by Beudant, "Mineralogie," ii., 178).
II. Green-sand from Kent, England. Dr. Edward Turner (cited by Rogers,
Final Report, Geol. N. Jersey, page 206).
III. Loganite from the Eozoon of Burgess.
IV. Green-sand, Lower Silurian; Red Bird, Minnesota.
V. Green-sand, Cretaceous, New Jersey.
VI. Green-sand, Lower Silurian, Orleans Island.
The last four analyses are by myself."
I. II. III. IV. V. VI.
Silica 40·0 48·5 35·14 46·58 50·70 50·7
Protoxyd of iron 24·7 22·0 8·60 20·61 22·50 8·6
Magnesia 16·6 3·8 31·47 1·27 2·16 3·7
Lime 3·3 2·49 1·11
Alumina 1·7 17·0 10·15 11·45 8·03 19·8
Potash traces 6·96 5·80 8·2
Soda ·98 ·75 ·5
Water 12·6 7·0 14·64 9·66 8·95 8·5
---- ---- ------ ----- ------ -----
98·9 98·3 100·00 100·00 100·00 100·0
An eminent example is the Silurian limestone of Pole Hill, in New
Brunswick, collected by the late Mr. Robb, of the Geological Survey,
and referred to in the text. I cannot doubt that the silicate injecting
Crinoids and other fossils in this limestone must have been introduced
into these when still recent, and the same remark applies to the
serpentine filling a coral at Lake Chebogamong, and fragments of
corals at Melbourne, in Eastern Canada, and to the similar mineral
filling fossils in a limestone from Llangwyllog, in Wales, and in that
of Maxville, Ohio. Hunt regarded all these as coming essentially into
the same category as regard to general composition and properties. His
analysis of the minerals from Pole Hill and Llangwyllog is as follows:--
Pole Hill. Llangwyllog.
Silica 38·93 35·32
Alumina 28·88 22·66
Protoxyd of iron 18·86 } 24·12 }
Magnesia 4·25 } 6·96 }
Potash 1·69 } 1·40 }
Soda ·48 } 0·67 }
Water 6·91 11·46
Insoluble, quartz
------ -----
100·00 99·89
These minerals approach in composition to the jollyte of Von Kobell,
from which they differ in containing a portion of alkalies, and only
one half as much water. In these respects they agree nearly with the
silicate found by Robert Hoffman, at Raspenau, in Bohemia, where it
occurs in thin layers alternating with picrosmine, and surrounding
masses of Eozoon in the Laurentian limestones of that region;[51]
the Eozoon itself being there injected with a hydrous silicate which
may be described as intermediate between glauconite and chlorite in
composition."
[Footnote 51: _Journ. fur Prakt. Chemie_, Bd., 106 (1869), p. 356.]
In the Welsh specimen the silicate is of a deep green colour, except
where oxidized, and though only 3 per cent, of the whole, is sufficient
to give it an olive colour and slight serpentinous lustre. In the Pole
Hill material, the silicate amounts to 5 per cent, of the whole, and
is of a greyish colour. For some further particulars, see my Paper on
"Fossils Mineralized with Silicates" (_Journal Geological Society_,
February, 1879).
* * * * *
C. Affinities of Eozoon, etc., with more Modern Forms.
Dr. Carpenter, who in admirable papers, which I need not quote
here,[52] has illustrated in detail the structures of Eozoon, and
shown its resemblance to modern forms, places Eozoon as a generalized
type between the Nummuline and Rotaline groups of Foraminifera. It
resembles the former in its fine and complicated tubulations, and some
of the larger sessile forms of the latter in its habit of growth.
More especially, this is near to that of the genera Carpenteria and
Polytrema. In the former, more especially, there are a number of
somewhat flattened calcareous cells with perforated walls, and built
up in a conical form around a central pipe or funnel into which the
apertures of the cells open. A specimen of Carpenteria, enlarged and
having the walls of its cells thickened by a supplemental tubulated
deposit like that of Calcarina, would approach very near to Eozoon.
[Footnote 52: I may specially refer to the following:--
W. B. Carpenter on _Eozoon Canadense_. _Intellectual Observer_, No.
xl., p. 300, 1865. Supplemental notes on the structure and affinities
of _Eozoon Canadense_, _Quart. Journ. Geol. Soc._, Lond. Vol. xxii.,
pp. 219-228, 1866. Notes on the structures and affinities of _Eozoon
Canadense_. _Canad. Nat._, new ser., vol. ii., pp. 111-119, wood-cut,
1865. A reprint from _Quart. Journ. Geol. Soc._, Lond., 1865. Further
observations on the structure and affinities of _Eozoon Canadense_.
In a letter to the President. _Proc. Roy. Soc._, Lond., vol, xxv.,
pp. 503-508, 1867. New observations on _Eozoon Canadense_. _Ann._ and
_Mag. Nat. Hist._, sen 4, vol. xiii., pp. 456-470, one plate, 1874.
Final note on _Eozoon Canadense_. _Ann._ and _Mag. Nat. Hist._, ser.
4, vol. xiv., pp. 371-372, 1874. Remarks on Mr. H. J. Carter's letter
to Prof. King on the structure of the so-called _Eozoon Canadense_.
_Ann._ and _Mag. Nat. Hist._, ser. 4, vol. xiii., pp. 277-284, with two
engravings, 1874.]
The question of the general relation of an organism like Eozoon to
creatures known to us in the modern seas may be answered in either of
two ways:--(1) Functionally or in relation to the position of such
an animal in nature: or (2) Zoologically, or with reference to its
affinities to other animals. With reference to the first consideration,
the answer is plain. The geological function of Eozoon was that of
a collector of calcareous matter from the surrounding waters, then
probably very rich in calcium carbonate, and its role was the same with
that of the Stromatoporæ and calcareous Sponges, smaller Foraminifera
and Corals in latter times. The answer to the second aspect of the
question is less easy. An ordinary observer would at once place
Eozoon with the Stromatoporidæ or Layer-corals, which fill or even
constitute whole beds of limestone in the Cambro-Silurian, Silurian
and Devonian Periods. While, however, Eozoon has been claimed on
the highest authority for the Rhizopods, the Stromatoporæ and their
allies have been regarded as Sponges, or more recently as Hydroids
allied to the Hydractiniæ and Millepores.[53] I confess that I am not
satisfied with these interpretations. I have in my collections large
numbers of encrusting spinous forms, usually called Stromatoporæ, but
which I have long set aside as probably Hydractiniæ. There are other
forms with large vertical tubes which I have regarded as corals,
but some Stromatoporæ seem to be different from either, and I am
still disposed to regard many of them as Protozoa. Bearing in mind,
however, that the Silurian is as remote from the Laurentian on the
one hand as from the Tertiary on the other, we might be prepared to
expect that if the Layer-corals of the Silurian are divisible into
different groups, somewhat widely separated, and we have in the lower
Palæozoic the peculiar type of Cryptozoon, we may be prepared to
expect in the Laurentian much more generalized forms, less susceptible
of classification in our modern systems. If, therefore, Eozoon were
accessible to us in a living state, I should not be surprised to find
that--while perhaps more akin to the calcareous-shelled Rhizopods than
to any other modern group--it may have presented points of resemblance
to Sponges or even to Hydroids, in its skeleton and mode of growth, and
even in the arrangement of its soft parts.
[Footnote 53: See Nicholson and Murie's able memoirs, Publications of
Pal. Soc, 1885.]
Taking this view of its nature and relations, the genus and the
Laurentian species may be characterized as follows:--
_Genus_ Eozoon, _Dawson_.
Foraminiferal skeletons, with irregular and often confluent cells,
arranged in concentric and horizontal laminæ, or sometimes piled in an
acervuline manner. Septal orifices irregularly disposed. Proper wall
finely tubulated. Intermediate skeleton with branching canals.
Eozoon Canadense, _Dawson_.
In inverted conical or rounded masses or thick encrusting sheets,
frequently of large dimensions. Typical structure stromatoporoid, or
with concentric calcareous walls, frequently uniting with each other,
and separating flat chambers, more or less mammillated, and spreading
into horizontal lobes and small chamberlets; chambers often confluent
and crossed by irregular calcareous pillars connecting the opposite
walls. Upper part often composed of acervuline chambers of rounded
forms. Proper wall tubulated very finely. Intermediate skeleton
largely developed, especially at the lower part, and traversed by large
branching canals, often with smaller canals in their interstices. Lower
laminæ and chambers often three millimetres in thickness. Upper laminæ
and chambers one millimetre or less. Age Upper Laurentian and perhaps
Huronian.
_Var._ minor.--Supplemental skeleton wanting, except near the base, and
with very fine canals. Laminæ of sarcode much mammillated, thin, and
separated by very thin walls. Probably a depauperated variety.
_Var._ acervulina.--In oval or rounded masses, wholly acervuline. Cells
rounded; intermediate skeleton absent or much reduced; cell-walls
tubulated. This may be a distinct species, but it closely resembles the
acervuline parts of the ordinary form.
Assuming the Archæospherinæ so abundantly found in the Eozoon
limestones to be distinct organisms, and not mere germs or buds of
Eozoon, they may be thus defined:--
_Genus_ Archæospherina, _Dawson_.
A provisional genus, to include rounded solitary chambers, or
globigerine assemblages of such chambers, with the cell-wall
surrounding them tubulated as in Eozoon, or perhaps in some cases with
simple pores like those of Rotalines. They may be distinct organisms,
or gemmæ, or detached fragments of Eozoon. Some of them much resemble
the bodies figured by Dr. Carpenter, as gemmæ or ova and primitive
chambers of Orbitolites. They are very abundant on some of the strata
surfaces of the limestones at Côte St. Pierre. Age Upper Laurentian.
I may add here the characters of Matthew's new genus, Archæozoon, as
given by him:--
_Genus_ Archæospherina, _Matthew_.
Skeleton composed of thin concentric laminæ convex upward, and having
between them a granular layer filled with minute branching canals.
Archæospherina Acadiense, Matthew.
Habit of growth cylindrical in masses or groups, budding upward. The
microscopic characters are thus given by Matthew[54]:--
"The structures appear to be allied more closely to Cryptozoon than to
Eozoon. The microscopic structure is most easily recognised in the
earthy (as distinguished from the calcareous) layers, and consists
of minute branching canals. Under a one-inch objective the smaller
canals have the appearance of minute threads, which run sometimes for a
distance of two millimetres without branching. The larger canals branch
more frequently and are more sinuous. The canals cross and anastomose
with each other; they run chiefly at right angles to the axis of the
fossil, and appear to branch most in going outward from the centre.
More rarely they ascend from the earthy to the calcareous layer,
branching upward."
[Footnote 54: Bulletin No. ix., Nat. Hist. Soc of New Brunswick, 1890.]
In limestone of the Upper Laurentian, near St. John, New Brunswick.
* * * * *
D. Cryptozoon.
The description above given of Archæozoon very naturally leads us to
consider the allied Cambrian and pre-Cambrian forms known as Cryptozoon.
This remarkable and problematical type was first described by Prof.
James Hall in the Appendix to his Annual Report of 1882 (No. 26). It
is a large massive organism, occurring abundantly on the surface of a
limestone of Calciferous (Upper Cambrian) age at Greenfield, Saratoga
County, New York. The individuals sometimes attain a diameter of two
feet, and are often surrounded by smaller specimens apparently budding
off from them. Like Stromatoporæ, they consist of concentric laminæ,
but these are concave upward, giving a bowl-shaped form to the summits
of the individuals. Prof Hall describes them as "made up of irregular
concentric laminæ of greater or less density, and of very unequal
thickness. The substance between the concentric lines in well-preserved
specimens is traversed by numerous minute irregular canaliculi which
branch and anastomose without regularity. The central portion of
the masses is usually filled with crystalline granular and Oolitic
material, and many specimens show the intrusion of these extraneous and
inorganic substances between the laminæ."
Professor Hall having kindly presented some good specimens to the Peter
Redpath Museum, I have had sections made, and have thus been able to
verify his description, and to compare the structures with those of
some of the more ancient Stromatoporoid specimens in our collections,
including the Archæozoon from New Brunswick, of which Mr. Matthew
has presented a fine slab to the Museum. I have also, through the
kindness of Professor Winchell, been enabled to compare these with his
_Cryptozoon Minnesotense_, and Dr. Walcott has added specimens of his
Stromatoporoid forms from the pre-Cambrian beds of Arizona. It would
appear from these and other specimens in our collections from the
Cambrian and older Ordovician beds, that we have here an ancient type
of Stromatoporoid organism in which the original laminæ seem to have
been thin and coriaceous, without apparent pores or pillars connecting
them with each other, but having between them relatively-thick layers
of fine fragmental matter penetrated by numerous irregularly tortuous
and branching tubes. The laminæ often present a carbonaceous or
chitinous appearance, though frequently replaced by mineral matter,
and the intervening layers show both a calcareous and carbonaceous
substance, with much fine silicious sand often as rounded grains,
and apparently some dolomitic granules. The tubules seem destitute
of any distinct wall, otherwise the whole would resemble on a large
scale the nodular and laminated masses of _Girvanella_, which Wethered
has described as surrounding organic fragments in Silurian and
Carboniferous and Jurassic limestones in England.[55]
[Footnote 55: British Association, Liverpool meeting, 1896.]
The _Streptochetus_ of Seely from the Chazy limestone[56] is evidently
very near to Girvanella, if not generically identical, and I have a
similar species from the Lower Cambrian pebbles in the conglomerates
of the Quebec group. In all these forms, however, the thicker or
intermediate laminæ seem to consist wholly of definite convoluted
tubes, whereas in Cryptozoon the tubes, or tubular perforations, are
separated by a mass of material which in the best preserved specimens
seems to consist of a fibrous stroma including calcareous and silicious
particles. It seems doubtful to what class of beings such a structure
should be referred; but whatever its nature, it evidently had great
powers of growth, and seems to be a very ancient form of life.
[Footnote 56: _Amer. Journ. of Science_, 1885. See Nicholson, "Manual
of Palæontology," ed. of 1889.]
One of the species similar in structure to Hall's type, but budding
out into turbinate branches, was discovered by Mr. E. T. Chambers, of
Montreal, in the Ordovician limestone of Lake St. John, and has been
named _C. boreale_. It differs in structure from Hall's species in
having the tubes less tortuous and more nearly parallel to the laminæ.
In its outline it reminds one of the problematical Eozoon from the
Hastings group at Tudor, Ontario, referred to in the text.
Should time permit, I hope to have all the specimens in our collections
illustrating this interesting and primitive type examined and
described. In the meantime I may merely remark that a near modern
analogue would seem to be the gigantic arenaceous Foraminifer _Neusina
Agassizi_, Goës, dredged by Alexander Agassiz in the Pacific, and
described in the Bulletin of the Museum of Comparative Zoology (Vol.
xxiii., No. 5, 1892). The modern form, it is true, is flat and
foliaceous; but some of the old species approach to this shape, and
if we suppose the little cells of Neusina to represent the tubes of
Cryptozoon, and the carbonaceous matter of the latter to be the remains
of the chitinous stroma seen in some specimens, the general resemblance
will be very close.
The whole subject of these peculiar Stromatoporoid forms extending
from the Upper Cambrian to the Laurentian, deserves a full and careful
investigation, for which I am endeavouring to collect material.
* * * * *
E. Receptaculites and Archæocyathus.
In "The Dawn of Life" (1875), reference was made to the singular and
complicated organisms of the Upper Cambrian and Ordovician systems
known as Receptaculites, which at that time was generally regarded as
foraminiferal, and is still placed by Zittel, in his great work on
Palæontology, among forms doubtfully referable to that group. It has
also been referred to Sponges, though on very uncertain grounds. It has
not, however, so far as I am informed, been traced any farther back
than the Upper Cambrian (Calciferous), and no structural links are
known to connect it with either Eozoon or Archæozoon. For this reason
it was omitted in the text; but I think it well to mention it here, and
to direct attention to it as possibly one of the complex Protozoa which
may be traced far back toward the beginnings of life.[57]
[Footnote 57: Billings, "Palæozoic Times."]
Another primitive and generalized genus mentioned in the text is
_Archæocyathus_ of Billings, whose headquarters seem to be in the Lower
Cambrian, and which may probably be traced farther back.
Mr. Billings described the genus in his "Report on Canadian Fossils"
(1861-64), taking _A. profundus_, from the Lower Cambrian of L'Anse à
Loup, on the Labrador coast, in the first instance, as the type.
A few years later, my attention was attracted to this species by
specimens presented to me by Mr. Carpenter, a missionary on the
Labrador coast, and which Mr. Billings kindly permitted me to compare
with his specimens in the Museum of the Geological Survey, collected
by the late Mr. Richardson, at L'Anse à Loup, in Labrador, in what
were then called Lower Potsdam rocks. Slices of the specimens were
made for the microscope, when it appeared that, though they had
the general aspect of turbinate corals, like Petraia, etc., they
were quite dissimilar in structure, more especially in their porous
outer and inner walls and septa (see Fig. 5, p. 35). Yet they could
scarcely be referred to the group of porous corals known in much later
formations and in the modern seas. Nor could they be referred with
much probability to Sponges, as they were composed of solid calcareous
plates, which, as was evident from their textures, could not have been
originally spicular. One seemed thus shut up to the conclusion that
their nearest alliance was with Foraminifera, and if so, they were
very large and complex forms of that group, consisting of perforated
chambers arranged around a central cavity. I accordingly mentioned them
in this connection in 1875, not as closely related to Eozoon, but as
apparently showing the existence of very complex foraminiferal forms in
the Lower Cambrian.
The specimens thus noticed were altogether calcareous, and were of
the species named _A. profundus_ by Mr. Billings. He had, however,
referred to the same genus silicified specimens from a later formation,
the Calciferous (Upper Cambrian) at Mingan, under the name _A.
Minganensis_, which were subsequently found to be associated with
spicules resembling those of lithistid sponges, and which proved to
be very different from the Lower Cambrian form, and are now referred
to a different genus. The subject had thus become involved in some
confusion, and was left in this state by Mr. Billings on his death.
I therefore asked my friend, Dr. Hinde, of London, to re-examine my
specimens, and at the same time those of the Geological Survey were
placed in his hands by Mr. Whiteaves. Hinde also obtained specimens
from Lower Cambrian rocks in Sardinia, where they seem to be abundant,
and from Spain. He states the results of his examinations very fully
in a paper in the Journal of the _Geological Society of London_.[58] He
retains the original name for the older and calcareous form from L'Anse
à Loup, separating from it, however, another form, _A. Atlanticus_
of Billings's, which is destitute of distinct radiating septa and
acervuline, like the lower part of _A. profundus_. This he names
_Spirocyathus_. The Mingan species he places with Sponges under the
generic name, _Archæoscyphia_. In this Walcott substantially agrees
with Hinde in his "Memoir on the Lower Cambrian Fauna." Both seem to
refer Archæocyathus to corals, though admitting its very exceptional
and anomalous structure. I think, however, we may still be allowed to
entertain some doubts as to the reference to corals, more especially
as the skeleton does not seem to have consisted of aragonite, but of
ordinary calcite, like that of the Foraminifera. It is in any case a
primitive form which seems to be dying out in the Lower Cambrian, and
we may hope that it may be traced into the pre-Cambrian, and may form a
link connecting the Palæozoic with the Eozoic faunas. In my description
of it in "The Dawn of Life" in 1875, I used the following terms:--"To
understand Archæocyathus, let us imagine an inverted cone of carbonate
of lime from an inch or two to a foot in length, with its point planted
in the mud in the bottom of the sea, while its open cup extends upward
into the clear water. The lower part buried in the bottom is composed
of an irregular network of thick calcareous plates, enclosing chambers
communicating with one another. Above this, where the cup expands, its
walls are made up of inner and outer plates, perforated with numerous
round pores in vertical rows, and connected with each other by vertical
partitions also perforated, so as to establish a free communication
of the enclosed radiating chambers with each other, as well as with
the water within and without. Such a structure might no doubt serve as
a skeleton for a coral of somewhat peculiar internal structure, but
it might just as well accommodate a protozoan with chambers for its
sarcode, and pores for emission of pseudopods, both outwardly and by
means of the interior cup, which in that case would represent a funnel
like that of Carpenteria, or one of the tubes of Eozoon."
[Footnote 58: Vol. xlv., 1889, pp. 125 _et seq._]
On the whole, when we consider the magnitude and synthetic character
of such forms as Cryptozoon, Receptaculites, and Archæocyathus,
and their association with generalized types of Crustaceans and
Brachiopods, we can scarcely fail to perceive that at the base of the
Palæozoic we are leaving the reign of the higher marine invertebrates,
and entering on a domain where lower and probably Protozoan forms must
be dominant, and so are getting at least within calculable distance of
the beginnings of life.
* * * * *
F. Pre-Geological Evolution.
Reference is incidentally made in the text to the doctrine implied in
the old notion of successive cataclysms and renewals of the earth,
held by some ancient mythologies and philosophies, and revived in a
slightly different form by Mr. Herbert Spencer, in connection with the
requirements of the Darwinian evolution by natural selection. This
primitive idea was illustrated at considerable length by Professor
Poulton in his address as President of the Zoological Section of the
British Association at its meeting in Liverpool (September, 1896). In
this new and ably presented form, it deserves some notice as excluding
the hope of our finding the beginnings of life in any geological
formations at present known.