this type should be given up in
favour of the older term _tenuicaulis_. A species of similar habit is
described but not figured by Krasser[1705] as _N. Sturii_ from the Lunz
beds. _N. tenuicaulis_ is fairly common in the Middle Jurassic beds
near Scarborough and is recorded from the Kimmeridgian of Scotland
under the name _N. mediana_ (fig. 614, C)[1706].
_Nilssonia princeps_ (Oldham and Morris).
Oldham and Morris speak of _Pterophyllum princeps_[1707] as one of
the commonest plants in the Rajmahal beds in India. The fronds are
characterised by their large size and by the very broad oblong and
distally truncate pinnae with parallel and occasionally branched
veins. In the specimens figured by Oldham and Morris and Feistmantel
the pinnae are cut off at their bases (fig. 623), which form ridges
parallel to the rachis: this feature is not clearly shown in the
published drawings. By breaking some pieces of rock from a slab
containing figured specimens other pieces were found in which the
laminae of the bases of segments meet in the middle of the upper face
of the rachis. The pinnae vary in breadth from 1 cm. to 3·5 cm. and
reach a length of 8 cm.; the distal end is truncate, the lower edge
being strongly curved: the segments are slightly broadened at the base.
The veins are prominent and parallel, from 0·5 to 0·8 mm. apart. The
Rajmahal fronds described as _Pterophyllum Morrisianum_[1708] appear
to be indistinguishable from this species.
[Illustration: Fig. 623. _Nilssonia princeps._ (Slightly reduced;
Indian Geological Survey, Calcutta.)]
_Nilssonia Schaumburgensis_ (Dunker).
This species, first described as _Pterophyllum Schaumburgense_[1709]
from the Wealden of Germany, affords a good illustration of a small
type of frond closely resembling the much larger species _N. compta_.
Examples from English Wealden rocks seldom exceed 1 cm. in breadth and
are often much narrower; the linear lamina is almost entire or divided
into short and broad truncate segments of unequal breadth: the veins
are parallel and simple. For figures of this species, recorded from
different European localities and from Japan, reference should be made
to the accounts by Schenk[1710], Nathorst, Yokoyama, Yabe, and Fontaine.
=CTENIS.= Lindley and Hutton.
The genus _Ctenis_[1711] was founded on a piece of pinnate frond
from the Middle Jurassic rocks of the Yorkshire coast previously
figured by Phillips as _Cycadites sulcicaulis_. Lindley and Hutton
regarded the plant as probably Cycadean and proposed to apply the name
_Ctenis_ to all leaves having the general characters of Cycadeae, but
with ‘the veins connected by forks or transverse bars.’ While many
authors have accepted _Ctenis_ as a Cycadean genus, by others[1712]
it has been placed among the Ferns, on the ground that some small
circular elevations on the lamina of the segments of certain species
are believed to be sori or sporangia. Since Ettingshausen[1713]
and Schenk[1714] first noticed this feature Raciborski[1715] has
figured several examples from Poland and Staub[1716] records similar
circular bodies on a Liassic Hungarian species. In no single instance
have sporangia been found. Nathorst[1717] proposed the designation
_Anthrophyopsis_ (because of the resemblance of the lamina in form
and venation to the leaves of the Fern _Anthrophyum_) for some
Rhaetic specimens from Scania, but as they were subsequently found
to be segments of a pinnate frond he adopted the name _Ctenis_. An
example in the Manchester Museum[1718] (fig. 624) from Yorkshire,
mentioned by Nathorst in an early paper as probably a new species of
_Anthrophyopsis_, afforded good preparations of the cuticle (fig.
625) which revealed the existence of circular elevations on the outer
walls of the epidermal cells: these may explain the nature of some at
least of the supposed sporangia. The walls of the epidermal cells
are straight. The name _Ctenis_ is applied to pinnate fronds which
are probably Cycadean though we have no evidence as to the nature of
the stem or the reproductive organs. _Ctenis_ fronds are among the
largest Cycadean leaves from Mesozoic floras; in _Ctenis hungarica_
Staub the frond is said to have reached a length of 2 met. and in other
species the dimensions exceed those of most pinnate leaves. The stout
rachis bears linear or broad-oblong pinnae attached at a wide angle
and varying considerably in size and shape; the pinnae are attached
by the whole base which is usually broadened and decurrent but in a
few cases slightly contracted (_e.g._ _C. Zeyschneri_ Rac.[1719]). For
some fronds bearing broad and basally narrowed segments Raciborski
proposed the name _Ctenidiopsis_ in distinction from _Euctenis_ which
he applies to the typical forms. The pinnae may be long and narrow
reaching a length of over 12 cm., or short and broad: in some cases the
frond would be more correctly described as deeply pinnatisect; the apex
of the segments is acute, bluntly rounded or truncate. Several veins
pass into the base of each pinna and pursue a course approximately
parallel to the edge of the lamina; a characteristic feature is the
occasional occurrence of oblique cross-connexions between the veins.
It is possible that in some species the pinnae had spinous margins
as in the pinnae of uncertain affinity figured by Fontaine[1720] as
_Encephalartopsis nervosa_ from the Potomac series. Our knowledge of
the epidermal cells is very meagre: in the specimen represented in fig.
625 the epidermal cells have straight walls and a central papilla. The
genus extends from Triassic to Upper Jurassic rocks.
[Illustration: Fig. 624. _Ctenis_ sp. Single pinna. (Manchester
Museum, No. 53.)]
[Illustration: Fig. 625. _Ctenis_ sp. The epidermis of the pinna
shown in fig. 624. A, surface-view; _p_, papillae; _s_, stomata. B,
side-view. (Manchester Museum, No. 53.)]
_Ctenis lunzensis_ Stur.
This species, first recorded by Stur from the Lunz Upper Triassic
flora, has recently been examined by Krasser[1721] and compared with
the Jurassic species _Ctenis sulcicaulis_ (Phill.) (= _C. falcata_
Lind. and Hutt.) and _C. Potocki_ Rac. No figures or detailed
descriptions have been published.
_Ctenis fallax_ Nathorst.
This Scanian Rhaetic type[1722], including _Anthrophyopsis
crassinervis_, _A. Nilssoni_, and probably _A. obovata_ Nath., is
characterised by very large obtusely pointed pinnae reaching at least
20 cm. in length and over 3 cm. in breadth. The veins are often 2 mm.
apart and form long polygonal meshes. Nathorst figures small circular
patches on the surface of the lamina. Raciborski[1723], on slender
evidence, refers a fragment from the Jurassic of Cracow to this species.
_Ctenis hungarica_ Staub.
A species[1724] characterised by very large fronds reaching 2 met.,
bearing broad linear pinnae almost at right-angles and attached to the
rachis by decurrent bases, attaining a length of 21 cm. and a breadth
at the base of the lamina of 3·5 cm. and 4 cm. a short distance from
the acute apex. The veins are parallel to the edge of the lamina, but
Staub does not appear to have seen distinct anastomoses. It is not
improbable that Staub’s species may be identical with _C. asplenioides_
(Ett.) from the Lias of Hungary, specimens of which are preserved in
the École des Mines, Paris.
_Ctenis asplenioides_ (Ettingshausen).
This species was first described by Ettingshausen[1725] from Liassic
strata in Austria as _Taeniopteris asplenioides_ and compared by him to
large simple fronds of _Asplenium nidus_ but distinguished by a deeply
dissected lamina. Schenk[1726] found that the veins anastomose and
adopted the name _Ctenis_. In habit very similar to _C. sulcicaulis_,
but the pinnae are much broader, exceeding 4 cm., and the veins are
3–5 mm. apart. Only the basal part of the segments is figured by
Ettingshausen. Specimens in the École des Mines, Paris, from Hungary
have pinnae nearly 40 cm. long and 2·5 cm. in breadth, the parallel
veins being connected by a few oblique branches. Both Ettingshausen
and Schenk speak of small circular sori on the lower epidermis,
though these are not figured nor were any sporangia obtained. This
species and other examples of large _Ctenis_ fronds are described by
Raciborski from Lower Jurassic rocks in Poland. He figures part of a
leaf of _C. Zeyschneri_[1727] 40 cm. long bearing alternate pinnae
approximately 10 cm. long and nearly 4 cm. broad, characterised by
obtuse apices, a decurrent lamina, and anastomosing veins closer
together (16–24 per 1 cm.) than those of _C. asplenioides_. In one
Polish specimen, _C. remotinervis_[1728], with pinnae 5 cm. broad the
lamina is represented in the upper part of the frond as continuous over
the face of the rachis, and—if the drawing is accurate—the frond in
this respect differs from typical examples of _Ctenis_ and agrees with
_Nilssonia_. A species of _Ctenis_ with broad pinnae is described by
Yokoyama[1729] from the Jurassic of China as _C. Kaneharai_.
_Ctenis sulcicaulis_ (Phillips).
This type[1730] is more familiar under the name _Ctenis falcata_
given to it by Lindley[1731], but if we follow Lester Ward[1732] in
strict observance of the rule of priority, a course from which I have
frequently deviated on the ground of long usage, the less familiar
designation must be adopted. Fronds pinnate; long and tapered linear
pinnae sometimes exceeding 12 cm. in length and 1 cm. in breadth
attached obliquely or almost at right-angles to a fairly broad rachis
(fig. 626). The lamina is broadest at the base and the lower margin is
strongly decurrent, tapering distally to an acute apex. The parallel
and frequently anastomosing veins diverge slightly in the basal region
of the pinnae. Though usually separate to the base, the laminae of
adjacent pinnae may be continuous as in a pinnatisect leaf[1733]. This
species is recorded also from North America, and fronds of similar
habit are figured by Fontaine[1734] from the Jurassic of Oregon as
_Ctenis orovillensis_: a fragment recorded from Jurassic rocks in
Afghanistan as _Ctenis_ sp. may belong to _C. sulcicaulis_[1735].
_Ctenis latifolia_ (Brongniart).
This species[1736], originally referred to _Taeniopteris_, was
transferred to _Ctenis_ as the result of the discovery of anastomosing
veins in the type-specimen in the Oxford Museum. The segments are
shorter and broader than in _C. sulcicaulis_ and very similar to those
of _C. orovillensis_ Font.
[Illustration: Fig. 626. _Ctenis sulcicaulis._ (British Museum, V.
9012.)]
_Ctenis_ sp.
The pinna shown in fig. 624 from the Jurassic beds in Yorkshire[1737]
is interesting as one of the few examples of the preservation of the
cuticular membrane. The straight or curved walls of the epidermal
cells agree with those of recent Cycads except _Stangeria_, and each
cell bears a large central papilla that gives to the lamina the finely
punctate appearance which has been regarded as evidence of sporangia.
The gaps in the cuticle probably mark the position of sunken stomata.
=PSEUDOCTENIS.= Seward.
This genus[1738] was established for certain pinnate fronds agreeing
in habit with _Ctenis sulcicaulis_ but distinguished by the almost
complete absence of any cross-connexions between the veins. Some of
the forms with narrow pinnae closely resemble species of _Zamites_,
the distinguishing feature being the decurrent lower margin of the
leaflets. Though such fronds might not unreasonably be included in
_Ctenis_, it is more convenient on the analogy of the occasional
occurrence of _Glossopteris_ fronds with very few anastomoses to employ
a distinctive designation.
[Illustration: Fig. 627. _Pseudoctenis eathiensis._ (British Museum,
No. V. 2744; ½ nat. size.)]
_Pseudoctenis eathiensis_ (Richards).
Some of the specimens on which this species[1739] is founded were
originally figured by Miller[1740] from Upper Jurassic strata in
Scotland and afterwards named by Richards[1741] _Zamites eathiensis_.
The general appearance of the fronds is very like that of _Ctenis
sulcicaulis_; the pinnae vary in breadth from about 3 mm. to 1·5 cm.;
they are attached at right-angles or, in the apical region, may be
almost parallel to the rachis. The longest pinna recorded is 17 cm.
and the lamina tapers to a slender apex; the veins are parallel and
occasionally forked, but cross-connexions are rare. The partially
petrified rachis of one specimen showed hypodermal stereome and some
secretory canals as in recent Cycads. The specimen from Wealden rocks
near Hastings (fig. 627), originally described as _Zamites_ sp.[1742],
is probably specifically identical with _Pseudoctenis eathiensis_.
The South African Wealden species, originally described by Tate as
_Palaeozamia Rubidgei_[1743], agrees closely with _Pseudoctenis_ and is
probably an example of that genus. This type bears a close resemblance
in the form of the frond to _Ctenophyllum grandifolium_ Font.[1744]
and _C. Wardi_[1745] Font. from American Trias and Jurassic rocks
respectively. _Pseudoctenis crassinervis_ Sew.[1746] is another Scotch
form with coarser veins.
A frond very similar in habit to _P. eathiensis_ is represented by
_Pseudoctenis ensiformis_ Halle[1747] from the Jurassic strata of
Graham Land originally referred by Nathorst to _Pterophyllum_. An
examination of the type-specimen in the Stockholm Museum revealed its
resemblance to the Scotch species _P. eathiensis_: a single anastomosis
was noticed in one of the pinnae. The broadly ensiform obtuse pinnae,
reaching a length of 7 cm. with a maximum breadth of 3 cm. at their
expanded bases, vary in breadth and are attached at right-angles to a
slender rachis. The veins, 1–1·5 mm. apart, are parallel and strong.
The varying breadth of the pinnae irrespective of their position on the
rachis is a distinctive feature. Halle draws attention to a resemblance
of this Antarctic species to _Ctenophyllum latifolium_ Font. a Potomac
type referred by Berry[1748] to the genus _Ctenopsis_ on the rather
slender ground that the veins are arranged in pairs. Berry in a
footnote expresses the opinion that _Ctenopsis_ is very closely related
to or possibly identical with _Pseudoctenis_.
If the bases of the pinnae in the specimen of _P. ensiformis_ figured
by Halle are complete, as they appear to be, the frond agrees very
closely with _Pterophyllum Carterianum_ Old. and Morr.[1749] from
India. A comparison of the Rajmahal specimen with Halle’s figure
leads me to regard the two fronds as probably identical. The veins in
the Indian species, which should also be referred to _Pseudoctenis_,
are prominent and from ·5 to 1 mm. apart; the base of the lamina is
slightly broadened and the veins curve downwards towards the rachis
in the lower decurrent portion. The other Indian type, _Pterophyllum
Morrisianum_[1750], with which Halle compares his species is, however,
not a _Pseudoctenis_ but should be included in _Nilssonia_ and is
probably identical with _Pterophyllum princeps_ Old. and Morr.
_Pseudoctenis Lanei_ Thomas.
This species[1751], recently described from Middle Jurassic beds at
Marske, Yorkshire, has narrower linear lanceolate pinnae. The linear
pinnae reach a length of 10 cm. and a breadth of 9 mm. The veins
are numerous, 10 in a breadth of 6 mm., and only one cross-vein was
noticed. In the decurrent lower edge of the laminae the fronds are
identical with _Ctenis sulcicaulis_. A very good example of this
species[1752] in the York Museum is reproduced by Mr Thomas in his
account of Cleveland Jurassic plants.
_Pseudoctenis Balli_ (Feistmantel).
A species described originally by Feistmantel[1753] as _Anomozamites
Balli_ from the Barakar group of the Damuda series and afterwards
transferred to the genus _Platypterygium_, characterised by broadly
linear segments of unequal breadth attached obliquely or at
right-angles to a slender rachis. The apices of the segments though
usually imperfect appear to be truncate; the bases of the pinnae
are decurrent by their lower edge. The veins are approximately 3
per millimetre; they are generally forked at the base and in one or
two places show cross-connexions. In the middle of the frond the
narrow rachis is exposed but in the apical region it is covered by
the laminae. The occurrence of two divergent pinnae at the apex of
the frond is a feature met with also in _Ctenis sulcicaulis_. This
description is based on an examination of the specimens figured by
Feistmantel.
III. +Cycadean Fronds which cannot be assigned to a family-position.+
=SPHENOZAMITES.= Brongniart.
This name was proposed by Brongniart[1754] as a subgenus of
_Otozamites_ denoting pinnate fronds bearing leaflets without an
auriculate base: he suggested that the subgenus might eventually be
raised to generic rank and this was done by Zigno[1755] though in too
wide a sense. In the case of _Otozamites Beani_ (Lind. and Hutt.),
quoted by Brongniart in illustration of _Sphenozamites_, the latter
designation is inapplicable as the pinnae are auriculate. Another
species, _Zamites undulatus_ Sternb., to which Brongniart applied his
new subgeneric term, is probably identical with _Otozamites acuminatus_
(L. and H.)[1756].
Although the distinction between _Sphenozamites_ and _Otozamites_ is
often ill defined the former name may be conveniently adopted for
pinnate fronds similar to those of _Zamia Skinneri_ and some species
of _Encephalartos_ characterised by leaflets of an asymmetrical,
obovate, or rhomboidal form with a contracted or cuneate base and
numerous branched divergent veins. Nothing is known of the structure or
reproductive organs of _Sphenozamites_, and the genus, though serving
a useful descriptive purpose, is founded solely on form, and in the
absence of other data it would be rash to assume that its use implies
close natural affinity. In the case of many other genera of Cycadean
fronds there is additional evidence of relationship, but this is not
the case with _Sphenozamites_. The pinnae resemble those of such recent
Cycadean fronds as _Zamia Skinneri_ and _Z. muricata_. The genus ranges
from Lower Permian to Jurassic rocks.
_Sphenozamites Rochei_ Renault.
This species[1757], from the Lower Permian of the Autun district, is
founded on a pinnate frond bearing alternate pinnae, 2·5 × 1 cm., with
an asymmetrical oblong lamina attached obliquely near the edge of
the rachis with a cuneate base slightly decurrent below and a broadly
rounded apex; the veins dichotomise once or twice as they diverge
from the narrow base (fig. 628). The pinnae resemble the leaflets of
_Noeggerathia foliosa_ Sternb. and are similar in shape to those of the
Jurassic species _Sphenozamites Geylerianus_ Zig.
[Illustration: Fig. 628. _Sphenozamites Rochei._ (After Renault; nat.
size.)]
[Illustration: Fig. 629. _Sphenozamites Belli._ (Oxford Museum; nat.
size.)]
_Sphenozamites Belli_ Seward.
This Middle Jurassic species from Stonesfield[1758] is founded on
detached pinnae possibly identical with a specimen figured by Buckman
as _?Naiadea obtusa_[1759]. The pinnae are wedge-shaped, tapering
gradually to an acute apex and attached by a narrow base: the leaflet
shown in fig. 629 is 9 cm. long; the veins are numerous and more
divergent than in some leaves of similar form referred to the genus
_Podozamites_. With this species may be compared several Italian
Jurassic specimens described by Zigno[1760] as four distinct species
but more appropriately assigned to a single type _S. Geylerianus_.
An examination of Zigno’s fronds in the Padua Museum, which he named
_S. Rossii_, leads me to regard the irregularly serrate edge of the
pinnae as the result of tearing of an originally entire lamina and
to compare the specimens with _Otozamites Beani_ (L. and H.). An
imperfect ovoid pinna recalling _S. Belli_ is figured by Newberry
from the Rhaetic of Honduras as _Sphenozamites robustus_[1761]. A
French Upper Jurassic species figured by Saporta as _Sphenozamites
latifolius_ bears a very close resemblance in the form of the leaflets
to the Wealden plant _Sewardia latifolia_[1762]. Kurtz records the
occurrence of _Sphenozamites_, _S. Geinitzianus_, from Rhaetic strata
in Argentina[1763], but I have not seen any figures of this species.
=PLAGIOZAMITES=. Zeiller.
The name _Plagiozamites_ was proposed by Zeiller[1764] for some pinnate
fronds and detached leaflets from the Stephanian of Commentry and the
Lower Permian of the Vosges. The better preservation of the Vosges
material enabled him to recognise certain features which led to the
substitution of _Plagiozamites_ for _Zamites_, the name originally
employed by Renault for the Commentry specimens. _Plagiozamites_ bears
a superficial resemblance to _Zamites_ and _Otozamites_ and differs
but little from _Sphenozamites_ and _Noeggerathia_; it stands for
pinnate fronds bearing ovate pinnae with a sub-amplexicaul oblique
attachment to the rachis as is clearly shown in the species _P.
Planchardi_ (Ren.)[1765]. In the case of Palaeozoic fronds assigned to
the Cycadophyta on the ground of the resemblance of their pinnae to
those of undoubted Cycadean species, it is particularly important to
recognise the fact that decisive evidence as to systematic position is
lacking. We know nothing of the stem, the reproductive organs, or the
epidermal and stomatal characters of _Plagiozamites_, and it is by no
means certain that the genus is a true representative of the group in
which it is provisionally included.
_Plagiozamites Planchardi_ (Renault).
Fronds pinnate; pinnae ovate-lanceolate reaching 5 cm. in length and
1·6 cm. in breadth, inserted obliquely on the rachis, but not along
a line parallel to the long axis of the rachis as in _Zamites_, and
partially embracing it: the edge of the lamina is finely denticulate;
veins slightly divergent and occasionally branched. The leaflets are
narrow and more acute than those of _Noeggerathia_ and _Sphenozamites
Rochei_ Ren. _Plagiozamites_ is recorded from the Stephanian of
Commentry, the Coal Measures of Manchuria[1766], and the Lower Permian
of the Vosges. Renault described six species of _Zamites_ from
Commentry all, except _Z. carbonarius_, based on detached pinnae.
The type-specimen of _Z. carbonarius_ consists of a piece of stout
rachis bearing ovate acute pinnae, 2·2 × 1 cm. Potonié[1767], who
refers a piece of pinnate frond from the Permian of Thuringia to
_Z. carbonarius_, includes the other species of Renault under that
name. Whether or not the differences in the venation and form of the
pinnae are of specific significance cannot be definitely settled
without better material, but the important point is that these
Permo-Carboniferous fronds are sufficiently distinct from _Zamites_
to be placed in a separate genus. _Plagiozamites carbonarius_ is
recorded also by Zalessky[1768] from the Permian of Manchuria though
the examples figured do not afford satisfactory evidence of the
mode of insertion of the segments on the rachis. _P. Planchardi_
has recently been recorded from the Coal Measures of Maryland; the
discovery is interesting both on phytogeographical grounds and as
the first satisfactory record of a Palaeozoic Cycadophyte from North
America[1769].
=Cycadorachis.= Saporta.
The employment of this generic name may serve a useful purpose if used
for specimens, whether preserved as petrifactions or impressions,
believed to be portions of Cycadean frond-axes, but which in the
absence of pinnae cannot be assigned to one of the recognised genera
of fronds. Saporta[1770] describes two species from Kimmeridgian beds
in France, _Cycadorachis abscissa_ and _C. armata_: the first may be
the winged base of a Cycadean petiole, but it agrees equally well with
the broad base of an Osmundaceous leaf and should not be referred to
a genus implying affinity with a particular class. The other species,
_C. armata_, is probably a piece of a spinous axis like that of the
Wealden plant _Sewardia latifolia_ (Sap.). A fragment figured by Fliche
and Bleicher[1771] from the Jurassic of Nancy as _C. tuberculata_ is
another example of a fossil which cannot be referred with any certainty
to the Cycads.
Dr Stopes[1772], inadvertently overlooking the previous institution
of _Cycadorachis_, has recently proposed the name _Cycadeorachis_ for
pinnately branched rachises of Cycadean fronds which, ‘while indicating
the general character of the frond, do not show the shape of the pinnae
well enough to be associated with any of the many foliage-genera.’
LIST OF WORKS REFERRED TO IN THE TEXT
(+Volumes III. and IV.+)
[_With a few exceptions this list does not include books and papers
given in the Bibliographies in volumes I. and II._]
The following are some of the Bibliographies which students will
find useful for additional references:—Geological Literature added
to the Geological Society’s Library, published from time to time
by the Society; Prof. Zeiller’s lists in the ‘Revue Générale de
Botanique’ (Paris); lists given by Arber in the ‘Progressus Rei
Botanicae’ (Leiden), vol. +i.+ Heft i. p. 218, 1907; Jongman’s ‘Die
Palaeobotanische Literatur’ (Jena), 1910–13; also the International
Catalogue of Scientific Literature (Botany and Geology). For the
Literature dealing with Cretaceous plants the student should refer to
Dr Marie Stopes’ ‘Cretaceous Flora’ +i.+ and +ii.+ (British Museum
Catalogues, 1913, 1915).
The dates of books published in parts given in the footnotes to this
volume are as a rule those of the concluding part. For the dates of
separate parts of books relating to Palaeozoic floras the student is
referred to Prof. Zeiller’s valuable list at the end of the ‘Flore
Fossile du Bassin Houiller de Valenciennes.’ Useful bibliographies of
the writings of Saporta, Heer, and Ettingshausen have been compiled by
Zeiller (96), Malloizel and Zeiller (N.D.), and Krasser (97).
=Aase, Hannah C.= (15) Vascular anatomy of the megasporophylls of
Conifers. _Botanical Gazette_, vol. +lx.+ p. 277.
=Affourtit, M. F. A.= and =H. C. C. La Rivière.= (15) On the ribbing of
the seeds of _Ginkgo_. _Annals of Botany_, vol. +xxix.+ p. 591.
=Andersson, J. G.= (10) Die Veränderungen des Klimas seit dem Maximum
der letzten Eiszeit. (Collection of papers published by the Int.
Geol. Congress; edited by J. G. Andersson.) _Stockholm_.
=Andrews, E. B.= (75) Descriptions of Fossil Plants from the Coal
Measures of Ohio. _Geol. Surv. Ohio_.
=Antevs, E.= (14) _Lepidopteris Ottonis_ (Göpp.) Schimp. and
_Anthotithus Zeilleri_ Nath. _K. Svensk._ _Vetenskapsakad. Hand._
Bd. +li.+ No. 7.
—— (14²) The Swedish Species of _Ptilozamites_ Nath. _Ibid._ Bd.
+li.+ No. 10.
=Arber, Agnes.= (See also Robertson, A.) (10) On the structure of the
Palaeozoic seed _Mitrospermum compressum_ (Will.). _Ann. Bot._
vol. +xxiv.+ p. 491.
—— (14) A note on _Trigonocarpus_. _Ibid._ vol. +xxviii.+ p. 195.
=Arber, E. A. Newell.= (02) Notes on the Binney collection
of Coal-Measure Plants. Pt. iii. The type-specimens of
_Lyginodendron oldhamium_ (Binney). _Proc. Camb. Phil. Soc._ vol.
+xi.+ pt. iv. p. 281.
—— (03) On the roots of _Medullosa anglica. Ann. Bot._ vol. +xvii.+
p. 425.
—— (03²) Discussion on Dr Kurtz’s paper (1903). _Quart. Journ. Geol.
Soc._ vol. +lix.+ p. 26.
—— (04) _Cupressinoxylon Hookeri_ sp. nov. a large silicified tree
from Tasmania. _Geol. Mag._ [+v+], vol. +i.+ p. 7.
—— (05) On some new species of _Lagenostoma_, a type of
Pteridospermous seed from the Coal Measures. _Proc. R. Soc._ vol.
+lxxi.+ B, p. 245.
—— (07) On Triassic species of the genera _Zamites_ and
_Pterophyllum_, types of fronds belonging to the Cycadophyta.
_Trans. Linn. Soc._ vol. +vii.+ pt. vii. p. 109.
—— (08) On a new Pteridosperm possessing the _Sphenopteris_ type of
foliage. _Ann. Bot._ vol. +xxii.+ p. 57.
—— (09) On the Fossil Plants of the Waldershare and Fredville series
of the Kent Coalfield. _Quart. Journ. Geol. Soc._ vol. +lxv.+ p.
21.
—— (09²) On the affinities of the Triassic plant _Yuccites
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11.
—— (12) On _Psygmophyllum majus_ sp. nov. from the Lower
Carboniferous rocks of Newfoundland, together with a Revision of
the genus and Remarks on its affinities. _Trans. Linn. Soc._ vol.
+vii.+ p. 391.
—— (12²) Fossil Plants from the Kent Coalfield. _Geol. Mag._ [+v+],
vol. +ix.+ p. 97.
—— (13) A preliminary note on the Fossil Plants of the Mount Potts
beds, New Zealand, collected by Mr D. G. Lillie, Biologist to
Capt. Scott’s Antarctic Expedition in the “Terra Nova.” _Proc. R.
Soc._ vol. +lxxxvi.+ p. 344.
—— (13²) The structure of _Dadoxylon Kayi_. _Quart. Journ. Geol.
Soc._ vol. +lxix.+ p. 454.
—— (14) A Revision of the Seed impressions of the British Coal
Measures. _Ann. Bot._ vol. +xxviii.+ p. 81.
—— (14²) On the Fossil Flora of the Kent Coalfield. _Quart. Journ.
Geol. Soc._ vol. +lxx.+ p. 54.
=Arber, E. A. Newell and J. Parkin=. (07) On the origin of Angiosperms.
_Journ. Linn. Soc._ vol. +xxxviii.+ p. 29.
—— (08) Studies on the Evolution of the Angiosperms. _Ann. Bot._
vol. +xxii.+ p. 489.
=Arnoldi, W.= (01) Beiträge zur Morphologie einiger Gymnospermen.
_Bull. Nat. Moscow_, No. 4, 1900.
=Bailey, I. W.= (09) The structure of the wood in the Pineae. _Bot.
Gaz_. vol. +xlviii.+ p. 47.
—— (11) A Cretaceous _Pityoxylon_ with marginal tracheids. _Ann.
Bot._ vol. +xxv.+ p. 315.
=Baily, W. H.= (69) Notice of Plant-remains from Beds interstratified
with the Basalts in the county of Antrim. _Quart. Journ. Geol.
Soc._ vol. +xxv.+ p. 357.
=Bain, F.= and =Sir W. Dawson=. (85) Notes on the Geology and Fossil
Flora of Prince Edward Island. _Canadian Rec. Sci._ vol. +i.+
(1884–85) p. 154.
=Baker, R. T.= and =H. C. Smith=. (10) Research of the Pines on
Australia. _Dpt. Public Instruction_, _Tech. Educ. Ser._ No. 16.
_Sydney_.
=Bancroft, Nellie.= (13) On some Indian Jurassic Gymnosperms and
_Rhexoxylon africanum_, a new Medullosan stem. _Trans. Linn.
Soc._ vol. +viii.+ pt. ii. p. 69.
—— (14) Pteridosperm Anatomy and its relation to that of the Cycads.
_New Phyt._ vol. +xiii.+ p. 41.
=Barber, C. A.= (92) On the nature and development of the corky
excrescences on stems of _Zanthoxylum_. _Ann. Bot._ vol. +vi.+ p.
155.
—— (98) _Cupressionoxylon vectense_; a fossil Conifer from the Lower
Greensand of Shanklin, in the Isle of Wight. _Ann. Bot._ vol.
+xii.+ p. 329.
=Bartholin, C. T.= (94) Nogle i den bornholmske Juraformation
forekommende Planteforsteninger. _Bot. Tidskrift_ (Copenhagen),
Bd. +xix.+ p. 87.
=Bartlett, A. W.= (13) Note on the occurrence of an abnormal
bisporangiate strobilus of _Larix europaea_ DC. _Ann. Bot._ vol.
+xxvii.+ p. 575.
=Bassler, H.= (16) A Cycadophyte from the North American Coal Measures.
_Amer. Journ. Sci._ vol. +xlii.+ p. 21.
=Bayer, A.= (08) Zur Deutung der weiblichen Blüten der Cupressineen
nebst Bemerkungen über _Cryptomeria_. _Beiheft Bot. Cent._ Bd.
+xxiii.+ Abt. +i.+ p. 27.
=Beissner, L.= (91) Handbuch der Nadelholzkunde. _Berlin._
=Bennett, J. J.= and =R. Brown.= (52) Plantae Javanicae rariores.
_London_, 1838–52.
=Benson, Margaret.= (08) On the contents of the pollen-chamber of a
specimen of _Lagenostoma ovoides_. _Bot. Gaz._ vol. +lv.+ p. 409.
—— (12) _Cordaites Felicis_, sp. nov., a Cordaitean leaf from the
Coal Measures of England. _Ann. Bot._ vol. +xxvi.+ p. 202.
—— (14) _Sphaerostoma ovale_ (_Conostoma ovale_ et _intermedianum_,
Williamson), a Lower Carboniferous ovule from Pettycur,
Fifeshire, Scotland. _Trans. R. Soc._ Edinburgh, vol. +l.+ pt. i.
No. i. p. 1.
=Benson, M.= and =E. J. Welsford=. (09) The morphology of the ovule
and female flower of _Juglans regia_ and of a few allied genera.
_Ann. Bot._ vol. +xxiii.+ p. 623.
=Berger, R.= (48) De fructibus et seminibus ex formatione
lithanthracum. _Diss. Inaug. Vratislaviae._
=Bergeron, J.= (84) Note sur les strobiles du _Walchia piniformis_.
_Bull. soc. géol. France_ [3], Tome +xii.+ p. 583.
=Berridge, E. M.= (11) On some points of resemblance between Gnetalean
and Bennettitean seeds. _New Phyt._ vol. +x.+ p. 140.
—— (12) The structure of the female strobilus in _Gnetum Gnemon_.
_Ann. Bot._ vol. +xxvi.+ p. 987.
=Berridge, Emily M.= and =Elizabeth Sanday=. (07) Oogenesis and
embryogeny in _Ephedra distachya_. _New Phyt._ vol. +vi.+ p. 127.
=Berry, E. W.= (03) The Flora of the Matawan Formation. _Bull. New York
Bot. Gard._ vol. +iii.+ No. 9, p. 45.
—— (05) Additions to the fossil Flora from Cliffwood. _Bull. Torrey
Bot. Club_, vol. +xxxii.+ p. 43.
—— (06) Contributions to the Mesozoic Flora of the Atlantic Coastal
Plain. I. _Ibid._ vol. +xxxiii.+ p. 33.
—— (07) Coastal Plain Amber. _Torreya_, vol. +vii.+ p. 4.
—— (07²) Contributions to the Pleistocene Flora of North Carolina.
_Journ. Geol._ vol. +xv.+ No. 4, p. 338.
—— (08) Some Araucarian remains from the Atlantic Coastal Plain.
_Bull. Torrey Bot. Club_, vol. +xxxv.+ p. 249.
—— (08²) A Mid-Cretaceous species of _Torreya_. _Amer. Journ. Sci._
vol. +xxv.+ p. 382.
—— (09) A Miocene Flora from the Virginian Coastal Plain. _Journ.
Geol._ vol. +xvii.+ p. 19.
—— (09²) Pleistocene Swamp deposits in Virginia. _Amer. Nat._ vol.
+xliii.+ p. 432.
—— (10) A revision of the Fossil Plants of the genus _Nageiopsis_ of
Fontaine. _Proc. U. S. Nat. Mus._ vol. +xxxviii.+ p. 185.
—— (10²) The epidermal characters of _Frenelopsis ramosissimus_.
_Bot. Gaz._ vol. +l.+ p. 305.
—— (10³) Additions to the Pleistocene Flora of New Jersey.
_Torreya_, vol. +x.+ p. 261.
—— (10⁴) Contributions to the Mesozoic Flora of the Atlantic Coastal
Plain. V. North Carolina. _Bull. Torrey Bot. Club_, vol.
+xxxvii.+ p. 181.
—— (11) The Lower Cretaceous deposits of Maryland. (Berry, Clark,
and Bibbin.) _Maryland Geol. Surv._
—— (11²) A Lower Cretaceous species of Schizaeaceae from Eastern
North America. _Ann. Bot._ vol. +xxv.+ p. 193.
—— (11³) The Flora of the Raritan Formation. _Geol. Surv. New
Jersey, Bull._ 3.
—— (11⁴) A Revision of several genera of Gymnospermous plants from
the Potomac group in Maryland and Virginia. _Proc. U. S. Nat.
Mus._ vol. +xl.+ p. 289.
—— (12) The age of the plant-bearing shales of the Richmond
coal-field. _Amer. Journ. Sci._ vol. +xxxiv.+ p. 224.
—— (12²) Notes on the genus _Widdringtonites_. _Bull. Torr. Bot.
Club_, vol. +xxxix.+ p. 341.
—— (12³) Contributions to the Mesozoic Flora of the Atlantic Coastal
Plain. VII. Texas. _Bull. Torrey Bot. Club_, vol. +xxxix.+ p.
387.
—— (12⁴) Pleistocene plants from the Blue Ridge in Virginia. _Amer.
Journ. Sci._ vol. +xxxiv.+ p. 218.
—— (14) The Upper Cretaceous and Eocene floras of South Carolina and
Georgia. _U. S. Geol. Surv. Professional papers_, No. 84.
—— (15) The Mississippi River Bluffs at Columbus and Hickman,
Kentucky, and their Fossil Flora. _Proc. U. S. Nat. Mus._ vol.
+xlviii.+ p. 293.
—— (16) The Geological history of Gymnosperms. _The Plant World_,
vol. +xix.+ p. 27.
=Bertrand, C. E.= (74) Anatomie comparée des tiges et des feuilles chez
les Gnétacées et les Conifères. _Ann. Sci. nat._ [v], vol. +xx.+
p. 5.
—— (83) Note sur le genre _Vesquia_, Taxinée fossile du Terrain
Aachénien de Tournai. _Bull. soc. bot. France_ [3], Tome +v.+ p.
293.
—— (89) Les Poroxylons végétaux fossiles de l’époque houillière.
_Ann. soc. Belg. de Microscopie_, Tome +xiii.+ Fasc. i.
—— (98) Remarques sur la structure des grains de pollen de
_Cordaites_. _Assoc. Franç. pour l’avanc. des Sci. Nantes_
(1898), p. 436.
—— (07) Les caractéristiques du genre _Rhabdocarpus_ d’après les
préparations de la collection B. Renault. _Bull. soc. bot._ [4],
Tome +vii+, p. 654.
—— (07²) Les caractéristiques du genre _Diplotesta_ de Brongniart.
_Bull. soc. bot. France_ [4], tome +vii.+ p. 388.
—— (07³) Les caractéristiques du genre _Leptocaryon_ de Brongniart.
_Ibid._ p. 452.
—— (07⁴) Les caractéristiques du genre _Taxospermum_ de Brongniart.
_Ibid._ p. 213.
—— (07⁵) Remarques sur le _Taxospermum angulosum_. _Compt. rend.
d’assoc. Franç. pour l’avanc. des sci._ (Reims, 1907), p. 410.
—— (08) Les caractéristiques du _Cycadinocarpus angustodunensis_ de
B. Renault. _Bull. soc. bot. France_ [4], tome +viii.+ p. 326.
—— (08²) Les caractéristiques du genre _Cardiocarpus_ d’après les
graines silicifiées étudiées par Ad. Brongniart et B. Renault.
_Ibid._ p. 391.
—— (08³) La spécification des _Cardiocarpus_ de la collection B.
Renault. _Ibid._ p. 454.
—— (09) Sur le genre _Compsotesta_ de Ad. Brongniart. _Ann. Jard.
Bot. Buit._ [2], suppl. 3.
—— (11) Le Bourgeon femelle des _Cordaites_. _Nancy._
=Bertrand, C. E.= et =B. Renault=. (82) Recherches sur les Poroxylons.
_Arch. bot. du Nord de la France_, vol. +ii.+ p. 243.
=Bertrand, P.= (08) Sur les stipes de _Clepsydropsis_. _Compt. Rend._,
Nov. 16, 1908.
—— (11) Structure des stipes _d’Asterochlaena laxa_ Sterzel. _Mém.
soc. géol. Nord_, Tome +vii.+ i.
—— (13) Les Fructifications de Neuroptéridées recueillies dans le
terrain houiller du Nord de la France. _Ann. soc. géol. Nord_,
Tome +xlii.+ p. 113.
—— (14) État actuel de nos Connaissances sur les Genres ‘Cladoxylon’
et ‘Steloxylon.’ _Compt. Rend. de l’assoc. franç. pour
l’Avancement des Sciences_ (Havre, 1914), p. 446.
=Beust, F.= (85) Untersuchung über fossile Hölzer aus Grönland. _Neue
Denksch. allgem. Schweiz. Ges. gesammt. Naturwiss_. Bd. +xxix.+
=Binney, E. W.= (66) On Fossil wood in calcareous nodules found in the
upper foot coal near Oldham. _Proc. Lit. Phil. Soc. Manchester_,
vol. +v.+ p. 113.
=Bleicher and Fliche=. (92) Contribution à l’étude des Terrains
Tertiaires d’Alsace. _Bull. soc. géol. France_ [3], Tome +xx.+ p.
375.
=Bodenbender, W.= (96) Beobachtungen über Devon- und Gondwana-Schichten
in der Argentinischen Republik. _Zeitsch. Deutsch. geol. Ges._
Bd. +xlviii.+ p. 743.
—— (02) Contribucion al Conocimiento de la Precordillera de San Juan
de Mendoza. _Bot. Acad._ _Nac. Cienc. Cordoba_, vol. +xvii.+ p.
203.
=Boodle, L. A.= (15) Concrescent and solitary Foliage-leaves in
_Pinus_. _New Phyt._ vol. +xiv.+ p. 19.
=Boodle, L. A.= and =W. C. Worsdell=. (94) On the comparative anatomy
of the Casuarineae, with special reference to the Gnetaceae and
Cupuliferae. _Ann. Bot._ vol. +viii.+ p. 231.
=Boulay=. (79) Recherches de paléontologie végétale dans le terrain
houiller du Nord de la France. _Ann. soc. scient. Bruxelles_,
ann. iv. pt. 2, 1880.
—— (87) Notice sur la Flore tertiaire des environs de Privas
(Ardiche). _Bull. soc. bot. France_, Tome +xxxiv.+ p. 227.
—— (88) Notice sur les Plantes fossiles des grès tertiaires de
Saint-Saturnin (Marne et Loire). _Journ. Bot. Ann._ 2, p. 921.
=Bower, F. O.= (81) On the germination and histology of the seedlings
of _Welwitschia mirabilis_. _Quart. Journ. Micr. soc._ vol.
+xxi.+ pp. 15, 571.
—— (82) The germination and embryogeny of _Gnetum Gnemon_. _Ibid_.
vol. +xxii.+ [N.S.], p. 277.
—— (84) On the structure of _Rhynchopetalum montanum_. _Journ. Lin.
Soc._ vol. +xx.+ p. 440.
—— (12) Studies in the Phylogeny of the Filicales. II. _Lophosira_,
and its relation to the Cyatheoideae and other Ferns. _Ann. Bot._
vol. +xxvi.+ p. 269.
=Bowerbank, J. S.= (40) History of the Fossil fruits and seeds of the
London Clay. _London_.
=Braun, A.= (75) Die Frage nach der Gymnospermie der Cycadeen.
_Monatsber. K. Preuss. Akad. Wiss. Berlin_, p. 289.
—— (75²) Die Diagnosen dreier im Jahre 1873 von G. Wallis in Neu
Granada entdeckter Cycadeen. _Ibid_. p. 376.
=Braun, C. F. W.= (43) Beiträge zur Petrefactenkunde Bayreuth (Graf zu
Münster), Heft +vi.+ _Bayreuth_.
—— (47) Die Fossile Gewächse aus den Grenzschichten zwischen dem
Lias und Keuper des neu aufgefundenen Pflanzenlagers in dem
Steinbrüche von Veitlahm bei Culmbach. _Flora_, p. 81.
—— (49) Beiträge zur Urgeschichte der Pflanzen. VI. _Weltrichia_
eine neue Gattung fossiler Rhizantheen. _Progr. iii. Jahresber.
K. Kreis-Landwirthsch. und Gewerbschule zu Bayreuth_.
=Brauns, D.= (66) Der Sandstein bei Seinstedt unweit des Fallsteins und
die in ihm vorkommenden Pflanzenreste. _Paleont_. Bd. +ix.+ p. 47.
=Brenchley, Winifred E.= (13) On Branching specimens of _Lyginodendron
Oldhamium_ Will. _Journ. Linn. Soc_. vol. +xli.+ p. 349.
=Bristow, H. W.= (62) The Geology of the Isle of Wight. _Mem. Geol.
Surv. Great Britain_.
=Brongniart, A.= (25) Observations sur les végétaux fossiles renfermés
dans les grès de Hoer en Scanie. _Ann. Sci. nat._ vol. +iv.+ p.
200.
—— (28) Essai d’une Flore du grès bigarré. _Ann. Sci. nat._ vol.
+v.+ p. 435.
—— (33) Notice sur une Conifère fossile du terrain d’eau douce de
l’île d’Iliodroma. _Ann. Sci. nat._ tome +xxx.+ p. 175.
—— (74) Études sur les graines fossiles trouvées à l’état silicifié
dans le terrain Houiller de Saint Étienne. _Ann. Sci. nat._ tome
+xx.+ [5], p. 234.
—— (81) Recherches sur les graines fossiles silicifiées. _Paris_.
=Bronn, H. G.= (58) Beiträge zur triassischen Schiefer von Raibl.
_Neues Jahrb. Min_. p. 129.
=Brooks, F. T.= and =A. Sharples=. (14) Pink disease. _Bull. No._ 21,
_Depart. Agric. Fed. Malay States_.
=Brooks, F. T.= and =W. Stiles=. (10) The structure of _Podocarpus
spinulosus_ (Smith) R. Br. _Ann. Bot._ vol. +xxiv.+ p. 305.
=Buchman, J.= (45) Outline of the Geology of the neighbourhood of
Cheltenham (in collaboration with R. I. Murchison and H. E.
Strickland). _London_.
=Buckland, W.= (28) On the Cycadeoideae, a Family of Fossil Plants
found in the Oolite quarries of the Isle of Portland. _Trans.
Geol. Soc_. [2], vol. +ii.+ p. 395.
—— (37) Geology and Mineralogy considered with reference to Natural
Theology. _London_.
=Burckhardt, C.= (11) Bemerkungen zu einigen Arbeiten von W. Gothan und
A. G. Nathorst. _Cent. Min. Geol.; Paleont_. p. 442.
=Burgestein, A.= (06) Zur Holzanatomie der Tanne, Fichte und Lärche.
_Ber. deutsch. Bot. Ges._ Bd. +xxiv.+ Heft +vi.+ p. 295.
—— (08) Vergleichende Anatomie des Holzes der Koniferen.
_Wiesner-Festschrift, Wien_.
=Burlingame, L.= (08) The staminate cone and male gametophyte of
_Podocarpus. Bot. Gaz._ vol. +xlvi.+ p. 161.
—— (13) The Morphology of _Araucaria brasiliensis. Bot. Gaz._ vol.
+lv.+ p. 97.
—— (15) The Morphology of _Araucaria brasiliensis. Ibid_. vol.
+lix.+ p. 1.
—— (15²) The Origin and Relationships of the Araucarians. _Ibid_.
vol. +lx.+ p. 1.
=Butterworth, J.= (97) Some further investigations of Fossil seeds
of the genus _Lagenostoma_ (Williamson) from the Lower Coal
Measures, Oldham. _Mem. Proc. Manchester Lit. and Phil. Soc._
vol. +xli.+ ix. p. 1.
=Caldwell, O. W.= (07) _Microcycas calocoma. Bot. Gaz._ vol. +xliv.+ p.
118.
=Caldwell, O. W.= and =C. F. Baker=. (07) The identity of _Microcycas
calocoma_. _Ibid_. vol. +xliii.+ p. 130.
=Cambier, R.= et =A. Renier=. (10) _Psygmophyllum Delvali_ n. sp. du
Terrain houiller de Charleroi. _Ann. soc. géol. Belg_. Tome +ii.+
p. 23. (_Mém. in 4to_.)
=Capellini, G.= and =Conte E. Solms-Laubach=. (92) I Tronchi di
Bennettitee dei Musei Italiani. _Mem. Reale Acad. Sci. Istit.
Bologna_ [5], tom. +ii.+ p. 161.
=Carano, E.= (04) Contribuzione alla conoscenza della Morfologia e
dello sviluppo del fascio vascolare delle foglie delle Cicadacee.
_Ann. di Bot_. vol. +i.+ p. 109 (Rome).
=Carpentier, A.= (11) Sur quelques fructifications et inflorescences du
Westphalien du Nord de la France. _Rev. Gén. Bot_. tome +xxiii.+
p. 1.
—— (13) Contribution à l’étude du Carbonifère du Nord de la France.
_Mém. soc. géol. du Nord_, tome +vii.+ ii. p. 1.
=Carruthers, W.= (66) On Araucarian cones from the Secondary beds of
Britain. _Geol. Mag_. vol. +iii.+ p. 249.
—— (66²) On some fossil Coniferous fruits. _Ibid_. vol. +iii.+ p.
534.
—— (67) On _Cycadeoidea Yatesii_ sp. nov. a fossil Cycadean stem
from the Potton sands, Bedfordshire. _Ibid_. vol. +iv.+ p. 199.
—— (67²) On Gymnospermous Fruits from the Secondary rocks of
Britain. _Journ. Bot_. vol. +v.+ p. 1.
—— (67³) On some Cycadean Fruits from the Secondary rocks of
Britain. _Geol. Mag_. vol. +iv.+ p. 101.
—— (68) British Fossil Pandanaceae. _Ibid_. vol. +v.+ p. 153.
—— (69) On _Beania_, a new genus of Cycadean Fruit from the
Yorkshire Oolite. _Ibid_. vol. +vi.+ p. 1.
—— (69²) On some undescribed Coniferous fruits from the Secondary
rocks of Britain. _Ibid_. vol. +vi.+ p. 1.
—— (70) On Fossil Cycadean stems from the Secondary rocks of
Britain. _Trans. Linn. Soc_. vol. +xxvi.+ p. 675.
—— (71) On two undescribed Coniferous fruits from the Secondary
rocks of Britain. _Geol. Mag_. vol. +viii.+ p. 1.
—— (77) Description of a new species of _Araucarites_ from the
Coralline Oolite of Malton. _Quart. Journ. Geol. Soc_. vol.
+xxxiii.+ p. 402.
—— (93) On _Cycas Taiwaniana_, sp. nov. and _C. Seemanni_ R. Br.
_Journ. Bot_. vol. +xxxi.+ p. 1.
=Carter, M. Geraldine=. (11) A Reconsideration of the origin of
Transfusion-tissue. _Ann. Bot_. vol. +xxv.+ p. 975.
=Caspary, R.= and =R. Triebel=. (89) Einige fossile Hölzer Preussens.
_K. Preuss. Geol. Landesanstalt_, Bd. +ix.+ Heft iii. p. 113.
=Čelakovský, L.= (82) Zur Kritik der Ansichten von den Fruchtschuppe
der Abietineen. _Abh. K. böhm. Ges. Wiss. Prag_ [vi], Bd. +ii.+
=Chamberlain, C. J.= (06) The ovule and female gametophyte of _Dioon_.
_Bot. Gaz._ vol. +xlii.+ p. 321.
—— (09) _Dioon spinulosum. Ibid._ vol. +xlviii.+ p. 401.
—— (10) See Coulter and Chamberlain.
—— (10²) Fertilization and embryogeny in _Dioon edule_. _Bot. Gaz._
vol. +l.+ p. 415.
—— (11) The adult Cycad Trunk. _Ibid._ vol. +lii.+ p. 81.
—— (12) Morphology of _Ceratozamia_. _Ibid._ vol. +liii.+ p. 1.
—— (12²) A round-the-world Botanical Excursion. _Pop. Sci. Monthly_,
vol. +lxxxi.+ p. 417.
—— (12³) Two species of _Bowenia_. _Bot. Gaz._ vol. +liv.+ p. 419.
—— (13) _Macrozamia Moorei_, a connecting link between living and
fossil Cycads. _Bot. Gaz._ vol. +lv.+ p. 141.
=Chapman, F.= (09) Jurassic Plant-remains from Gippsland, Pt. ii. _Rec.
Geol. Surv. Victoria_, vol. +iii.+ pt. i. p. 103.
=Chrysler, M. A.= (15) The Medullary rays of _Cedrus_. _Bot. Gaz._ vol.
+lix.+ p. 387.
=Church, A. H.= (14) On the Floral Morphology of _Welwitschia
mirabilis_ (Hooker). _Phil. Trans. R. Soc._ vol. 205, p. 115.
=Cockerell, T. D. A.= (06) The Fossil Flora and Fauna of the Florissant
(Colorado) shales. _Univ. Colorado Series_, vol. +iii.+ No. 3.
—— (08) Description of Tertiary Plants. II. _Amer. Journ. Sci._ vol.
+xxvi+ [4], p. 537.
—— (08²). The Fossil Flora of Florissant, Colorado. _Bull. Amer.
Mus. Nat. Hist._ vol. +xxiv.+ p. 71.
—— (08³) Florissant; a Miocene Pompeii. _Pop. Sci. Monthly_ (Aug.
1908, p. 112).
=Coemans, E.= (66) Description de la flore fossile du premier étage du
terrain Crétacé du Hainaut. _Mém. Acad. R. Belg._, tome +xxxvi.+
=Coker, W. C.= (03) On the gametophyte and embryo of _Taxodium_. _Bot.
Gaz._ vol. +xxxvi.+ p. 1.
—— (09) Vitality of Pine seeds and the delayed opening of cones.
_Amer. Nat._ vol. +xliii.+ p. 677.
=Compter, G.= (94) Die fossile Flora des untern Keupers von
Ostthüringen. _Zeitsch. für Naturwiss._ _Leipzig_, Bd. +lxvii.+
p. 205.
—— (03) Cycadeenfrüchte aus der Lettenkohle von Apolda. _Zeitsch.
für Naturwiss._ _Stuttgart_, Bd. +lxxv.+ p. 171.
=Compton, R. H.= (08) See South and Compton.
=Cowentz, H.= (78) Ueber ein tertiares Vorkommen Cypressenartiger
Hölzer bei Calistoga in Californien. _Neues Jahrb. Min._ p. 800.
—— (82) Fossile Hölzer aus der Sammlung der König. geol.
Landesanstalt zu Berlin. _Jahrb. K. preuss. geol. Land. Bergakad.
Berlin für das Jahr_ 1881, p. 144.
—— (85) Sobre algunos arboles fosiles del Rio Negro. _Bol. Acad.
Nac. Cienc. Cordoba_, tom. +vii.+ p. 575.
—— (86) Die Angiospermen des Bernsteins. _Danzig._
—— (89) Ueber Thyllen und Thyllen-ähnliche Bildungen, vornehmlich im
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