~Cambridge Natural Science Manuals.~
=BIOLOGICAL SERIES.=
GENERAL EDITOR:—ARTHUR E. SHIPLEY, M.A.
FELLOW AND TUTOR OF CHRIST’S COLLEGE, CAMBRIDGE.
FOSSIL PLANTS.
~London~: C. J. CLAY AND SONS,
CAMBRIDGE UNIVERSITY PRESS WAREHOUSE,
AVE MARIA LANE,
AND
H. K. LEWIS,
136, GOWER STREET, W.C.
[Illustration]
~Glasgow~: 263, ARGYLE STREET.
~Leipzig~: F. A. BROCKHAUS.
~New York~: THE MACMILLAN COMPANY.
~Bombay~: E. SEYMOUR HALE.
[Illustration: TREE STUMPS IN A CARBONIFEROUS FOREST. VICTORIA PARK,
GLASGOW.]
FOSSIL PLANTS
FOR STUDENTS OF BOTANY AND GEOLOGY
BY
A. C. SEWARD, M.A., F.G.S.
ST JOHN’S COLLEGE, CAMBRIDGE,
LECTURER IN BOTANY IN THE UNIVERSITY OF CAMBRIDGE.
WITH ILLUSTRATIONS.
VOL. I.
CAMBRIDGE:
AT THE UNIVERSITY PRESS.
1898
[_All Rights reserved._]
~Cambridge~:
PRINTED BY J. AND C. F. CLAY,
AT THE UNIVERSITY PRESS.
PREFACE.
In acceding to Mr Shipley’s request to write a book on Fossil Plants
for the Cambridge Natural History Series, I am well aware that I have
undertaken a work which was considered too serious a task by one who
has been called a “founder of modern Palaeobotany.” I owe more than I
am able to express to the friendship and guidance of the late Professor
Williamson; and that I have attempted a work to which he consistently
refused to commit himself, requires a word of explanation. My excuse
must be that I have endeavoured to write a book which may render more
accessible to students some of the important facts of Palaeobotany, and
suggest lines of investigation in a subject which Williamson had so
thoroughly at heart.
The subject of Palaeobotany does not readily lend itself to adequate
treatment in a work intended for both geological and botanical
students. The Botanist and Geologist are not always acquainted
with each other’s subject in a sufficient degree to appreciate the
significance of Palaeobotany in its several points of contact with
Geology and recent Botany. I have endeavoured to bear in mind the
possibility that the following pages may be read by both non-geological
and non-botanical students. It needs but a slight acquaintance with
Geology for a Botanist to estimate the value of the most important
applications of Palaeobotany; on the other hand, the bearing of fossil
plants on the problems of phylogeny and descent cannot be adequately
understood without a fairly intimate knowledge of recent Botany.
The student of elementary geology is not as a rule required to concern
himself with vegetable palaeontology, beyond a general acquaintance
with such facts as are to be found in geological text-books. The
advanced student will necessarily find in these pages much with which
he is already familiar; but this is to some extent unavoidable in a
book which is written with the dual object of appealing to Botanists
and Geologists. While considering those who may wish to extend their
botanical or geological knowledge by an acquaintance with Palaeobotany,
my aim has been to keep in view the requirements of the student who
may be induced to approach the subject from the standpoint of an
original investigator. As a possible assistance to those undertaking
research in this promising field of work, I have given more references
than may seem appropriate to an introductory treatise, and there are
certain questions dealt with in greater detail than an elementary
treatment of the subject requires. In several instances references
are given in the text or in footnotes to specimens of Coal-Measure
plants in the Williamson cabinet of microscopic sections. Now that this
invaluable collection of slides has been acquired by the Trustees of
the British Museum, the student of Palaeobotany has the opportunity of
investigating for himself the histology of Palaeozoic plants.
My plan has been to deal in some detail with certain selected types,
and to refer briefly to such others as should be studied by anyone
desirous of pursuing the subject more thoroughly, rather than to cover
a wide range or to attempt to make the list of types complete. Of late
years there has been a much wider interest evinced by Botanists in
the study of fossil plants, and this is in great measure due to the
valuable and able work of Graf zu Solms-Laubach. His _Einleitung in
die Palaeophytologie_ must long remain a constant book of reference
for those engaged in palaeobotanical work. While referring to authors
who have advanced the study of petrified plants of the Coal period,
one should not forget the valuable services that have been rendered by
such men as Butterworth, Binns, Wilde, Earnshaw, Spencer, Nield, Lomax
and Hemingway, by whose skill the specimens described by Williamson and
others were first obtained and prepared for microscopical examination.
I am indebted to many friends, both British and Continental, for help
of various kinds. I would in the first place express my thanks to
Professor T. McKenny Hughes for having originally persuaded me to begin
the study of recent and fossil plants. I am indebted to Prof. Nathorst
of Stockholm, Dr Hartz of Copenhagen, Prof. Zeiller, Dr Renault and
Prof. Munier-Chalmas of Paris, Prof. Bertrand of Lille, Prof. Stenzel
and the late Prof. Roemer of Breslau, Dr Sterzel of Chemnitz, the
late Prof. Weiss of Berlin, the late Dr Stur of Vienna, and other
continental workers, as well as to Mr Knowlton of Washington, for
facilities afforded me in the examination of fossil plant collections.
My thanks are due to the members of the Geological and Botanical
departments of the British Museum; also to Mr E. T. Newton of the
Geological Survey, and to those in charge of various provincial
museums, for their never-failing kindness in offering me every
assistance in the investigation of fossil plants under their charge.
Prof. Marshall Ward has given me the benefit of his criticism on the
section dealing with Fungi; and my friend Mr Alfred Harker has rendered
me a similar service as regards the chapter on Geological History. I
am especially grateful to my colleague, Mr Francis Darwin, for having
read through the whole of the proofs of this volume. To Mr Shipley, as
Editor, I am under a debt of obligation for suggestions and help in
various forms. I would also express my sense of the unfailing courtesy
and skill of the staff of the University Press.
My friend Mr Kidston of Stirling has always generously responded to my
requests for the loan of specimens from his private collection. Prof.
Bayley Balfour of Edinburgh, Mr Wethered of Cheltenham and others have
assisted me in a similar manner. I would also express my gratitude
to Dr Hoyle of Manchester, Mr Platnauer of York, and Mr Rowntree of
Scarborough for the loan of specimens.
To Dr Henry Woodward of the British Museum I am indebted for the loan
of the woodblocks made use of in figs. 10, 47, 60, 66, and 101, and to
Messrs Macmillan for the process-block of fig. 25.
For the photographs reproduced in figs. 15, 34, 68, 102 and 103 I owe
an acknowledgment to Mr Edwin Wilson of Cambridge, and to my friend Mr
C. A. Barber for the micro-photograph made use of in fig. 40.
In conclusion I wish more particularly to thank my wife, who has drawn
by far the greater number of the illustrations, and has in many other
ways assisted me in the preparation of this Volume.
In Volume II the Systematic treatment of Plants will be concluded,
and the last chapters will be devoted to such subjects as geological
floras, plants as rock-builders, fossil plants and evolution, and other
general questions connected with Palaeobotany.
A. C. SEWARD.
BOTANICAL LABORATORY, CAMBRIDGE.
_March_, 1898.
TABLE OF CONTENTS.
PART I. GENERAL.
CHAPTER I.
=HISTORICAL SKETCH.= Pp. 1–11.
Fossil plants and the Flood. Sternberg and Brongniart. The
internal structure of fossil plants. English Palaeobotanists.
Difficulties of identification.
CHAPTER II.
=RELATION OF PALAEOBOTANY TO BOTANY AND GEOLOGY.= Pp. 12–21.
Neglect of fossils by Botanists. Fossil plants and distribution.
Fossil plants and climate. Fossil plants and phylogeny.
CHAPTER III.
=GEOLOGICAL HISTORY.= Pp. 22–53.
Rock-building. Calcareous rocks. Geological sections. Inversion of
strata. Table of Strata:
I. Archaean, 34–36. II. Cambrian, 36–37. III. Ordovician, 37–38.
IV. Silurian, 38. V. Devonian, 39. VI. Carboniferous, 39–45.
VII. Permian, 45–47. VIII. Trias., 47–48. IX. Jurassic, 48–49. X.
Cretaceous, 50–51. XI. Tertiary, 51–53. Geological Evolution.
CHAPTER IV.
=THE PRESERVATION OF PLANTS AS FOSSILS.= Pp. 54–92.
Old surface-soils. Fossil wood. Conditions of fossilisation.
Drifting of trees. Meaning of the term ‘Fossil.’ Incrustations.
Casts of trees. Fossil casts. Plants and coal. Fossils in
half-relief. Petrified trees. Petrified wood. Preservation of
tissues. Coal-balls. Fossil nuclei. Fossil plants in volcanic
ash. Conditions of preservation.
CHAPTER V.
=DIFFICULTIES AND SOURCES OF ERROR IN THE
DETERMINATION OF FOSSIL PLANTS.= Pp. 93–109.
External resemblance. Venation characters. Decorticated stems.
Imperfect casts. Mineral deposits simulating plants. Traces of
wood-borers in petrified tissue. Photography and illustration.
CHAPTER VI.
=NOMENCLATURE.= Pp. 110–115.
Rules for nomenclature. The rule of priority. Terminology and
convenience.
PART II. SYSTEMATIC.
CHAPTER VII.
=THALLOPHYTA.= Pp. 116–228.
=PAGE=
I. =PERIDINIALES= 117–118
II. =COCCOSPHERES AND RHABDOSPHERES= 118–121
III. =SCHIZOPHYTA= 121–138
A. SCHIZOPHYCEAE (CYANOPHYCEAE) 122–132
_Girvanella_ 124–126. Borings in shells 127–129.
_Zonatrichites_ 129–130.
B. SCHIZOMYCETES (BACTERIA) 132–138
_Bacillus Permicus_ 135–136. _B. Tieghemi_ and
_Micrococcus Guignardi_ 136. Fossil Bacteria 137–138.
IV. =ALGAE= 138–205
Scarcity of fossil algae. Fossils simulating Algae.
Recognition of fossil algae. _Algites &c._
A. DIATOMACEAE 150–156
Recent Diatoms. Fossil Diatoms. _Bactryllium &c._
B. CHLOROPHYCEAE 156–178
_a._ SIPHONEAE 157–177
α. =Caulerpaceae= 157–159
β. =Codiaceae= 159–164
_Codium_ 159–160. _Sphaerocodium_ 160.
_Penicillus_ 161. _Ovulites_ 161–164.
_Halimeda_ 164.
γ. =Dasycladaceae= 164–177
_Acetabularia_ 165–166. _Acicularia_ 166–169.
_Cymopolia_ 169–171. _Vermiporella_ 172–173.
_Sycidium_ 173. _Diplopora_ 174–175.
_Gyroporella_ 175. _Dactylopora_, Palaeozoic
and Mesozoic Siphoneae 175–177.
_b._ CONFERVOIDEAE 177–178
C.INCERTAE SEDIS 178–183
Boghead ‘Coal.’ _Reinschia_ 180–181. _Pila_ 181–182.
D. RHODOPHYCEAE 183–190
CORALLINACEAE 183–190
_Lithothamnion_ 185–189. _Solenopora_ 189–190.
E. PHAEOPHYCEAE 191–202
_Nematophycus_ 192–202
_Pachytheca_ 202–204
_Algites_ 204–205
V. =MYXOMYCETES (MYCETOZOA)= 205–206
_Myxomycetes Mangini_ 206.
VI. =FUNGI= 207–222
ASCOMYCETES. BASIDIOMYCETES.
Pathology of fossil tissues. _Oochytrium Lepidodendri_
216–217. _Peronosporites antiquarius_ 217–220.
_Cladosporites bipartitus_ 220. _Haplographites
cateniger_ 220. _Zygosporites_ 220–221. _Polyporus
vaporarius_ 221.
VII. =CHAROPHYTA= 222–228
CHAREAE 223–228
_Chara_ 225–228. _C. Bleicheri_ 226. _C. Knowltoni_
226–227. _C. Wrighti_ 227.
CHAPTER VIII.
=BRYOPHYTA.= Pp. 229–241.
I. =HEPATICAE= 230–236
_Marchantites_ 233–235. _M. Sezannensis_ 234–235.
II. =MUSCI= 236–241
_Muscites_ 238–241. _M. polytrichaceus_ 239–240.
Palaeozoic Mosses. _Muscites ferrugineus_ 241.
CHAPTER IX.
=PTERIDOPHYTA (VASCULAR CRYPTOGRAMS).= Pp. 242–294.
I. =EQUISETALES (RECENT)= 244–254
EQUISETACEAE 244–254
_Equisetum_ 246–254.
II. =FOSSIL EQUISETALES= 254–294
A. EQUISETITES 257–281
_Equisetites Hemingwayi_ 263–264. _E.
spatulatus_ 264–266. _E. zeaeformis_ 266. _E.
arenaceus_ 268–269. _E. columnaris_ 269–270.
_E. Beani_ 270–275. _E. lateralis_ 275–279. _E.
Burchardti_ 279–280.
B. PHYLLOTHECA 281–291
_Phyllotheca deliquescens_ 283–284. _P.
Brongniarti_ 286–287. _P. indica_ and _P.
australis_ 287–289.
C. SCHIZONEURA 291–294
_S. gondwanensis_ 292–293.
CHAPTER X.
=EQUISETALES (_continued_).= Pp. 295–388.
D. CALAMITES 295–383
I. =Historical sketch= 295–302
II. =Description of the anatomy of Calamites= 302–364
_a._ _Stems_ 304–329
_Arthropitys_, _Arthrodendron_, and
_Calamodendron_.
_b._ _Leaves_ 329–342
α. _Calamocladus_ (_Asterophyllites_) 332–336.
_C. equisetiformis_ 335–336.
β. _Annularia_ 336–342. _A. stellata_ 338–340.
_A. sphenophylloides_ 341–342.
_c._ _Roots_ 342–349
_d._ _Cones_ 349–365
_Calamostachys Binneyana_ 351–355. _C. Casheana_
355–357. _Palaeostachya vera_ 358–360.
_Calamostachys_, _Palaeostachya_ and
_Macrostachya_ 361–364.
III. =Pith-casts of Calamites= 365–380
_Calamitina_ 367–374. _Calamites_ (_Calamitina_)
_Göpperti_ 372–374. _Stylocalamites_ 374–376. _C._
(_Stylocalamites_) _Suckowi_ 374–376. _Eucalamites_
376–379. _C._ (_Eucalamites_) _cruciatus_ 378–379.
IV. =Conclusion= 381–383
E. ARCHAEOCALAMITES 383–388
_A. scrobiculatus_ 386–387.
CHAPTER XI.
SPHENOPHYLLALES. Pp. 389–414.
I. =SPHENOPHYLLUM= 389–414
A. =The anatomy of Sphenophyllum= 392–406
_a._ _Stems_ 392–398
_Sphenophyllum insigne_ and _S. plurifoliatum_
397–398.
_b._ _Roots_ 399
_c._ _Leaves_ 399
_d._ _Cones_ 401–406
_Sphenophyllostachys Dawsoni_ 402–405. _S.
Römeri_ 405–406.
B. =Types of vegetative Branches of Sphenophyllum= 407–412
_Sphenophyllum emarginatum_ 407–408. _S.
trichomatosum_ 408–409. _S. Thoni_ 410–411. _S.
speciosum_ 411–412.
C. =Affinities, Range and Habit of Sphenophyllum= 412–414
LIST OF ILLUSTRATIONS.
FRONTISPIECE. TREE STUMPS IN A CARBONIFEROUS FOREST. Drawn from a
photograph. (M. Seward.) PAGE 57.
FIG. PAGE
1. _Lepidodendron._ (M. S.) 10
2. Geological section 29
3. Table of strata 32, 33
4. Geological section (coal seam) 44
5. _Neuropteris Scheuchzeri_ Hoffm. (M. S.) 45
6. Submerged Forest at Leasowe. (M. S.) 59
7. Ammonite on coniferous wood. (M. S.) 61
8. Coniferous wood in flint. (M. S.) 62
9. Bored fossil wood. (M. S.) 62
10. Section of an old pool filled up with a mass of _Chara_. (From
block lent by Dr Woodward) 69
11. _Equisetites columnaris_ Brongn. (M. S.) 72
12. _Stigmaria ficoides_ Brongn. (M. S.) 73
13. _Cordaites etc._ in coal. (M. S.) 76
14. Crystallisation in petrified tissues 81
15. _Lepidodendron._ (From a photograph by Mr Edwin Wilson
of a specimen lent by Mr Kidston) 82
16. Cast of a fossil cell. (M. S.) 84
17. Calcareous nodule from the Coal-Measures 85
18. _Lepidodendron_ from Arran. (M. S.) 89
19. _Trigonocarpon_ seeds in a block of sandstone. (M. S.) 91
20. _Restio_, _Equisetum_, _Casuarina_ and _Ephedra_. (M. S.) 95
21. _Polygonum equisetiforme_ Sibth. and Sm. (M. S.) 96
22. _Kaulfussia æsculifolia_ Blume. (M. S.) 97
23. A branched Lepidodendroid stem (_Knorria mirabilis_ Ren.
and Zeill.). (M. S.) 102
24. Partially disorganised petrified tissue 107
25. Coccospheres and Rhabdospheres. (Lent by Messrs Macmillan) 119
26. _Girvanella problematica_ Eth. and Nich. (M. S.) 124
27. Fish-scale and shell perforated by a boring organism. (M. S.) 128
28. _Bacillus Tieghemi_ Ren. and _Micrococcus Guignardi_ Ren.
(M. S.) 135
29. _Laminaria_ sp. 140
30. Rill-mark; trail of a seaweed; tracks of a Polychaet. (M. S.) 143
31. _Chondrites verisimilis_ Salt. (M. S.) 146
32. _Lithothamnion mamillosum_ Gümb.; _Sycidium melo_ Sandb.;
_Bactryllium deplanatum_ Heer; Calcareous pebble from a
lake in Michigan. (M. S.) 155
33. _Cymopolia barbata_ (L.); _Acicularia Andrussowi_ Solms;
_Acicularia_ sp.; _A. Schencki_ (Möb.); _A. Mediterranea_
Lamx.; _Ovulites margaritula_ Lamx.; _Penicillus
pyramidalis_ (Lamx.) (M. S.) 162
34. _Acetabularia mediterranea_ Lamx. (Photograph by Mr Edwin
Wilson) 165
35. _Diplopora_; _Gyroporella_; _Penicillus_; _Ovulites
margaritula_ Lam.; _Confervites chantransioides_ (Born.) 174
36. Torbanite; _Pila bibractensis_ and _Reinschia australis_ 180
37. _Lithothamnion_ sp.; _L. suganum_ Roth.; _Sphaerocodium
Bornemanni_ Roth. 186
38. _Solenopora compacta_ (Billings). (M. S.) 189
39. _Nematophycus Logani_ (Daws.) 196
40. _Nematophycus Storriei_ Barb. (Photograph by Mr C. A. Barber) 199
41. Cells of _Cycadeoidea gigantea_ Sew., _Osmundites Dowkeri_
Carr and _Memecylon_ with vacuolated contents;
_Peronosporites antiquarius_ Smith; _Zygosporites_ 214
42. Tracheids of coniferous wood attacked by _Trametes
radiciperda_ Hart and _Agaricus melleus_ Vahl. 215
43. _Oochytrium Lepidodendri_ Ren.; _Polyporus vaporarius_ Fr.
var. _succinea_; _Cladosporites bipartitus_ Fel.;
_Haplographites cateniger_ Fel. (M. S.) 217
44. Cells of fossil plants with fungal hyphae 219
45. _Chara Knowltoni_ Sew.; _Chara foetida_ A. Br. (_A_ and _B_,
Mr Highley; _C–E_, M. S.) 224
46. _Chara Bleicheri_ Sap.; _Chara_? sp.; _C. Wrighti_ Forbes.
(M. S.) 226
47. _Chara Knowltoni_ Sew. (From block lent by Dr Woodward) 227
48. _Tristichia hypnoides_ Spreng.; _Podocarpus cupressina_ Br.
and Ben.; _Selaginella Oregana_ Eat. (M. S.) 231
49. _Marchantites erectus_ (Leck.) (M. S.) 233
50. _Marchantites Sezannensis_ Sap. (M. S.) 235
51. _Muscites polytrichaceus_ Ren. and Zeill. (M. S.) 239
52. _Equisetum maximum_ Lam.; _E. arvense_ L. 246
53. _Equisetum palustre_ L. (M. S.) 247
54. Plan of the vascular bundles in an _Equisetum_ stem; _E.
arvense_ L. 250
55. _Equisetum variegatum_ Schl.; _E. maximum_ Lam. 252
56. Calamitean leaf-sheath. (M. S.) 260
57. _Equisetites Hemingwayi_ Kidst. (Mr Highley) 262
58. _Equisetites spatulatus_ Zeill.; _E. zeaeformis_ (Schloth.);
_Equisetites lateralis_ Phill.; _Equisetites columnaris_
Brongn.; _Equisetum trachyodon_ A. Br. (M. S.) 265
59. _Equisetites platyodon_ Brongn. (M. S.) 267
60. _Equisetites Beani_ (Bunb.). (From a block lent by Dr
Woodward) 271
61. _Equisetites Beani_ (Bunb.). (M. S.) 272
62. _E. Beani_ (Bunb.). (M. S.) 274
63. _E. lateralis_ Phill. (M. S.) 275
64. _E. lateralis_ Phill. (M. S.) 278
65. _E. Burchardti_ Dunk. (M. S.) 279
66. _E. Yokoyamae_ Sew. (From a block lent by Dr Woodward) 280
67. _Phyllotheca_? sp. (From a photograph by Mr Edwin Wilson) 285
68. _Phyllotheca Brongniarti_ Zigno; _P. indica_ Bunb.;
_Calamocladus frondosus_ Grand’Eury. (M. S.) 287
69. _Schizoneura gondwanensis_ Feist. (M. S.) 293
70. Transverse section of a Calamite stem. (M. S.) 299
71. Transverse section of a young Calamite stem 305
72. Longitudinal and transverse sections of _Calamites_ 308
73. Transverse section of a Calamite stem 310
74. Transverse section of _Calamites_ (_Arthropitys_) sp. 312
75. Longitudinal section (tangential) of _Calamites_
(_Arthropitys_) sp. 313
76. Longitudinal section (tangential) of _Calamites_
(_Arthropitys_) sp. 314
77. Portion of a Calamite stem; partially restored. (M. S.) 316
78.╮ Transverse and longitudinal (radial) sections of a thick 318
79.╯ Calamite stem. (Mr Highley) 319
80. Transverse section of a Calamite showing callus wood 320
81. Longitudinal section of a young Calamite 321
82. Pith-casts of _Calamites_ (_Stylocalamites_) sp. (M. S.) 323
83. _Calamites_ (_Arthrodendron_) sp. Transverse and longitudinal
sections 327
84. Transverse section of _Calamites_ (_Calamodendron_)
_intermedius_ Ren. 328
85. Leaves of a Calamite. (M. S.) 330
86. Transverse section of a Calamite leaf 331
87. _Calamocladus equisetiformis_ (Schloth.) (Miss G. M.
Woodward) 334
88. _Annularia stellata_ (Schloth.) (M. S.) 339
89. _Annularia sphenophylloides_ Zenk. (M. S.) 340
90. Pith-cast of a Calamite, with roots. (M. S.) 343
91. Transverse sections of Calamite roots 345
92. Root given off from a Calamite stem 347
93. _Calamostachys_ sp. (M. S.) 350
94. _C. Binneyana_ (Carr.). (Mr Highley) 352
95. _C. Binneyana_ (Carr.) 354
96. _C. Casheana_ Will. 356
97. _Palaeostachya pedunculata_ Will. (M. S.) 357
98. _P. vera_ sp. nov. 359
99. _Calamites_ (_Calamitina_) Göpp. (Ett.) (M. S.) 368
100. _Calamites_ (_Calamitina_) _approximatus_ Brongn. From a
photograph by Mr Kidston 370
101. _Calamites_ (_Calamitina_) sp. (From a block lent by Dr
Woodward) 373
102. _Calamites_ (_Eucalamites_) _cruciatus_ Sternb. (From a
photograph by Mr Edwin Wilson) 377
103. _Archaeocalamites scrobiculatus_ (Schloth.). (From a
photograph by Mr Edwin Wilson) 385
104. Diagrammatic longitudinal section of _Sphenophyllum_ 393
105. Transverse and longitudinal sections of _Sphenophyllum
insigne_ (Will.) and _S. plurifoliatum_ Will. and Scott 394
106. _Sphenophyllum plurifoliatum_ Will. and Scott. (From a
photograph by Mr Highley) 398
107. _Sphenophyllum_ strobilus, stem and root 400
108. Diagrammatic longitudinal section of a _Sphenophyllum_
strobilus. (M. S.) 402
109. _Sphenophyllum emarginatum_ (Brongn.) (M. S.) 407
110. _Sphenophyllum Thoni_ Mahr.; _S. trichomatosum_ Stur.
(M. S.) 410
111. _Sphenophyllum speciosum_ (Royle). (M. S.) 411
=Note.= The references in the footnotes require a word of explanation.
The titles of the works referred to will be found in the Bibliography
at the end of the volume. In this list the authors’ names are arranged
alphabetically and the papers of each author are in chronological
order. The numbers in brackets after the author’s name in the
footnotes, and before his name in the bibliographical list, refer to
the year of publication. Except in cases where the works were published
prior to 1800, the first two figures are omitted: thus Ward (84) refers
to a paper published by L. F. Ward in 1884. This system was suggested
by Dr H. H. Field in the _Biologisches Centralblatt_, vol. XIII.
1893, p. 753. (_Ueber die Art der Abfassung naturwissenschaftlicher
Litteraturverzeichnisse._)
=PART I. GENERAL.=
CHAPTER I.
HISTORICAL SKETCH.
“But particular care ought to be had not to consult or take
relations from any but those who appear to have been both long
conversant in these affairs, and likewise persons of Sobriety,
Faithfulness and Discretion, to avoid the being misled and
imposed upon either by falsehood, or the ignorance, credulity,
and fancifulness, that some of these people are but too obnoxious
unto.” JOHN WOODWARD, 1728.
The scientific study of fossil plants dates from a comparatively recent
period, and palaeobotany has only attained a real importance in the
eyes of botanists and geologists during the last few decades of the
present century. It would be out of place, in a short treatise like
the present, to attempt a detailed historical sketch, or to give an
adequate account of the gradual rise and development of this modern
science. An excellent _Sketch of Palaeobotany_ has recently been drawn
up by Prof. Lester Ward[1], of the United States Geological Survey, and
an earlier historical retrospect may be found in the introduction to
an important work by an eminent German palaeobotanist, the late Prof.
Göppert[2]. In the well-known work by Parkinson on _The Organic Remains
of a Former World_[3] there is much interesting information as to the
early history of our knowledge of fossil plants, as well as a good
exposition of the views held at the beginning of this century.
[Sidenote: FOSSIL PLANTS AND THE FLOOD.]
As a means of bringing into relief the modern development of the
science of fossil plants, we may briefly pass in review some of the
earlier writers, who have concerned themselves in a greater or less
degree with a descriptive or speculative treatment of the records of a
past vegetation. In the early part of the present century, and still
more in the eighteenth century, the occurrence of fossil plants and
animals in the earth’s crust formed the subject of animated, not to
say acrimonious, discussion. The result was that many striking and
ingenious theories were formulated as to the exact manner of formation
of fossil remains, and the part played by the waters of the deluge in
depositing fossiliferous strata. The earlier views on fossil vegetables
are naturally bound up with the gradual evolution of geological
science. It is from Italy that we seem to have the first glimmering
of scientific views; but we are led to forget this early development
of more than three hundred years ago, when we turn to the writings
of English and other authors of the eighteenth century. “Under these
white banks by the roadside,” as a writer on Verona has expressed it,
“was born, like a poor Italian gipsy, the modern science of geology.”
Early in the sixteenth century the genius of Leonardo da Vinci[4]
compelled him to adopt a reasonable explanation of the occurrence of
fossil shells in rocks far above the present sea-level. Another Italian
writer, Fracastaro, whose attention was directed to this matter by
the discovery of numerous shells brought to light by excavations at
Verona, expressed his belief in the organic nature of the remains, and
went so far as to call in question the Mosaic deluge as a satisfactory
explanation of the deposition of fossil-bearing strata.
The partial recognition by some observers of the true nature of fossils
marks the starting point of more rational views. The admission that
fossils were not mere sports of nature, or the result of some wonderful
‘vis lapidifica,’ was naturally followed by numerous speculations
as to the manner in which the remains of animals and plants came
to be embedded in rocks above the sea-level. For a long time, the
‘universal flood’ was held responsible by nearly all writers for the
existence of fossils in ancient sediments. Dr John Woodward, in his
_Essay toward a Natural History of the Earth_, propounded the somewhat
revolutionary theory, that “the whole terrestrial globe was taken all
to pieces and dissolved at the Deluge, the particles of stone, marble,
and all solid fossils dissevered, taken up into the water, and there
sustained together with sea-shells and other animal and vegetable
bodies: and that the present earth consists, and was formed out of that
promiscuous mass of sand, earth, shells, and the rest falling down
again, and subsiding from the water[5].” In common with other writers,
he endeavoured to fix the exact date of the flood by means of fossil
plants. Speaking of some hazel-nuts, which were found in a Cheshire
moss pit, he draws attention to their unripened condition, and adds:
“The deluge came forth at the end of May, when nuts are not ripe.” As
additional evidence, he cites the occurrence of “Pine cones in their
vernal state,” and of some Coal-Measure fossils which he compares with
Virginian Maize, “tender, young, vernal, and not ripened[6].” Woodward
(1665–1728) was Professor of Physic in Gresham College; he bequeathed
his geological collections to the University of Cambridge, and founded
the Chair which bears his name.
Another writer, Mendes da Costa, in a paper in the _Philosophical
Transactions_ for 1758, speaks of the impressions of “ferns and
reed-like plants” in the coal-beds, and describes some fossils
(_Sigillaria_ and _Stigmaria_) as probably unknown forms of plant
life[7].
Here we have the suggestion that in former ages there were plants
which differed from those of the present age. Discussing the nature
of some cones (_Lepidostrobi_) from the ironstone of Coalbrookdale
in Shropshire, he concludes: “I firmly believe these bodies to be of
vegetable origin, buried in the strata of the Earth at the time of the
universal deluge recorded by Moses.” Scheuchzer of Zurich, the author
of one of the earliest works on fossil plants and a “great apostle
of the Flood Theory,” figures and describes a specimen as an ear of
corn, and refers to its size and general appearance as pointing to the
month of May as the time of the deluge[8]. Another English writer, Dr
Parsons, in giving an account of the well-known ‘fossil fruits and
other bodies found in the island of Sheppey,’ is disposed to dissent
from Woodward’s views as to the time of the flood. He suggests that the
fact of the Sheppey fruits being found in a perfectly ripe condition,
points to the autumn as the more probable time for the occurrence of
the deluge[9].
In looking through the works of the older writers, and occasionally
in the pages of latter-day contributors, we frequently find curiously
shaped stones, mineral markings on rock surfaces, or certain fossil
animals, described as fossil plants. In Plot’s _Natural History of
Oxfordshire_, published in 1705, a peculiarly shaped stone, probably a
flint, is spoken of as one of the ‘Fungi lethales non esculenti[10]’;
and again a piece of coral[11] is compared with a ‘Bryony root broken
off transversely.’ On the other hand, that we may not undervalue
the painstaking and laborious efforts of those who helped to lay
the foundations of modern science, we may note that such authors as
Scheuchzer and Woodward were not misled by the moss-like or dendritic
markings of oxide of manganese on the surface of rocks, which are not
infrequently seen to-day in the cabinets of amateurs as specimens of
fossil plants.
The oldest figures of fossil plants from English rocks which are drawn
with any degree of accuracy are those of Coal-Measure ferns and other
plants in an important work by Edward Lhwyd published at Oxford in
1760[12].
Passing beyond these prescientific speculations, brief reference may
be made to some of the more eminent pioneers of palaeobotany. The
Englishman Artis[13] deserves mention for the quality rather than the
quantity of his contributions to Palaeozoic botany; and among American
authors Steinhauer’s[14] name must hold a prominent place in the list
of those who helped to found this branch of palaeontology. Among
German writers, Schlotheim stands out prominently as one who first
published a work on fossil plants which still remains an important
book of reference. Writing in 1804, he draws attention to the neglect
of fossils from a scientific standpoint; they are simply looked upon,
he says, as “unimpeachable documents of the flood[15].” His book
contains excellent figures of many Coal-Measure plants, and we find in
its pages occasional comparisons of fossil species with recent plants
of tropical latitudes. Among the earlier authors whose writings soon
become familiar to the student of fossil plants, reference must be
made to Graf Sternberg, who was born three years before Schlotheim,
but whose work came out some years later than that of the latter.
His great contribution to Fossil Botany entitled _Versuch einer
geognostisch-botanischen Darstellung der Flora der Vorwelt_, was
published in several parts between the years 1820 and 1838; it was
drawn up with the help of the botanist Presl, and included a valuable
contribution by Corda[16]. In addition to descriptions and numerous
figures of plants from several geological horizons, this important work
includes discussions on the formation of coal, with observations on the
climates of past ages.
[Sidenote: STERNBERG AND BRONGNIART.]
Sternberg endeavoured to apply to fossil plants the same methods of
treatment as those made use of in the case of recent species. About
the same time as Sternberg’s earlier parts were published, Adolphe
Brongniart[17] of Paris began to enrich palaeobotanical science by
those splendid researches which have won for him the title of the
“Father of palaeobotany.” In Brongniart’s _Prodrome_, and _Histoire des
végétaux fossiles_, and later in his _Tableau des genres de végétaux
fossiles_, we have not merely careful descriptions and a systematic
arrangement of the known species of fossil plants, but a masterly
scientific treatise on palaeobotany in its various aspects, which
has to a large extent formed the model for the best subsequent works
on similar lines. From the same author, at a later date, there is at
least one contribution to fossil plant literature which must receive
a passing notice even in this short sketch. In 1839 he published an
exhaustive account of the minute structure of one of the well-known
Palaeozoic genera, _Sigillaria_; this is not only one of the best
of the earliest monographs on the histology of fossil species, but
it is one of the few existing accounts of the internal structure of
this common type[18]. The fragment of a Sigillarian stem which formed
the subject of Brongniart’s memoir is in the Natural History Museum
in the Jardin des Plantes, Paris. It affords a striking example of
the perfection of preservation as well as of the great beauty of the
silicified specimens from Autun, in Central France. Brongniart was
not only a remarkably gifted investigator, whose labours extend over
a period connecting the older and more crude methods of descriptive
treatment with the modern development of microscopic analysis, but
he possessed the power of inspiring a younger generation with a
determination to keep up the high standard of the palaeobotanical
achievements of the French School. In some cases, indeed, his
disciples have allowed a natural reverence for the Master to warp
their scientific judgement, where our more complete knowledge has
naturally led to the correction of some of Brongniart’s conclusions.
Without attempting to follow the history of the science to more recent
times, the names of Heer, Lesquereux, Zigno, Massalongo, Saporta and
Ettingshausen should be included among those who rendered signal
service to the science of fossil plants. The two Swiss writers,
Heer[19] and Lesquereux[20], contributed numerous books and papers
on palaeobotanical subjects, the former being especially well known
in connection with the fossil floras of Switzerland and of Arctic
lands, and the latter for his valuable writings on the fossil plants
of his adopted country, North America. Zigno[21] and Massalongo[22]
performed like services for Italy, and the Marquis of Saporta’s name
will always hold an honourable and prominent position in the list of
the pioneers of scientific palaeobotany; his work on the Tertiary and
Mesozoic floras of France being specially noteworthy among the able
investigations which we owe to his ability and enthusiasm[23]. In Baron
Ettingshausen[24] we have another representative of those students
of ancient vegetation who have done so much towards establishing the
science of fossil plants on a philosophical basis.
As in other fields of Natural Science, so also in a marked degree in
fossil botany, a new stimulus was given to scientific inquiry by the
application of the microscope to palaeobotanical investigation. In
1828 Sprengel published a work entitled _Commentatio de Psarolithis,
ligni fossilis genere_[25]; in which he dealt in some detail with
the well-known silicified fern-stems of Palaeozoic age, from Saxony,
basing his descriptions on the characteristics of anatomical structure
revealed by microscopic examination.
[Sidenote: THE INTERNAL STRUCTURE OF FOSSIL PLANTS.]
In 1833 Henry Witham of Lartington brought out a work on _The Internal
Structure of Fossil Vegetables_[26]; this book, following the much
smaller and less important work by Sprengel, at once established
palaeobotany on a firmer scientific basis, and formed the starting
point for those more accurate methods of research, which have yielded
such astonishing results in the hands of modern workers. In the
introduction Witham writes, “My principal object in presenting this
work to the public, is to impress upon geologists the advantage of
attending more particularly to the intimate organization of fossil
plants; and should I succeed in directing their efforts towards
the elucidation of this obscure subject, I shall feel a degree of
satisfaction which will amply repay my labour[27].”
On another page he writes as follows,—“From investigations made by
the most active and experienced botanical geologists, we find reason
to conclude that the first appearance of an extensive vegetation
occurred in the Carboniferous series; and from a recent examination
of the mountain-limestone groups and coal-fields of Scotland, and the
north of England, we learn that these early vegetable productions, so
far from being simple in their structure, as had been supposed, are
as complicated as the phanerogamic plants of the present day. This
discovery necessarily tends to destroy the once favourite idea, that,
from the oldest to the most recent strata, there has been a progressive
development of vegetable and animal forms, from the simplest to the
most complex[28].” Since Witham’s day we have learnt much as to the
morphology of Palaeozoic plants, and can well understand the opinions
to which he thus gives expression.
It would be difficult to overrate the immense importance of this
publication from the point of view of modern palaeobotany.
The art of making transparent sections of the tissues of fossil
plants seems to have been first employed by Sanderson, a lapidary,
and it was afterwards considerably improved by Nicol[29]. This most
important advance in methods of examination gave a new impetus to
the subject, but it is somewhat remarkable that the possibilities of
the microscopical investigation of fossil plants have been but very
imperfectly realised by botanical workers until quite recent years. As
regards such a flora as that of the Coal-Measures, we can endorse the
opinion expressed at the beginning of the century in reference to the
study of recent mosses—“Ohne das Göttergeschenk des zusammengesetzten
Mikroskops ist auf diesem Felde durchaus keine Ernte[30].” A useful
summary of the history of the study of internal structure is given
by Knowlton in a memoir published in 1889[31]. Not long after
Witham’s book was issued there appeared a work of exceptional merit
by Corda[32], in which numerous Palaeozoic plants are figured and
fully described, mainly from the standpoint of internal structure.
This author lays special stress on the importance of studying the
microscopical structure of fossil plants.
[Sidenote: ENGLISH PALAEOBOTANISTS.]
Without pausing to enumerate the contributions of such well-known
continental authors as Göppert, Cotta, Schimper, Stenzel, Schenk and
a host of others, we may glance for a moment at the services rendered
by English investigators to the study of palaeobotanical histology.
Unfortunately we cannot always extend our examination of fossil plants
beyond the characters of external form and surface markings; but in
a few districts there are preserved remnants of ancient floras in
which fragments of stems, roots, leaves and other structures have been
petrified in such a manner as to retain with wonderful completeness
the minute structure of their internal tissues. During the deposition
of the coal seams in parts of Yorkshire and Lancashire the conditions
of fossilisation were exceptionally favourable, and thus English
investigators have been fortunately placed for conducting researches on
the minute anatomy of the Coal-Measure plants. The late Mr Binney of
Manchester did excellent service by his work on the internal structure
of some of the trees of the Coal Period forests. In his introductory
remarks to a monograph on the genus _Calamites_, after speaking of
the desirability of describing our English specimens, he goes on to
say, “When this is done, we are likely to possess a literature on our
Carboniferous fossils worthy of the first coal-producing country[33].”
The continuation and extension of Binney’s work in the hands of
Carruthers, Williamson, and others, whose botanical qualifications
enabled them to produce work of greater scientific value, has gone far
towards the fulfilment of Binney’s prophecy.
[Sidenote: DIFFICULTIES OF IDENTIFICATION.]
In dealing with the structure of Palaeozoic plants, we shall be
under constant obligation to the splendid series of memoirs from
the pen of Prof. Williamson[34]. As the writer of a sympathetic
obituary notice has well said: “In his fifty-fifth year he began
the great series of memoirs which mark the culminating point of his
scientific activity, and which will assure to him, for all time, in
conjunction with Brongniart, the honourable title of a founder of
modern Palaeobotany[35].” If we look back through a few decades,
and peruse the pages of Lindley and Hutton’s classic work[36] on
the Fossil flora of Great Britain, a book which is indispensable
to fossil botanists, and read the description of such a genus as
_Sigillaria_ or _Stigmaria_; or if we extend our retrospect to an
earlier period and read Woodward’s description of an unusually good
specimen of a _Lepidodendron_, and finally take stock of our present
knowledge of such plants, we realise what enormous progress has been
made in palaeobotanical studies. Lindley and Hutton, in the preface
to the first volume of the Flora, claim to have demonstrated that
both _Sigillaria_ and _Stigmaria_ were plants with “the highest
degree of organization, such as _Cactaeae_, or _Euphorbiaceae_, or
even _Asclepiadeae_”; Woodward describes his _Lepidodendron_ (Fig. 1)
as “an ironstone, black and flat, and wrought over one surface very
finely, with a strange cancellated work[37].” Thanks largely to the
work of Binney, Carruthers, Hooker, Williamson, and to the labours
of continental botanists, we are at present almost as familiar with
_Lepidodendron_ and several other Coal-Measure genera as with the
structure of a recent forest tree. While emphasizing the value of the
microscopic methods of investigation, we are not disposed to take such
a hopeless view of the possibilities of the determination of fossil
forms, in which no internal structure is preserved, as some writers
have expressed. The preservation of minute structure is to be greatly
desired from the point of view of the modern palaeobotanist, but he
must recognise the necessity of making such use as he can of the
numberless examples of plants of all ages, which occur only in the form
of structureless casts or impressions.
[Illustration: FIG. 1. Four leaf-cushions of a _Lepidodendron_. Drawn
from a specimen in the Woodward Collection, Cambridge. (Nat. size.)]
In looking through the writings of the earlier authors we cannot help
noticing their anxiety to match all fossil plants with living species;
but by degrees it was discovered that fossils are frequently the
fragmentary samples of extinct types, which can be studied only under
very unfavourable conditions. In the absence of those characters on
which the student of living plants relies as guides to classification,
it is usually impossible to arrive at any trustworthy conclusions as
to precise botanical affinity. Brongniart and other authors recognised
this fact, and instituted several convenient generic terms of a purely
artificial and provisional nature, which are still in general use. The
dangers and risks of error which necessarily attend our attempts to
determine small and imperfect fragments of extinct species of plants,
will be briefly touched on in another place.