THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID
A

THE

ANCIENT LIFE-HISTORY

OF

THE EARTH

International Science library
THE

ANCIENT LIFE-HISTORY

OF

THE EARTH

A COMPREHENSIVE OUTLINE OF THE PRINCIPLES AND LEADING
FACTS OP PALAEONTOLOGICAL SCIENCE

BY

H. 'ALLEYNE NICHOLSON

M. D., D. Sc., M.A.. PH.D. (Gorr.), F. R. S. E., F. L. S.

PROFESSOR OF NATURAL HISTORY IN THt
UNIVERSITY OF ST. ANDREWS •

Tiderner Company

JSooh flftanutactur.:re

fc r o n , ©bio

PALEO,
L1BR.

Gift of C. A. Kofoid

WERNER EDITION

. a

£ARTH
SCIENCES
11BRABY

PREFACE.

THE study of Palaeontology, or the science which is
concerned with the living beings which flourished upon
the globe during past periods of its history, may be
pursued by two parallel but essentially distinct paths.
By the one method of inquiry, we may study the ana-
tomical characters and structure of the innumerable
extinct forms of life which lie buried in the rocks
simply as so many organisms, with but a slight and
secondary reference to the time at which they lived.
By the other method, fossil animals are regarded prin-
cipally as so many landmarks in the ancient records of
the world, and are studied historically and as regards
their relations to the chronological succession of the
strata in which they are entombed. In so doing, it is
of course impossible to wholly ignore their structural
characters, and their relationships with animals now
living upon the earth ; but these points are held to
occupy a subordinate place, and to require nothing
more than a comparatively general attention.

In a former work, the Author has endeavored to
furnish a summary of the more important facts of
Palaeontology regarded in its strictly scientific aspect,

(v)

M332350

vi PREFACE.

as a mere department of the great science of Biology.
The present work, on the other hand, is an attempt to
treat Palaeontology more especially from its historical
side, and in its more intimate relations with Geology.
In accordance with this object, the introductory por-
tion of the work is devoted to a consideration of the
general principles of Palaeontology, and the bearings
of this science upon various geological problems — such
as the mode of formation of the sedimentary rocks,
the reactions of living beings upon the crust of the
earth, and the sequence in time of the fossiliferous for-
mations. The second portion of the work deals exclu-
sively with Historical Palaeontology, each formation
being considered separately, as regards its lithological
nature and subdivisions, its relations to other forma-
tions, its geographical distribution, its mode of origin,
and its characteristic life-forms.

In the consideration of the characteristic fossils of
each successive period, a general account is given of
their more important zoological characters and their
relations to living forms ; but the technical language of
Zoology has been avoided, and the aid of illustrations
has been freely called into use. It may therefore be
hoped that the work may be found to be available for
the purposes of both the Geological and the Zoological
student; since it is essentially an outline of Historical
Palaeontology, and the student of either of the above-
mentioned sciences must perforce possess some knowl-
edge of the last. Whilst primarily intended for stu-
dents, it may be added that the method of treatment
adopted has been so far untechnical as not to render
the work useless to the general reader who may desire
to acquire some knowledge of the subject of such vast
and universal interest.

In carrying out the object which he has held before
him, the Author can hardly expect, from the nature of

PREFACE. vii

the materials with which he has to deal, that he has
kept himself absolutely clear of errors, both of omis-
sion and commission. The subject, however, is one to
which he has devoted the labor of many years, both
in studying the researches of others and in personal
investigations of his own ; and he can only trust that
such errors as may exist will be found to belong chiefly
to the former class, and to be neither serious nor
numerous. It need only be added that the work is
necessarily very limited in its scope, and that the ne-
cessity of not assuming a thorough previous acquaint-
ance with Natural History in the reader has inexorably
restricted its range still further. The Author does not,
therefore, profess to have given more than a merely
general outline of the subject; and those who desire to
obtain a more minute and detailed knowledge of
Palaeontology, must have recourse to other and more
elaborate treatises.

UNITED COLLEGE, ST. ANDREWS.
October 2, 1876.

CONTENTS.

PART I.

PRINCIPLES OF PALAEONTOLOGY.
INTRODUCTION.

PAGE

The general objects of geological science — The older theories
of catastrophistic and intermittent action — The more
modern doctrines of continuous and uniform action —
Bearing of these doctrines respectively on the origin of
the existing terrestrial order — Elements of truth in
Catastrophism— General truth of the doctrine of Con-
tinuity— Geological time . . . ." I-IO

CHAPTER I.

Definition of Palaeontology — Nature of Fossils — Different
processes of f osilization 10-14

CHAPTER II.

Aqueous and igneous rocks — General characters of the
sedimentary rocks — Mode of formation of the sedi-
mentary rocks — Definition of the term " formation " —
Chief divisions of the aqueous rocks — Mechanically-
formed rocks, their characters and mode of origin —
Chemically and organically formed rocks — Calcareous
rocks — Chalk, its microscopic structure and mode of
formation — Limestone, varieties, structure, and origin —
Phosphate of lime — Concretions — Sulphate of lime —
Silica and siliceous deposits of various kinds — Green-
sands — Red clays — Carbon and carbonaceous deposits. .15-38
(ix)

x CONTENTS.

CHAPTER III.

Chronological succession of the fossiliferous rocks — Tests
of age of strata— Value of Palaeontological evidence in
stratigraphical Geology — General sequence of the great
formations 38-45

CHAPTER IV.

The breaks in the palaeontological and geological record —
Use of the term " contemporaneous " as applied to
groups of strata — General sequence of strata and of life-
forms interfered with by more or less extensive gaps —
Unconformability — Phenomena implied by this — Causes
of the imperfection of the palaeontological record 45~53

CHAPTER V.

Conclusions to be drawn from fossils — Age of rocks — Mode
of origin of any fossiliferous bed — Fluviatile, lacustrine,
and marine deposits — Conclusions as to climate — Proofs
of elevation and subsidence of portions of the earth's
crust derived from fossils 53-58

CHAPTER VI.

The biological relations of fossils — Extinction of life-forms
— Geological range of different species — Persistent types
of life — Modern origin of existing animals and plants —
Reference of fossil forms to the existing primary divi-
sions of the animal kingdom — Departure of the older
types of life from those now in existence — Resemblance
of the fossils of a given formation to those of the for-
mation next above and next below — Introduction of new
life-forms 58-62

PART II.
HISTORICAL PALAEONTOLOGY.

CHAPTER VII.

The Laurentian and Huronian periods — General nature,
divisions, and geographical distribution of the Lauren-
tian deposits — Lower and Upper Laurentian — Reasons
for believing that the Laurentian rocks are not azoic
based upon their containing limestones, beds of oxide
of iron, and graphite — The characters, chemical com-
position, and minute structure of Eozoon Canadense —
Comparison of Eozoon with existing Foraminifcra —
Archceosphcerince — Huronian formation — Nature and dis-
tribution of Huronian deposits — Organic remains of the
Huronian— Literature 65-77

CONTENTS. xi

CHAPTER VIII.

The Cambrian period — General succession of Cambrian de-
posits in Wales — Lower Cambrian and Upper Cambrian
— Cambrian deposits of the continent of Europe and
North America — Life of the Cambrian period — Fucoids
— Eophyton — Oldhamia — Sponges — Echinoderms — An -
nelides — Crustaceans — Structure of Trilobites — Brachio-
pods, Gasteropods, and Bivalves — Cephalopods — Litera-
ture 77-91

CHAPTER IX.

The Lower Silurian period — The Silurian rocks generally —
Limits of Lower and Upper Silurian — General succession,
subdivisions, and characters of the Lower Silurian rocks
of Wales — General succession, subdivisions and charac-
ters of the Lower Silurian rocks of the North American
continent — Life of the period — Fucoids — Protozoa —
Graptolites — Structure of Graptolites — Corals — General
structure of Corals — Crinoids — Cystideans — General
character of Cystideans — Annelides — Crustaceans — Poly-
zoa — Brachiopods — Bivalve and Univalve Molluscs —
Chambered Cephalopods — General characters of the
Cephalopoda — Conodonts 91-116

CHAPTER X.

The Upper Silurian period — General succession of the Upper
Silurian deposits of Wales — Upper Silurian deposits of
North America — Life of the Upper Silurian — Plants —
Protozoa — Graptolites — Corals— Crinoids — General struc-
ture of Crinoids — Star-fishes — Annelides — Crustaceans —
Eurypterids — Polyzoa — Brachiopods — Structure of Bra-
chiopods— Bivalves and Univalves — Pteropods — Cephal-
opods—Fishes— Silurian literature 116-134

CHAPTER XI.

The Devonian period — Relation between the Old Red Sand-
stone and the marine Devonian deposits — The Old Red
Sandstone of Scotland — The Devonian strata of Devon-
shire— Sequence and subdivisions of the Devonian de-
posits of North America — Life of the period — Plants —
Protozoa — Corals — Crinoids — Pentremites — Annelides —
Crustaceans — Insects — Polyzoa — Brachiopods — Bivalves
— Univalves — Pteropods — Cephalopods — Fishes — General
divisions of the Fishes — Palaeontological evidence as to
the independent existence of the Devonian system as a
distinct formation — Literature 134-160

xii CONTENTS.

CHAPTER XII.

The Carboniferous period — Relations of Carboniferous rocks
to Devonian — The Carboniferous Limestone or Sub-Car-
boniferous series — The Millstone-grit and the Coal-
measures — Life of the period — Structure and mode of
formation of Coal — Plants of the Coal 160-174

CHAPTER XIII.

Animal life of the Carboniferous period — Protozoa — Corals —
Crinoids — Pentremites — Structure of Pentremites —
Echinoids — Structure of Echinoidea — Annelides — Crus-
tacea— Insects — Arachnids — Myriapods — Polyzoa — Bra-
chiopods — Bivalves and Univalves — Cephalopods — Fishes
— Labyrinthodont Amphibians — Literature 174-196

CHAPTER XIV.

The Permian period — General succession,, characters, and
mode of formation of the Permian deposits — Life of the
period — Plants — Protozoa — Corals — Echinoderms — Anne-
lides— Crustaceans — Polyzoa — Brachiopods — Bivalves —
Univalves — Pteropods — Cephalopods — Fishes — Amphi-
bians— Reptiles — Literature 196-208

CHAPTER XV.

The Triassic period — General characters and subdivisions of
the Trias of the Continent of Europe and Britain — Trias
of North America — Life of the period — Plants — Echin-
oderms— Crustaceans — Polyzoa — Brachiopods — Bivalves
— Univalves — Cephalopods — Intermixture of Palaeozoic
with Mesozoic types of Molluscs — Fishes — Amphibians —
Reptiles — Supposed footprints of Birds — Mammals —
Literature . . '. 208-232

CHAPTER XVI.

The Jurassic period — General sequence and subdivision of
the Jurassic deposits in Britain — Jurassic rocks of North
America — Life of the period — Plants — Corals — Echino-
derms— Crustaceans — Insects — Brachiopods — Bivalves —
Univalves — Pteropods — Tetrabranchiate Cephalopods —
Dibranchiate Cephalopods — Fishes — Reptiles — Birds —
Mammals — Literature 232-264

CHAPTER XVII.

The Cretaceous period — General succession and subdivisions
of the Cretaceous rocks in Britain — Cretaceous rocks of
North America — Life of the period — Plants — Protozoa —
Corals — Echinoderms — Crustaceans — Polyzoa — Brachio-
pods— Bivalves — Univalves — Tetrabranchiate and Dibran-
chiate Cephalopods — Fishes — Reptiles — Birds — Litera-
ture 264-293

CONTENTS. xiii

CHAPTER XVIII.

The Eocene period — Relation between the Kainozoic and
Mesozoic rocks in Europe and in North America — Classi-
fication of the Tertiary deposits — The sequence and sub-
divisions of the Eocene rocks of Britain and France —
Eocene strata of the United States — Life of the period —
Plants — Foraminif era — Corals — Echinoderms — Mollusca
— Fishes — Reptiles — Birds — Mammals 294-316

CHAPTER XIX.

The Miocene period — Miocene strata of Britain — Of France
—Of Belgium— Of Austria— Of Switzerland— Of Ger-
many— Of Greece — Of India — Of North America — Of
the Arctic regions — Life of the period — Vegetation of the
Miocene period — Foraminif era — Corals — Echinoderms —
Articulates — Mollusca — Fishes — Amphibians — Reptiles —
Mammals 316-334

CHAPTER XX.

The Pliocene period — Pliocene deposits of Britain — Of Eu-
rope— Of North America — Life of the period — Climate
of the period as indicated by the Invertebrate animals —
The Pliocene Mammalia — Literature relating to the
Tertiary deposits and their fossils 335-346

CHAPTER XXI.

The Post-Pliocene period — Division of the Quaternary de-
posits into Post-Pliocene and Recent — Relations of the
Post-Pliocene deposits of the northern hemisphere to the
" Glacial period " — Pre-Glacial deposits — Glacial deposits
— Arctic Mollusca in Glacial beds — Post-Glacial deposits
— Nature and mode of formation of high-level and low-
level gravels — Nature and mode of formation of cavern-
deposits — Kent's Cavern — Post-Pliocene deposits of the
southern hemisphere 346-357

CHAPTER XXII.

Life of the Post-Pliocene period — Effect of the coming on
and departure of the Glacial period upon the animals
inhabiting the northern hemisphere — Birds of the Post-
Pliocene — Mammalia of the Post-Pliocene — Climate of
the Post-Glacial period as deduced from the Post-Glacial
Mammals — Occurrence of the bones and implements of
Man in Post-Pliocene deposits in association with the
remains of extinct Mammalia — Literature relating to the
Post- Pliocene period 358-380

xiv CONTENTS.

CHAPTER XXIII.

The succession of life upon the globe — Gradual and succes-
sive introduction of life-forms — What is meant by
" lower " and " higher " groups of animals and plants —
Succession in time of the great groups of animals in the
main corresponding with their zoological order — Identi-
cal phenomena in the vegetable kingdom — Persistent
types of life — High organization of many early forms —
Bearings of Palaeontology on the general doctrine of
Evolution 381-388

APPENDIX. — Tabular view of the chief Divisions of the Ani-
mal Kingdom 389-392

GLOSSARY 393-415

INDEX 416-430

LIST OF ILLUSTRATIONS.

FIG.

1. Cast of Trigonia longa,

2. Microscopic section of

the wood of a fossil
Conifer .............

3. Microscopic section of

the wood of the Larch

4. Section of Carbonife-

rous strata, Kinghorn,
Fife ...............

5. Diagram illustrating the

formation of strati-
fied deposits .........

6. Microscopic section of

a calcareous breccia..

7. Microscopic section of

White Chalk ........

8. Organisms in Atlantic

Ooze ...............

9. Crinoidal marble ......

10. Piece of Nummulitic

limestone, Pyramids.

11. Microscopic section of

Foraminif eral _ lime-
stone — Carboniferous
America ............

12. Microscopic section of

Lower Silarian lime-
stone ...............

13. Microscopic section of

oolitic limestone, Ju-
rassic ..............

14. Microscopic section of

oolitic limestone, car-
boniferous ..........

15. Organisms in Barba-

does earth ..........

16. Organisms in Richmond

earth ...............

17. Ideal section of the

crust of the earth...

18. Unconformable June-

tion of Chalk and Eo-
cene rocks ..........

19. Erect trunk of a Sigil-

laria ...............

20. Diagrammatic section

13

14

14

16

17
20
23

24

25

26

28
28
30

31

34
34
44

50

55
(xv)

FIG.

21.

22.

23-

24.

27.

28.
29.
30.
31-

32.

33-
34-

35-
36.

39-

40.

41.
42.
43-
44-
45-
46.
47-

PAGE

of the Laurentian
rocks 66

Microscopic section of

Laurentian limestone 67
Fragment of a mass of

Eozoon Canadense.. 69
Diagram illustrating the

structure of EozoVn. 70
Microscopic section of

Eozo'dn Canadense... 71
Nonionina and Gromia 72
Group of shells of liv-
ing Foraminif era .... 73
Diagrammatic section

of Cambrian strata... 78
Eophyton Linneanum. . 81

Oldhamia antiqua 82

Scolithus Canadensis.. 83
Group of Cambrian

Trilobites 85

Group of characteristic

Cambrian fossils 88

Fragment of Dictyo-

nema sociale 89

Generalized section ^of
the Lower Silurian

rocks of Wales 95

Generalized section of
the Lower Silurian
rocks of North Ame-
rica 97

Licrophycus Ottawaen-

sis 98

Astylospongia prcemorsa 99
Stromatopora rugosa.. loo
Dichograptus octobra-

chiatus IO2

Didymograptus diava-

ricatus 103

Diplograptus pristis... 103
Phyllograptus typus... 103

Zaphrentis Stokesi 105

Strombodes pentagonus 105
Columnaria alveolata.. 106
Group of Cystideans.. 107
Group of Lower Silu-
rian Crustaceans... 108

XVI

LIST OF ILLUSTRATIONS.

48. Ptilodictya falciformis 109

49. Ptilodictya S chaff eri. . 109

50. Group of Lower Silu-

rian Brachiopods. . . . no

51. Group of Lower Silu-

rian Brachiopods... in

52. Murchisonia gracilis... 112

53. Bellerophon argo 113

54. Maclurea crenulata... 113

55. Orthoceras crebrisep-

tum 114

56. Restoration of Ortho-

ceras 114

57. Generalized section of

the Upper Silurian
rocks 119

58. Monograptus priodon.. 121

59. Halysites catenularia

and H. agglomerata 122

60. Group of Upper Silu-

rian Star-fishes 123

61. Protaster Sedgwickii.. 123

62. Group of Upper Silu-

rian Crinoids 124

63. Planolites vulgaris.... 125

64. Group of Upper Silu-

rian Trilobites 126

65. Pterygotus Anglicus... 127

66. Group of Upper Silu-

rian Polyzoa 128

67. Spirifera hyst erica 128

68. Group of Upper Silu-

rian Brachiopods 129

69. Group of Upper Silu-

rian Brachiopods.... 129

70. Pentamerus Knightii. . 130

71. Cardiola interrupta, C.

fibrosa, and Pterinaa
subfalcata 130

72. Group of Upper Silu-

rian Univalves 131

73. Tentaculites ornatus... 131

74. Pteraspis Banksii 132

75. Onchus tenuistriatus

and Thelodus 132

76. Generalized section of

the Devonian rocks

of North America. . . 139

77. Psilophyton prince ps. . 140

78. Prototaxites Logani. . . 141

79. Stromatopora tubercu-

lata 142

80. Cystiphyllum vesiculo-

sum ................ 143

81. Zaphrentis cornicula. 143

82. Heliophyllum exiguum 143

83. Crepidophyllum Archi-

aci. . . . ............. 144

84. Favorsites Gothlandica 145

85. Favo sites hemisph&r-

ica .................. 145

86. Spirorbis omphalodes

and S. Arkonensis. . . 146
Spirorbis laxus and s.

spinulifera .......... 146

Group of Devonian

Trilobites

87.
88.
89. Wing of Platephem-

147

147.

era antiqua ..........

90. Clathropora intertexta 148

91. Ceriopora Hamilton-

ensis ................ 148

92. Fenestella magnifica.. 148

93. Retepora Phillip si ____ 148

94. Fenestella cribrosa... 148

95. Spirifera sculptilis . . . 149

96. Spirifera mucronata 149

97. Atrypa reticularis. ... 150

98. Strophomena rhom-

boidalis ............. 150

99. Platyceras dumosium 151

100. Conularia ornata ..... 151

101. Clymenia Sedwickii. . 152

102. Group of Fishes from

the Devonian rocks

of North America.. 154

103. Cephalaspis Lyellii. . . 155

104. Pterichthys cornutus 156

105. Polypterus and Osteo-

lepis ................ 157

1 06. Holoptychius nobilis-

simus. .............. 158

107. Generalized section of
' the Carboniferous

rocks of the North

of England ......... 164

108. Odontopteris Schloth-

eimii ............... 168

109. Catamites cannafor-

mis ................. 169

no. Lepidodendron Stern-

bergii ............... 171

1 1 r. Sigillaria Gr&seri ..... 172

112. Stigmaria ficoides ---- 173

LIST OF ILLUSTRATIONS.

113. Trigonocarpum Ova-

turn 173

114. Microscopic section of

Foraminiferal lime-
stone— Carboniferous,
North America 175

115. Fusulina cylindrica. . . 176

116. Group of Carbonifer-

ous Corals 178

117. Platycrinus triconta-

dactylus 179

118. Pentremites pyrifor-

mis and P. conoideus 180

119. Archceocidaris ellipti-

cus 181

120. Spirorbis Carbonar-

ms 182

121. Prestwichia rotund-

data t 183

122. Group of Carbonifer-

ous Crustaceans 184

123. Cyclophthalmus senior 185

124. Xylobius sigillarice. . . 186

125. Haplophlebium Barn-

esi 186

126. Group of Carbonifer-

ous Polyzoa 187

127. Group of Carbonifer-

ous Brachiopoda. . . . 189

128. Pupa vetusta 190

129. Goniatites Fosse? 191

130. Amblypterus macrop-

terus 192

131. Cochliodus contortus. 193

132. Anthracosaurus Rus-

selli 194

!33- Generalized section of

the Permian rocks.. 199

134. Walchia piniformis. . . 200

135. Group of Permian

Brachiopods 202

136. Area antiqua 203

137. Platysomus gibbosus 203

138. Protorosaurus Speneri 205

139. Generalized section of

the Triassic rocks... 211

140. Zamia spiralis 213

141. Triassic Conifers and

Cycads 214

142. Enerinus liliiformis. . . 215

143. Aspidura toricata 215

144. Group of Triassic Bi-

valves 2j6

145. Ceratites nodosus 218

146.

147.
148.

149.
150.
151.
152.

153.
154.

155.

156.
157.
158.
159.
160.

161.
162.

163.

164.
165.

166.
167.
168.
169.
170.

171.
172.
173.

174.
175.
176.

Tooth of Ceratodus

seratus and C. altus 220
Ceratodus Fosteri.... 221
Footprints of Cheiro-

therium ............. 222

Section of tooth of

Labyrinthodont ...... 223

Skull of Mastodon-

saurus .............. 223

Skull of Rhynchosau-

rus ................. 224

Belodon, Nothosaurus,

Palceosaurus, etc., . . . 225
Placodus gigas ....... 226

Skulls of Dicynodon

and Oudenodon. . . . 227
Supposed footprint of

Bird, from the Trias

of Connecticut ...... 228

Lower jaw of Droma-

therium syhestre ---- 229
Molar tooth of Micro-

lestes antiquus ...... 229

'Myrmecobius fasci-

atus ................ 230

Generalized section of

the Juriassic rocks.. 236
Mantellia megaloph-
lla ................. 237

238

Thecosmilia annularis
Pentacrinus fasciculo-

sus ................. 239

Hemicidaris crenula-

ris ................. 240

Eryon arctiformis ---- 241

Group of Jurassic

Brachiopods ...... . . 242

Ostrea Marshii. ...... .243

Gryphcea incurva ..... 243

Diceras arietina ...... 243

Nerincea Goodhallii... 244
Ammonites Humph-

resianus ............ 245

Ammonites bifrons... 245
Beloteuthis subcostata 247
Belemnite restored;

diagram of Belem-

nite ; Belemnites can-

aliculata ............ 248

Tetragonolepsis ...... 248

Aerodus nobilis ...... 249

Ichthyosaurus com-

munis ............... 249

LIST OF ILLUSTRATIONS.

177. Plesiosaurus dolicho-

deirus 251

178. Pterodactylus crassir-

ostris 253

179 Ramphorhynchus

Bucklandi, restored 255

180. Skull of Megalosaurus 256

181. Archaopteryx mac-

rura 259

182. Archceopteryx, restor-

ed 259

183. Jaw of Amphither-

ium Prevostii 261

184. Jaws of Oolitic Mam-

mals 261

185. Generalized section of

the Cretaceous rocks 268

186. Cretaceous Angios-

perms 271

187 Rotalia Boueana 272

188. Siphonia ficus 273

189. Ventriculites simplex 273

190. Synhelia Sharpeana. . 274

191. Galerites albogalerus 275

192. Discoidea cylindrica. . 275

193. Escharina Oceani.... 276

194. TerebratellaAstieriana 276

195. Crania Ignabergenis 277

196. Ostrea Coulom 277

197. Spondylus spinosus.. 278

198. Inoceramus sulcatus 278

199. Hippurites Toucasi-

ana 279

200. Valuta elongata 279

201. Nautilus Danicus. . . . 280

202. Ancyloceras Mather-

onianus 281

203. Turrilites catenatus . . 282

204. Forms of Cretaceous

Ammonitidce 282

205. Belemnitella mucro-

nata 283

206. Tooth of Hybodus. . . 284

207. Fin-spine of Hybodus 284

208. Beryx Lewesiensis and

Osmeroides Mantelli 284

209. Teeth of Iguanodon 286

210. Skull of Mosasaurus-

Camperi 287

211. Chelone Benstedi 289

212. Jaws and vertebrae of

Odontornithes 291

213. Fruit of Nipadites 300

214. Nummulina l&vigata 301

215. Turbinolia sulcata... 302

216. Cardita planicosta 303

217. Typhis tubifer 303

218. Cypraa elegans 303

219. Certhium hexagonum 304

220. Limnaa pyramidalis. . 304

221. Physa columnaris 304

222. Cyclostoma Arnoudii 304

223. Rhombus minimus... 305

224. Otodus obliquus 306

225. Myliobatis Edwardsii 306

226. Upper jaw of Alliga-

tor 307

227. Skull of Odonto-

pteryx toliapicus 308

228. Zeuglodon cetoides. . . 310

229. Palaotherium mag-

num, restored 311

230. Feet of Equida 312

231. Amplotherium com-

mune 313

232. Skull of Dinoceras

mirabilis 314

233. Vespertilio Parisien-

sis.. 315

234. Miocene Palms 319

235. Platanus aceroides... 320

236. Cinnamomum poly-

morphum 320

237. Texularia Meyeriana 322

238. Scutella subrotunda.. 323

239. Hyalea Orbignyana.. 323

240. Tooth of Oxyrhina.. 324

241. Tooth of Carcharo-

don 324

242. Andrias Scheuchzeri 325

243. Skull of Brontother-
ium ingens 327

244. Hippopotamus Sival-

ensis 329

245. Skull of Sivatherium 330

246. Skull of Deinotherium 331

247. Tooth of Elephas

planifrons and of
Mastodon Sivalensis 332

248. Jaw of Pliopithecus.. 334

249. Rhinoceros Etruscus

and R. megarhinus.. 339

250. Molar tooth of Mas-

todon Arvernensis . . 341

251. Molar tooth of Ele-

phas meridionalis . . . 342

LIST OF ILLUSTRATIONS.

252. Molar tooth of Ele-

phas antiquus 342

253. Skull and tooth of

Machairodus cultri-
dens 343

254. Pecten Islandicus 35 l

255. Diagram of high-level

and low-level gravels 353

256. Diagrammatic section

of Cave 356

257. Dinornis elephantopus 360

258. Skull of Diprotodon.. 362

259. Skull of Thylacoleo.. 362

260. Skeleton of Megath-

erium 363

261. Skeleton of Mylodon 365

262. Glyptodon clavipes... 365

263. Skull of Rhinoceros

tichorhinus 366

264. Skeleton of Cervus

megaceros 368

265. Skull of Bos primi-

genius 369

266. Skeleton of Mammoth 371

267. Molar tooth of Mam-

moth 372

268. Skull of Ursus spelaus 373

269. Skull of Hyama spel-

(ua 374

270. Lower jaw of Trog-

ontherium Cuvieri... 375

PART I.

PRINCIPLES OF PALEONTOLOGY.

THE
ANCIENT LIFE-HISTORY

OF

THE EARTH.

INTRODUCTION.

THE LAWS OF GEOLOGICAL ACTION.

UNDER the general title of " Geology " are usually included at
least two distinct branches of inquiry, allied to one another in
the closest manner, and yet so distinct as to be largely capable
of separate study. Geology* in its strictest sense, is the science
which is concerned with the investigation of the materials which
compose the earth, the methods in which those materials have
been arranged, and the causes and modes of origin of these
arrangements. In this limited aspect, Geology is nothing more
than the Physical Geography of the past, just as Physical Geog-
raphy is the Geology of to-day; and though it has to call in
the aid of Physics, Astronomy, Mineralogy, Chemistry, and
other allies more remote, it is in itself a perfectly distinct and
individual study. One has, however, only to cross the thresh-
old of Geology to discover that the field and scope of the
science cannot be thus rigidly limited to purely physical prob-
lems. The study of the physical development of the earth
throughout past ages brings us at once in contact with the
forms of animal and vegetable life which peopled its surface in
bygone epochs, and it is found impossible adequately to com-

*y * Gr. gf, the earth ; logos, a discourse.

2 PRINCIPLES OF PALEONTOLOGY.

prebend the former, unless we possess some knowledge of the
latter. However great its physical advantages may be, Geology
remains imperfect till it is wedded with Palaeontology,* a study
which essentially belongs to the vast complex of the Biologi-
cal Sciences, but at the same time has its strictly geological
side. Dealing, as it does, wholly with the consideration of
such living beings as do not belong exclusively to the present
order of things, Palaeontology is, in reality, a branch of Natu-
ral History, and may be regarded as substantially the Zoology
and Botany of the past. It is the ancient life-history of the
earth, as revealed to .us by the labors of palaeontologists, with
which we have mainly to do here; but before entering upon
this, there are some general questions, affecting Geology and
Palaeontology alike, which may be very briefly discussed.

The working geologist, dealing in the main with purely phys-
ical problems, has for his object to determine the material
structure of the earth, and to investigate, as far as may be, the
long chain of causes of which that structure is the ultimate re-
sult. No wider or more extended field of inquiry could be
found; but philosophical geology is not content with this. At
all the confines of his science, the transcendental geologist
finds himself confronted with some of the most stupendous
problems which have ever engaged the restless intellect of hu-
manity. The origin and primaeval constitution of the terrestrial
globe, the laws and geologic action through long ages of vicis-
situde and development, the origin of life, the nature and source
of the myriad complexities of living beings, the advent of man,
possibly even the future history of the earth, are amongst the
questions with which the geologist has to grapple in his higher
capacity.

These are problems which have occupied the attention of
philosophers in every age of the world, and in periods long
antecedent to the existence of a science of geology. The mere
existence of cosmogonies in the religion of almost every nation,
both ancient and modern, is a sufficient proof of the eager de-
sire of the human mind to know something of the origin of the
earth on which we tread. Every human being who has gazed
on the vast panorama of the universe, though it may have been
but with the eyes of a child, has felt the longing to solve, how-
ever imperfectly, "the riddle of the painful earth," and has,
consciously or unconsciously, elaborated some sort of a theory
as to the why and wherefore of what he sees. Apart from the
* Gr. palaios, ancient ; onto, beings ; logos, discourse.

THE LAWS OF GEOLOGICAL ACTION. 3

profound and perhaps inscrutable problems which lie at the
bottom of human existence, men have in all ages invented
theories to explain the common phenomena of the material uni-
verse; and most of these theories, however varied in their de-
tails, turn out on examination to have a common root, and to
be based on the same elements. Modern geology has its own
theories on the same subject, and it will be well to glance for
a moment at the principles underlying the old and the new
views.

It has been maintained, as a metaphysical hypothesis, that
there exists in the mind of man an inherent principle, in virtue
of which he believes and expects that what has been, will be;
and that the course of nature will be a continuous and unin-
terrupted one. So far, however, from any such belief existing
as a necessary consequence of the constitution of the human
mind, the real fact seems to be that the contrary belief has
been almost universally prevalent. In all old religions, and in
the philosophical systems of almost all ancient nations, the order
of the universe has been regarded as distinctly unstable, mu-
table, and temporary. A beginning and an end have always
been assumed, and the course of terrestrial events between these
two indefinite points has been regarded as liable to constant
interruption by revolutions and catastrophes of different kinds,
in many cases emanating from supernatural sources. Few of
the more ancient theological creeds, and still fewer of the
ancient philosophies, attained body and shape without contain-
ing, in some form or other, the belief in the existence of peri-
odical convulsions, and of alternating cycles of destruction and
repair.

That geology, in its early infancy, should have become im-
bued with the spirit of this belief, is no more than might have
been expected; and hence arose the at one time powerful and
generally-accepted doctrine of " Catastrophism." That the suc-
cession of phenomena upon the globe, whereby the earth's crust
had assumed the configuration and composition which we find
it to possess, had been a discontinuous and broken succession,
was the almost inevitable conclusion of the older geologists.
Everywhere in their study of the rocks they met with appar-
ently impassable gaps, and breaches of continuity that could
not be bridged over. Everywhere they found themselves con-
ducted abruptly from one system of deposits to others totally
different in mineral character or in stratigraphical position.
Everywhere they discovered that well-marked and easily recog-

4 PRINCIPLES OF PALAEONTOLOGY.

nizable groups of animals and plants were succeeded, without
the intermediation of any obvious lapse of time, by other assem-
blages of organic beings of a different character. Everywhere
they found evidence that the earth's crust had undergone changes
of such magnitude as to render it seemingly irrational to sup-
pose that they could have been produced by any process now in
existence. If we add to the above the prevalent belief of the
time as to the comparative brevity of the period which had
elapsed since the birth of the globe, we can readily understand
the general acceptance of some form of catastrophism amongst
the earlier geologists.

As regards its general sense and substance, the doctrine of
catastrophism held that the history of the earth, since first it
emerged from the primitive chaos, had been one of periods of
repose, alternating with catastrophes and cataclysms of a more
or less violent character. The periods of tranquillity were sup-
posed to have been long and protracted ; and during each of
them it was thought that one of the great geological " forma-
tions " was deposited. In each of these periods, therefore, the
condition of the earth was supposed to be much the same as it
is now — sediment was quietly accumulated at the bottom of the
sea, and animals and plants flourished uninterruptedly and in
successive generations. Each period of tranquillity, however, was
believed to have been, sooner or later, put an end to by a sud-
den and awful convulsion of nature, ushering in a brief and
paroxysmal period, in which the great physical forces were
unchained and permitted to spring into a portentous activity.
The forces of subterranean fire, with their concomitant phe-
nomena of earthquake and volcano, were chiefly relied upon as
the efficient cause of these periods of spasm and revolution.
Enormous elevations of portions of the earth's crust were thus
believed to be produced, accompanied by corresponding and
equally gigantic depressions of other portions. In this way new
ranges of mountains were produced, and previously existing
ranges levelled with the ground, seas were converted into dry
land, and continents buried beneath the ocean — catastrophe fol-
lowing catastrophe, till the earth was rendered uninhabitable,
and its races of animals and plants were extinguished, never to
reappear in the same form. Finally, it was believed that this
feverish activity ultimately died out, and that the ancient peace:
once more came to reign upon the earth. As the abnormal
throes and convulsions began to be relieved, the dry land and
sea once more resumed their relations of stability, the condi-

THE LAWS OF GEOLOGICAL ACTION. 5

tions of life were once more established, and new races of ani-
mals and plants sprang into existence, to last until the super-
vention of another fever-fit.

Such is the past history of the globe, as sketched for us, in
alternating scenes of fruitful peace and revolutionary destruc-
tion, by the earlier geologists. As before said, we cannot won-
der at the former general acceptance of Catastrophistic doc-
trines. Even in the light of our present widely-increased
knowledge, the series of geological monuments remains a broken
and imperfect one; nor can we ever hope to fill up completely
the numerous gaps with which the geological record is defaced.
Catastrophism was the natural method of accounting for these
gaps, and, as we shall see, it possesses a basis of truth. At pres-
ent, however, catastrophism may be said to be nearly extinct, and
its place is taken by the modern doctrine of "Continuity" or
" Uniformity " — a doctrine with which the name of Lyell must
ever remain imperishably associated.

The fundamental thesis of the doctrine of Uniformity is,
that, in spite of all apparent violations of continuity, the se-
quence of geological phenomena has in reality been a regular
and uninterrupted one; and that the vast changes which can be
shown to have passed over the earth in former periods have
been the result of the slow and ceaseless working of the ordi-
nary physical forces — acting with no greater intensity than they
do now, but acting through enormously prolonged periods. The
essential element in the theory of Continuity is to be found in
the allotment of indefinite time for the accomplishment of the
known series of geological changes. It is obviously the case,
namely, that there are two possible explanations of all phenom-
ena which lie so far concealed in "the dark backward and
abysm of time," that we can have no direct knowledge of the
manner in which they were produced. We may, on the one
hand, suppose them to be the result of some very powerful cause,
acting through a short period of time. That is Catastrophism.
Or, we may suppose them to be caused by a much weaker force
operating through 3 proportionately prolonged period. This is
the view of the Uniformitarians. It is a question of energy
versus time; and it is time which is the true element of the case.
An earthquake may remove a mountain in the course of a few
seconds; but the dropping of the gentle rain will do the same,
if we extend its operations over a millennium. And this is true
of all agencies which are now at work, or ever have been at
work, upon our planet. The Catastrophists, believing that the

6 PRINCIPLES OF PALAEONTOLOGY.

globe is but, as it were, the birth of yesterday, were driven of
necessity to the conclusion that its history had been checkered
by the intermittent action of paroxysmal and almost inconceiva-
bly potent forces. The Uniformitarians, on the other hand,
maintaining the " adequacy of existing causes," and denying that
the known physical forces ever acted in past time with greater
intensity than they do at present, are, equally of necessity, driven
to the conclusion that the world is truly in its " hoary eld," and
that its present state is really the result of the tranquil and
regulated action of known forces through unnumbered and in-
numerable centuries.

The most important point for us, in the present connection,
is the bearing of these opposing doctrines upon the question as
to the origin of the existing terrestrial order. On any doctrine
of uniformity that order has been evolved slowly, and, accord-
ing to law, from a pre-existing order. Any doctrine of catas-
trophism, on the other hand, carries with it, by implication, the
belief that the present order of things was brought about sud-
denly and irrespective of any pre-existent order; and it is
important to hold clear ideas as to which of these beliefs is the
true one. In the first place, we may postulate that the world
had a beginning, and, equally, that the existing terrestrial order
had a beginning. However far back we may go, geology does
not, and cannot, reach the actual beginning of the world; and
we are, therefore, left simply to our own speculations on this
point. With regard, however, to the existing terrestrial order,
a great deal can be discovered, and to do so is one of the prin-
cipal tasks of geological science. The first steps in the produc-
tion of that order lie buried in the profound and unsearchable
depths of a past so prolonged as to present itself to our finite
minds as almost an eternity. The last steps are in the prophetic
future, and can be but dimly guessed at. Between the remote
past and the distant future, we have, however, a long period
which is fairly open to inspection ; and in saying a " long "
period, it is to be borne in mind that this term is used in its
geological sense. Within this period, enormously long as it is
when measured by human standards, we can trace with reason-
able certainty the progressive march of events, and can deter-
mine the laws of geological action, by which the present order
of things has been brought about.

The natural belief on this subject doubtless is, that the
world, such as we now see it, possessed its present form and
configuration from the beginning. Nothing can be more nat-

THE LAWS OF GEOLOGICAL ACTION. 7

ural than the belief that the present continents and oceans have
always been where they are now ; that we have always had the
same mountains and plains; that our rivers have always had
their present courses, and our lakes their present positions, that
our climate has always been the same; and that our animals
and plants have always been identical with tnose now familiar
to us. Nothing could be more natural than such a belief, and
nothing could be further removed from the actual truth. On
the contrary, a very slight acquaintance with geology shows us,
in the words of Sir John Herschel, that "the actual configura-
tion of our continents and islands, the coast-lines of our maps,
the direction and elevation of our mountain-chains, the courses
of our rivers, and the soundings of our oceans, are not things
primordially arranged in the construction of our globe, but re-
sults of successive and complex actions on a former state of
things; that, again, of similar actions on another still more re-
mote: and so on, till the original and really permanent state is
pushed altogether out of sight and beyond the reach even of
imagination ; while on the other hand, a similar, and, as far as
we can see, interminable vista is opened out for the future, by
which the habitability of our planet is secured amid the total
abolition on it of the present theatres of terrestrial life."

Geology, then, teaches us that the physical features which
now distinguish the earth's surface have been produced as the
ultimate result of an almost endless succession of precedent
changes. Palaeontology teaches us, though not yet in such as-
sured accents, the same lesson. Our present animals and plants
have not been produced, in their innumerable forms, each as we
now know it, as the sudden, collective, and simultaneous birth
of a renovated world. On the contrary, we have the clearest
evidence that some of our existing animals and plants made
their appearance upon the earth at a much earlier period than
others. In the confederation of animated nature some races
can boast of an immemorial antiquity, whilst others are com-
parative parvenus. We have also the clearest evidence that the
animals and plants which now inhabit the globe have been pre-
ceded, over and over again, by other different assemblages of
animals and plants, which have flourished in successive periods
of the earth's history, have reached their culmination, and then
have given way to a fresh series of living beings. We have,
finally, the clearest evidence that these successive groups of
animals and plants (faunae and florae) are to a greater or less
extent directly connected with one another. Each group is, to

8 PRINCIPLES OF PALEONTOLOGY.

a greater or less extent, the lineal descendant of the group which
immediately preceded it in point of time, and is more or less
fully concerned with giving origin to the group which immedi-
ately follows it. That this law of " evolution " has prevailed
to a great extent is quite certain ; but it does not meet all the
exigencies of the case, and it is probable that its action has been
supplemented by some still unknown law of a different character.

We shall have to consider the question of geological "con-
tinuity" again. In the meanwhile, it is sufficient to state that
this doctrine is now almost universally accepted as the basis of
all inquiries, both in the domain of geology and that of palaeon-
tology. The advocates of continuity possess one of immense
advantage over those who believe in violent and revolutionary
convulsions, that they call into play only agencies of which we
have actual knowledge. We know that certain forces are now
at work, producing certain modifications in the present condi-
tion of the globe ; and we know that these forces are capable of
producing the vastest of the changes which geology brings under
our consideration, provided we assign a time proportionately
vast for their operation. On the other hand, the advocates of
catastrophism, to make good their views, are compelled to invoke
forces and actions, both destructive and restorative, of which we
have, and can have, no direct knowledge. They endow the
whirlwind and the earthquake, the central fire and the rain from
heaven, with powers as mighty as ever imagined in fable, and
they build up the fragments of a repeatedly shattered world by
the intervention of an intermittently active creative power.

It should not be forgotten, however, that from one point of
view there is a truth in catastrophism which is sometimes over-
looked by the advocates of continuity and uniformity. Catas-
trophism has, as its essential feature, the proposition that the
known and existing forces of the earth at one time acted with
much greater intensity and violence than they do at present,
and they carry down the period of this excessive action to the
commencement of the present terrestrial order. The Uniformi-
tarians, in effect, deny this proposition, at any rate as regards
any period of the earth's history of which we have actual cog-
nizance. If, however, the " nebular hypothesis " of the origin
of the universe be well founded — as is generally admitted — then,
beyond question, the earth is a gradually cooling body, which
has at one time been very much hotter than it is at present.
There has been a time, therefore, in which the igneous forces of
the earth, to which we owe the phenomena of earthquakes and

THE LAWS OF GEOLOGICAL ACTION. 9

volcanoes, must have been far more intensely active than we
can conceive of from anything that we can see at the present
day. By the same hypothesis, the sun is a cooling body, and
must have at one time possessed a much higher temperature
than it has at present. But increased heat of the sun would
seriously alter the existing conditions affecting the evaporation
and precipitation of moisture on our earth; and hence the
aqueous forces may also have acted at one time more power-
fully than they do now. The fundamental principle of catas-
trophism is, therefore, not wholly vicious; and we have reason
to think that there must have been periods — very remote, it ^s
true, and perhaps unrecorded in the history of the earth — in
which the known physical forces may have acted with an inten-
sity much greater than direct observation would lead us to
imagine. And this may be believed, altogether irrespective of
those great secular changes by which hot or cold epochs are
produced, and which can hardly be called " catastrophistic," as
they are produced gradually, and are liable to recur at definite
intervals.

Admitting, then, that there is a truth at the bottom of the
once current doctrines of catastrophism, still it remains certain
that the history of the earth has been one of law in all past time,
as it is now. Nor need we shrink back affrighted at the vast-
ness of the conception — the vaster for its very vagueness — that
we are thus compelled to form as to the duration of geological
time. As we grope our way backward through the dark laby-
rinth of the ages, epoch succeeds to epoch, and period to period,
each looming more gigantic in its outlines and more shadowy
in its features, as it rises, dimly revealed, from the mist and
vapor of an older and ever-older past. It is useless to add
century to century or millennium to millennium. When we pass
a certain boundary-line, which, after all, is reached very soon,
figures cease to convey to our finite faculties any real notion of
the periods with which we have to deal. The astronomer can
employ material illustrations to give form and substance to our
conceptions of celestial space; but such a resource is unavail-
able to the geologist. The few thousand years of which we have
historical evidence sink into absolute insignificance besides the
unnnumbered aeons which unroll themselves one by one as we
penetrate the dim recesses of the past, and decipher with feeble
vision the ponderous volumes in which the record of the earth
is written. Vainly does the strained intellect seek to overtake
an ever-receding commencement, and toil to gain some adequate

io PRINCIPLES OF PALEONTOLOGY.

grasp of an apparently endless succession. A beginning there
must have been, though we can never hope to fix its point. Even
speculation droops her wings in the attenuated atmosphere of a
past so remote, and the light of imagination is quenched in the
darkness of a history so ancient. In time, as in space, the con-
fines of the universe must ever remain concealed from us; and
of the end we know no more than of the beginning. Inconceiv-
able as is to us the lapse of " geological time," it is no more than
"a mere moment of the past, a mere infinitesimal portion of
eternity." Well may " the human heart, that weeps and trem-
bles," say, with Richter's pilgrim through celestial space, " I will
go no farther; for the spirit of man acheth with this infinity.
Insufferable is the glory of God. Let me lie down in the grave,
and hide me from the persecution of the Infinite, for end, I
see, there is none. "

CHAPTER I.
THE SCOPE AND MATERIALS OF PALAEONTOLOGY.

The study of the rock-masses which constitute the crust of
the earth, if carried out in the methodical and scientific manner
of the geologist, at once brings us, as has been before remarked,
in contact with the remains or traces of living beings which
formerly dwelt upon the globe. Such remains are found, in
greater or less abundance, in the great majority of rocks; and
they are not only of great interest in themselves, but they have
proved of the greatest importance as throwing light upon vari-
ous difficult problems in geology, in natural history, in botany,
and in philosophy. Their study constitutes the science of palaeon-
tology; and though it is possible to proceed to a certain length
in geology and zoology without much palaeontological knowledge,
it is hardly possible to attain to a satisfactory general acquaint-
ance with either of these subjects without having mastered the
leading facts of the first. Similarly, it is not possible to study
palaeontology without some acquaintance with both geology and
natural history.

PALAEONTOLOGY, then, is the science which treats of the liv-
ing beings, whether animal or vegetable, which have inhabited

THE SCOPE OF PALEONTOLOGY. n

the earth during past periods of its history. Its object is to
eludicate, as far as may be, the structure, mode of existence,
and habits of all such ancient forms of life; to determine their
position in the scale of organized beings ; to lay down the geo-
graphical limits within which they flourished; and to fix the
period of their advent and disappearance. It is the ancient life-
history of the earth; and were its record complete, it would
furnish us with a detailed knowledge of the form and relations
of all the animals and plants which have at any period flourished
upon the land-surfaces of the globe or inhabited its waters ; it
would enable us to determine precisely their succession in time;
and it would place in our hands an unfailing key to the prob-
lems of evolution. Unfortunately, from causes which will be
subsequently discussed, the palaeontological record is extremely
imperfect, and our knowledge is interrupted by gaps, which not
only bear a large proportion to our solid information, but which
in many cases are of such a nature that we can never hope to
fill them up

FOSSILS. — The remains of animals or vegetables which we
now find entombed in the solid rock, and which constitute the
working material of the palaeontologist, are termed " fossils, " *
or " petrifactions. " In most cases, as can be readily understood,
fossils are the actual hard parts of animals and plants which
were in existence when the rock in which they are now found
was being deposited. Most fossils, therefore, are of the nature
of the shells of shell-fish, the skeletons of coral-zoophytes, the
bones of vertebrate animals, or the wood, bark, or leaves of
plants. All such bodies are more or less of a hard consistence
to begin with, and are capable of resisting decay for a longer or
shorter time — hence the frequency with which they occur in the
fossil condition. Strictly speaking, however, by the term " fossil "
must be understood " any body, or the traces of the existence of
any body, whether animal or vegetable, which has been buried
in the earth by natural causes" (Lyell). We shall find, in fact,
that many of the objects which we have to study as "fossils"
have never themselves actually formed parts of any animal or
vegetable, though they are due to the former existence of such
organisms, and indicate what was the nature of these. Thus
the footprints left by birds, or reptiles, or quadrupeds upon sand
or mud, are just as much proofs of the former existence of
these animals as would be bones, feathers, or scales, though in

* Lat. fossus, dug up.

12 PRINCIPLES OF PALAEONTOLOGY.

themselves they are inorganic. Under the head of fossils, there-
fore, come the footprints of air-breathing vertebrate animals;
the tracks, trails, and burrows of sea-worms, crustaceans, or
molluscs; the impressions left on the sand by stranded jelly-
fishes ; the burrows in stone or wood of certain shell-fish ; the
" moulds " or " casts " of shells, corals, and other organic re-
mains ; and various other bodies of a more or less similar nature.

FOSSILIZATION. — The term " fossilization " is applied to all
those processes through which the remains of organized beings
may pass in being converted into fossils. These processes are
numerous and varied; but there are three principal modes of
fossilization which alone need be considered here. In the first
instance, the fossil is to all intents and purposes an actual por-
tion of the original organized being — such as a bone, a shell, or
a piece of wood. In some rare instances, as in the case of the
body of the Mammoth discovered embedded in ice at the mouth
of the Lena in Siberia, the fossil may be preserved almost pre-
cisely in its original condition, and even with its soft parts un-
injured. More commonly, certain changes have taken place in
the fossil, the principal being the more or less removal of the
organic matter originally present. Thus bones become light and
porous by the removal of their gelantine, so as to cleave to the
tongue on being applied to that organ; whilst shells become
fragile, and lose their primitive colors. In other cases, though
practically the real body it represents, all the cavities of the
fossil, down to its minutest recesses, may have become infiltrated
with mineral matter. It need hardly be added, that it is in the
more modern rocks that we find the fossils, as a rule, least
changed from their former condition; but the original structure
is often more or less completely retained in some of the fossils
from even the most ancient formations.

In the second place, we very frequently meet with fossils in
the state of "casts" or moulds of the original organic body.
What occurs in this case will be readily understood if we imag-
ine any common bivalve shell, as an Oyster, or Mussel, or
Cockle, embedded in clay or mud. If the clay were sufficiently
soft and fluid, the first thing would be that it would gain access
to the interior of the shell, and would completely fill up the
space between the valves. The pressure, also, of the surround-
ing matter would insure that the clay would everywhere ad-
here closely to the exterior of the shell. If now we suppose the
clay to be in any way hardened so as to be converted into
stone, and if we were to break up the stone, we should obviously

THE SCOPE OF PALEONTOLOGY. 13

have the following state of parts. The clay which filled the
shell would form an accurate cast of the interior of the shell,
and the clay outside would give us an exact impression or
cast of the exterior of the shell (fig. i). We should have, then,

two casts, an interior and an
exterior, and the two would
be very different to one another,
since the inside of a shell is
very unlike the outside. In
the case, in fact, of many uni-
valve shells, the interior cast or
" mould " is so unlike the ex-
terior cast, or unlike the shell
Fig. i.—Triffonia longa, showing casts itself, that it may be difficult to

determine the true origin of the
former.

It only remains to add that there is sometimes a further
complication. If the rock be very porous and permeable by
water, it may happen that the original shell is entirely dissolved
away, leaving the interior cast loose, like the kernel of a nut,
within the case formed by the exterior cast. Or it may happen
that subsequent to the attainment of this state of things, the
space thus left vacant between the interior and exterior cast —
the space, that is, formerly occupied by the shell itself — may be
filled up by some foreign mineral deposited there by the infil-
tration of water. In this last case the splitting open of the
rock would reveal an interior cast, an exterior cast, and finally
a body which would have the exact form of the original shell,
but which would be really a much later formation, and which
would not exhibit under the microscope the minute structure of
shell.

In the third class of cases we have fossils which present
with the greatest accuracy the external form, and even some-
times the internal minute structure, of the original organic body,
but which, nevertheless, are not themselves truly organic, but
have been formed by a " replacement " of the particles of the
primitive organism by some material substance. The most ele-
gant example of this is afforded by fossil wood which has been
"silicified" or converted into flint (silex}. ^n such cases we
have fossil wood which presents the rings of growth and fibrous
structure of recent wood, and which under the microscope
exhibits the minutest vessels which characterize ligneous tissue,
together with the even more minute markings of the vessels

U PRINCIPLES OF PALEONTOLOGY.

(fig. 2.) The whole, however, instead of being composed
of the original carbonaceous matter of wood, is now converted
into flint. The only explanation that can be given of this by no
means rare phenomenon, is that the wood must have undergone
a slow process of decay in water charged with silica or flint in
solution. As each successive particle of wood was removed

Fig, 2. —Microscopic section of the
silicified wood of a Conifer (Sequoia} cut
in the long direction of the fibres. Post-
tertiary? Colorado. (Original.)

Fig. 3.— Microscopic section of the wood
of the common Larch (Abies larix), cut
in the long direction of the fibres. In
both the fresh and the fossil wood (fig.
2) are seen the discs characteristic of con-
iferous wood. (Original.)

by decay, its place was taken by a particle of flint deposited
from the surrounding water, till ultimately the entire wood was
silicified. The process, therefore, resembles what would take
place if we were to pull down a house built of brick by succes-
sive bricks, replacing each brick as removed by a piece of stone
of precisely the same size and form. The result of this would
be that the house would retain its primitive size, shape, and out-
line, but it would finally have been converted from a house of
brick into a house of stone. Many other fossils besides wood —
such as shells, corals, sponges, &c. — are often found silicified;
and this may be regarded as the commonest form of fossiliza-
tion by replacement. In other cases, however, though the prin-
ciple of the process is the same, the replacing substance may be
iron pyrites, oxide of iron, sulphur, malachite, magnesite, talc,
&c. ; but it is rarely that the replacement with these minerals is
so perfect as to preserve the more delicate details of internal
structure.

CHAPTER II.

THE FOSSILIFEROUS ROCKS.

Fossils are found in rocks, though not universally or pro-
miscuously ; and it is therefore necessary that the palaeonto-
logist should possess some acquaintance with, at any rate, those
rocks which yield organic remains, and which are therefore
said to be " fossiliferous. " In geological language, all the ma-
terials which enter into the composition of the solid crust of
the earth, be their texture what it may — from the most impal-
pable mud to the hardest granite — are termed "rocks;" and for
our present purpose we may divide these into two great groups.
In the first division are the Igneous Rocks — such as the lavas and
ashes of volcanoes — which are formed within the body of the
earth itself, and which owe their structure and origin to the
action of heat. The Igneous Rocks are formed primarily below
the surface of the earth, which they only reach as the result of
volcanic action; they are generally destitute of distinct "strati-
fication," or arrangement in successive layers ; and they do
not contain fossils, except in the comparatively rare instances
where volcanic ashes have enveloped animals or plants which
were living in the sea or on the land in the immediate vicinity
of the volcanic focus. The second great division of rocks is
that of the Fossiliferous, Aqueous, or Sedimentary Rocks. These
are formed at the surface of the earth, and, as implied by one
of their names, are invariably deposited in water. They are
produced by vital or chemical action, or are formed from the
" sediment " produced by the disintegration and reconstruction
of previously existing rocks, without previous solution ; they
mostly contain fossils ; and they are arranged in distinct layers
or " strata." The so-called " aerial " rocks which, like the beds
of blown sand, have been formed by the action of the atmos-
phere, may also contain fossils; but they are not of such im-
portance as to require special notice here.

15

i6

PRINCIPLES OF PALEONTOLOGY.

For all practical purposes, we may consider that the Aque-
ous Rocks are the natural cemetery of the animals and plants
of bygone ages; arid it is therefore essential that the palaeonto-

Fi«r. 4.— Sketch of Carboniferous strata at Kinghorn, in Fife, showing stratified beds
(limestone and shales) surmounted by an unstratified mass of trap. (Original).

logical student should be acquainted with some of the principal
facts as to their physical characters, their minute structure
and mode of origin, their chief varieties, and their historical
succession.

The Sedimentary or Fossiliferous Rocks form the greater
portion of that part of the earth's crust which is open to our
examination, and are distinguished by the fact that they are
regularly " stratified " or arranged in distinct and definite layers
or " strata." These layers may consist of a single material, as
in a block of sandstone, or they may consist of different ma-
terials. When examined on a large scale, they are always found
to consist of alternations of layers of different mineral com-
position. We may examine any given area, and find in it noth-
ing but one kind of rock — sandstone, perhaps, or limestone.

THE FOSSILIFEROUS ROCKS. 17

In all cases, however, if we extend our examination sufficiently
far, we shall ultimately come upon different rocks ; and, as
a general rule, the thickness of any particular set of beds is
comparatively small, so that different kinds of rock alternate
with one another in comparatively small spaces.

As regards the origin of the Sedimentary Rocks, they are
for the most part " derivative " rocks, being derived from the
wear and tear of pre-existent rocks. Sometimes, however, they
owe their origin to chemical or vital action, when they would
more properly be spoken of simply as Aqueous Rocks. As to
their mode of deposition, we are enabled to infer that the mate-
rials which compose them have formerly been spread out by
the action of water, from what we see going on every day at
the mouths of our great rivers, and on a smaller scale wherever
there is running water. Every stream, where it runs into a
lake or into the sea, carries with it a burden of mud, sand, and
rounded pebbles, derived from the waste of the rocks which

ft

Fig. 5.— Diagram to illustrate the formation of sedimentary deposits at the point
where a river debouches into the sea.

form its bed and banks. When these materials cease to be im-
pelled by the force of the moving water, they sink to the bot-
tom, the heaviest pebbles, of course, sinking first, the smaller

i8 PRINCIPLES OF PALEONTOLOGY.

pebbles and sand next, and the finest mud last. Ultimately,
therefore, as might have been inferred upon theoretical grounds
and as is proved by practical experience, every lake becomes a
receptacle for a series of stratified rocks produced by the streams
flowing into it. These deposits may vary in different parts of
the lake, according as one stream brought down one kind of
material and another stream contributed another material ; but
in all cases the materials will bear ample evidence that they were
produced, sorted, and deposited by running water. The finer
beds of clay or sand will all be arranged in thicker or thinner
layers or laminae; and if there are any beds of pebbles these
will all be rounded or smooth, just like the water-worn pebbles
of any brook-course. In all probability, also, we should find in
some of the beds the remains of fresh-water shells or plants or
other organisms which inhabited the lake at the time these beds
were being deposited.

In the same way large rivers — such as the Ganges or
Mississippi — deposit all the materials which they bring down at
their mouths, forming in this way their " deltas. " Whenever
such a delta is cut through, either by man or by some channel of
the river altering its course, we find that it is composed of a suc-
cession of horizontal layers or strata of sand or mud, varying in
mineral composition, in structure, or in grain, according to the
nature of the material brought down by the river at different
periods. Such deltas, also, will contain the remains of animals
which inhabit the river, with fragments of the plants which
grew on its banks, or bones of the animals which lived in its
basin.

Nor is this action confined, of course, to large rivers only,
though naturally most conspicuous in the greatest bodies of
water. On the contrary, all streams, of whatever size are
engaged in the work of wearing down the dry land, and of
transporting the materials thus derived from higher to lower
levels, never resting in this work till they reach the sea.

Lastly, the sea itself — irrespective of the materials delivered
into it by rivers — is constantly preparing fresh stratified deposits
by its own action. Upon every coast-line the sea is constantly
eating back into the land and reducing its component rocks to
form the shingle and sand which we see upon every shore.
The materials thus produced are not, however, lost, but are
ultimately deposited elsewhere in the form of new stratified
accumulations, in which are buried the remains of animals
inhabiting the sea at the time.

THE FOSSILIFEROUS ROCKS. 19

\Yhenever, then, we find anywhere in the interior of the
land any series of beds having these characters — composed, that
is, of distinct layers, the particles of which, both large and small,
show distinct traces of the wearing action of water — whenever
and wherever we find such rocks, we are justified in assuming
that they have been deposited by water in the manner above
mentioned. Either they were laid down in some former lake
by the combined action of the streams which flowed into it ;
or they were deposited at the mouth of some ancient river,
forming its delta ; or they were laid down at the bottom of the
ocean. In the first two cases, any fossils which the beds might
contain would be the remains of fresh-water or terrestrial organ-
isms. In the last case, the majority, at any rate, of the fossils
would be the remains of marine animals.

The term " formation " is employed by geologists to express
" any group of rocks which have some character in common,
whether of origin, age, or composition " (Lyell) ; so that we
may speak of stratified and unstratified formations, aqueous
or igneous formations, fresh-water or marine formations, and
so on.

CHIEF DIVISIONS OF THE AQUEOUS ROCKS.

The Aqueous Rocks may be divided into two great sections,
the Mechanically-formed and the Chemically-formed, includ-
ing under the last head all rocks which owe their origin to
vital action, as well as those produced by ordinary chemical
agencies.

A. MECHANICALLY-FORMED ROCKS. — These are all those
Aqueous Rocks of which we can obtain proofs that their particles
have been mechanically transported to their present situation.
Thus, if we examine a piece of conglomerate or puddingstone,
we find it to be composed of a number of rounded pebbles em-
bedded in an enveloping matrix or paste, which is usually of a
sandy nature, but may be composed of carbonate of lime (when
the rock is said to be "Calcareous conglomerate"). The peb-
bles in all conglomerates are worn and rounded by the action of
water in motion, and thus show that they have been subjected
to much mechanical attrition whilst they have been mechanically
transported for a greater or less distance from the rock of
which they originally formed part. The analogue of the old con-
glomerates at the present day is to be found in the great beds

20 PRINCIPLES OF PALEONTOLOGY.

of shingle and gravel which are formed by the action of the sea
on every coast-line, and which are composed of water-worn and
well-rounded pebbles of different sizes. A breccia is a mechan-
ically-formed rock, very similar to a conglomerate, and consisting
of larger or smaller fragments of rock embedded in a common
matrix. The fragments, however, are in this case all more or
less angular, and are not worn or rounded. The fragments in
breccias may be of large size, or they may be comparatively
small (fig. 6) ; and the matrix may be composed of sand (are-
naceous) or of carbonate of
lime (calcareous). In the case
of an ordinary sandstone,
again, we have a rock which
may be regarded as simply a
very fine-grained conglomerate
or breccia, being composed of
small grains of sand (silica),
sometimes rounded, sometimes
more or less angular, cemented
together by some such sub-
stance as oxide of iron, silicate
of iron, or carbonate of lime.
A sandstone, therefore, like a Fig. 6. -Microscopic section of a calcare-
conglomerate, is a mechanic- °us breccia in the Lower Silurian (Coniston
. Limestone) of Snap Wells, Westmoreland.

ally- formed rock, Its COmpO- The fragments are all of small size, and

npnt o-rainc hpincr Pnnallv thp consist of angular pieces of transparent

,ing equally 1 e quartz, volcanic ashes, and limestone em-

resillt of mechanical attrition bedded in a matrix of crystalline limestone.

, . (Original.)

and having equally been trans-
ported from a distance ; and the same is true of the ordinary
sand of 'the sea-shore, which is nothing more than an uncon-
solidated sandstone. Other so-called sands and sandstones,
though equally mechanical in their origin, are truly calcareous
in their nature, and are more or less entirely composed of
carbonate of lime. Of this kind are the shell-sand so common
on our coast?, and the coral-sand which is so largely formed in
the neighborhood of coral-reefs. In these cases the rock is com-
posed of fragments of the skeletons of shell-fish and numerous
other marine animals, together, in many instances, with the
remains of certain sea-weeds (Corallines, Nullipores, &c.) which
are endowed with the power of secreting carbonate of lime from
the sea-water. Lastly, in certain rocks still finer in their texture
than sandstones, such as the various mud-rocks and shales, we
can still recognize a mechanical source and origin. If slices of

THE FOSSILIFEROUS ROCKS. 21

any of these rocks sufficiently thin to be transparent are
examined under the microscope, it will be found that they are
composed of minute grains of different sizes, which are all more
or less worn and rounded, and which clearly show, therefore,
that they have been subjected to mechanical attrition.

All the above-mentioned rocks, then, are mechanically-formed
rocks ; and they are often spoken of as " Derivative Rocks, "
in consequence of the fact that their particles can be shown to
have been mechanically derived from other pre-existent rocks.
It follows from this that every bed of any mechanically-formed
rock is the measure and equivalent of a corresponding amount
of destruction of some older rock. It is not necessary to enter
here into a minute account of the subdivisions of these rocks,
but it may be mentioned that they may be divided into two
principal groups, according to their chemical composition. In the
one group we have the so-called Arenaceous (Lat. arena, sand)
or Siliceous Rocks, which are essentially composed of larger or
smaller grains of flint or silica. In this group are comprised
ordinary sand, the varieties of sandstone and grit, and most
conglomerates and breccias. We shall, however, afterwards see
that some siliceous rocks are of organic origin. In fhe second group
are the so-called Argillaceous (Lat. argilla, clay) Rocks, which
contain a larger or smaller amount of clay or hydrated silicate of
alumina in their composition. Under this head come clays,
shales, marls, marl-slate, clay-slates, and most flags and flagstones.

B. CHEMICALLY-FORMED ROCKS. — In this section are com-
prised all those Aqueous or Sedimentary Rocks which have
been formed by chemical agencies. As many of these chemi-
cal agencies, however, are exerted through the medium of living
beings, whether animals or plants, we get into this section a
number of what may be called " organically-formed rocks. "
These are of the greatest possible importance to the palaeon-
tologist, as being to a greater or less extent composed of the
actual remains of animals or vegetables, and it will therefore be
necessary to consider their character and structure in some
detail.

By far the most important of the chemically-formed rocks
are the so-called Calcareous Rocks (Lat. calx, lime), com-
prising all those which contain a large proportion of carbonate of
lime, or are wholly composed of this substance. Carbonate
of lime is soluble in water holding a certain amount of car-
bonic acid gas in solution; and it is, therefore, found in larger
or smaller quantity dissolved in all natural waters, both fresh

22 PRINCIPLES OF PALAEONTOLOGY.

and salt, since these waters are always to some extent charged
with the above-mentioned solvent gas. A great number of
aquatic animals, however, together with some aquatic plants,
are endowed with the power of separating the lime thus held
in solution in the water, and of reducing it again to its solid
condition. In this way shell-fish, crustaceans, sea-urchins, corals,
and an immense number of other animals, are enabled to con-
struct their skeletons; whilst some plants form hard structures
within their tissues in a precisely similar manner. We do meet
with some calcareous deposits, such as the " stalactites " and
" stalagmites " of caves, the " calcareous tufa " and " travertine "
of some hot springs, and the spongy calcareous deposits of so-
called " petrifying springs, " which are purely chemical in their
origin, and owe nothing to the operation of living beings. Such
deposits are formed simply by the precipitation of carbonate of
lime from water, in consequence of the evaporation from the
water of the carbonic acid gas which formerly held the lime in
solution ; but, though sometimes forming masses of con-
siderable thickness and of geological importance, they do not
concern us here. Almost all the limestones which occur in the
series of the stratified rocks are, primarily at any rate, of organic
origin, and have been, directly or indirectly, produced by the
action of certain lime-making animals or plants, or both combined.
The presumption as to all the calcareous rocks, which cannot
be clearly shown to have been otherwise produced, is that they
are thus organically formed ; and in many cases this presump-
tion can be readily reduced to a certainty. There are many
varieties of the calcareous rocks, but the following are those
which are of the greatest importance : —

Chalk is a calcareous rock of a generally soft and pulver-
ulent texture, and with an earthy fracture. It varies in its
purity, being sometimes almost wholly composed of carbonate
of lime, and at other times more or less intermixed with foreign
matter. Though usually soft and readily reducible to powder,
chalk is occasionally, as in the north of Ireland, tolerably hard
and compact ; but it never assumes the crystalline aspect and
stony density of limestone, except it be in immediate contact with
some mass of igneous rock. By means of the microscope, the
true nature and mode of formation of chalk can be determined
with the greatest ease. In the case of the harder varieties, the
examination can be conducted by means of slices ground down
to a thinness sufficient to render them transparent; but in the
softer kinds the rock must be disintegrated under water, and the

THE FOSSILIFEROUS ROCKS.

debris examined microscopically. When investigated by either of
these methods, chalk is found to be a genuine organic rock, being
composed of the shells or hard parts of innumerable marine
animals of different kinds, some entire, some fragmentary,
cemented together by a matrix of very finely granular carbonate
of lime. Foremost amongst the animal remains which so largely
compose chalk are the shells of the minute creatures which will be
subsequently spoken of under the name of Foraminifera (fig. 7),

and which, in spite of their
microscopic dimensions, play a
more important part in the
process of lime-making than
perhaps any other of the larger
inhabitants of the ocean.

As chalk is found in beds
of hundreds of feet in thick-

examined by transmitted light and highly
magnified. Besides the entire shells of
Gflobigerina, Rotalia, and Textularia
of

ness, and of great purity, there
was long felt much difficulty
in satisfactorily accounting for
its mode of formation and ori-
gin. By the researches of
Carpenter, Wyville Thomson,
Fig. 7.-Section of Gravesend Chalk, Huxley, Wallich, and others,

it has, however, been shown

. ....

that there IS now forming, in

<he pr°f°und ****** ™

great oceans, a deposit which
is in all essential respects identical with chalk, and which is
generally known as the " Atlantic ooz, " from its having been
first discovered in that sea. This ooze is found at great
depths (5000 to over 15,000 feet) in both the Atlantic and
Pacific, covering enormously large areas of the sea-bottom,
and it presents itself as a whitish-brown, sticky, impalpable mud,
very like, greyish chalk when dried. Chemical examination
shows that the ooze is composed almost wholly of carbonate of
lime, and microscopical examination proves it to be of organic
origin, and to be made up of the remains of living beings.
The principal forms of these belong to the Foraminifera, and
the commonest of these are the irregularly-chambered shells of
Globigcrina, absolutely indistinguishable from the Globigerina:
which are so largely present in the chalk (fig. 8). Along with
these occur fragments of the skeletons of other larger creatures,
and a certain proportion of the flinty cases of minute animal and

PRINCIPLES OF PALAEONTOLOGY.

vegetable organisms (Polycystina and Diatoms). Though many
of the minute animals, the
hard parts of which form the
ooze, undoubtedly live at or
near the surface of the sea,
others, probably, really live
near the bottom; and the ooze
itself forms a congenial home
for numerous sponges, sea-
lilies, and other marine ani-
mals which flourish at great
depths in the sea. There is
thus established an intimate
and most interesting parallel-
ism between the chalk and
the ooze of modern oceans.

Fig. 8.— Organisms in the Atlantic Ooze,
chiefly Foraminlfera (Globigerinn and

Both are formed essentially in Textularia), with 1 >olycystina and sponge-
the same way, and the latter ^ules; highly magnified. (Original.)

only requires consolidation to become actually converted into
chalk. Both are fundamentally organic deposits, apparently
requiring a great depth of water for their accumulation, and
mainly composed of the remains of Foraminifera, together with
the entire or broken skeletons of other marine animals of greater
dimensions. It is to be remembered, however, that the ooze,
though strictly representative of the chalk, cannot be said in any
proper sense to be actuall}' identical with the formation so called
by geologists. A great lapse of time separates the two, and
though composed of the remains of representative classes or
groups of animals, it is only in the case of the lowly-organized
Globigerina, and of some other organisms of little higher grade,
that we find absolutely the same kinds or species of animals in
both.

Limestone, like chalk, is composed of carbonate of lime,
sometimes almost pure, but more commonly with a greater or
less intermixture of some foreign material, such as alumina or
silica. The varieties of limestone are almost innumerable, but
the great majority can be clearly proved to agree with chalk in
being essentially of organic origin, and in being more or less
largely composed of the remains of living beings. In many
instances the organic remains which compose limestone are so
large as to be readily visible to the naked eye, and the rock is
at once seen to be nothing more than an agglomeration of the
skeletons, generally fragmentary, of certain marine animals,

THE FOSSILIFEROUS ROCKS. 25

cemented together by matrix of carbonate of lime. This is the
case, for example, with the so-called " Crinoidal Limestones "
and " Encrinital Marbles " with which the geologist is so familiar,
especially as occurring in great beds amongst the older for-
mations of the earth's crust. These are seen, on weathered or
broken surfaces, or still better in polished slabs (fig. 9), to be com-

Fig. 9.— Slab of Crinoidal marble, from the Carboniferous limestone of Dent, In
Yorkshire, of the natural size. The polished surface intersects the columns of the
Crinolds at different angles, and thus gives rise to varying appearances. (Original.)

posed more or less exclusively of the broken stems and detached
plates of sea-lilies (Crinoids). Similarly, other limestones are
composed almost entirely of the skeletons of corals ; and such
old coralline limestones can readily be paralleled by formations
which we can find in actual course of production at the present
day. We only need to transport ourselves to the islands of the
Pacific, to the West Indies, or to the Indian Ocean, to find great
masses of lime formed similarly by living corals, and well known
to every one under the name of " coral-reefs. " Such reefs are
often of vast extent, both superficially and in vertical thickness,
and they fully equal in this respect any of the coralline lime-
stones of bygone ages. Again, we find other limestones — such
as the celebrated " Nummulitic Limestone" (fig. 10), which
sometimes attains a thickness of some thousands of feet — which
are almost entirely made up of the shells of Foraminifera. In
the case of the "Nummulitic Limestone," just mentioned, these

26 PRINCIPLES OF PALEONTOLOGY.

shells are of a large size, varying from the size of a split pea up
to that of a florin. There are, however, as we shall see, many
other limestones, which are likewise largely made up of

Fig. 10. — Piece of Nummulitlc Limestone from the Great Pyramid.
Of the natural size. (Original.)

Foraminifera, but in which the shells are very much more minute,
and would hardly be seen at all without the microscope.

We may, in fact, consider that the great agents in the pro-
duction of limestones in past ages have been animals belonging
to the Crinoids, the Corals, and the Foraminifera. At the pres-
ent day, the Crinoids have been nearly extinguished, and the
few known survivors seem to have retired to great depths in the
ocean; but the two latter still actively carry on the work of
lime-making, the former being very largely helped in their
operations by certain lime-producing marine plants (Nullipores
and Corallines}. We have to remember, however, that though
the limestones, both ancient and modern, that we have just
spoken of, are truly organic, they are not necessarily formed out
of the remains of animals which actually lived on the precise
spot where we now find the limestone itself. WTe may find a
crinoidal limestone, which we can show to have been actually
formed by the successive growth of generations of sea-lilies in
place; but we shall find many others in which the rock is made
up of innumerable fragments of the skeletons of these creatures,
which have been clearly worn and rubbed by the sea-waves, and
which have been mechanically transported to their present site.

THE FOSSILIFEROUS ROCKS. 27

In the same way, a limestone may be shown to have been an
actual coral-reef, by the fact that we find in it great masses of
coral, growing in their natural position, and exhibiting plain
proofs that they were simply quietly buried by the calcareous
sediment as they grew ; but other limestones may contain only
numerous rolled and water-worn fragments of corals. This is
precisely paralleled by what we can observe in our existing
coral-reefs. Parts of the modern coral-islands and coral-reefs
are really made up of corals, dead or alive, which actually grew
on the spot where we now find them; but other parts are com-
posed of limestone-rock ("coral-rock"), or of a loose and
("coral-sand"), which is organic in the sense that it is com-
posed of lime formed by living beings, but which, in truth, is
composed or fragments of the skeletons of these living beings,
mechanically transported and heaped together by the sea. To
take another example nearer home, we may find great accumu-
lations of calcareous matter formed in place, by the growth of
shell-fish, such as oysters or mussels ; but we can also find
equally great accumulations on many of our shores in the form
of " shell-sand " which is equally composed of the shells of mol-
luscs, but which is formed by the trituration of these shells by
the mechanical power of the sea-waves. We thus see that though
all these limestones are primarily organic, they not uncommonly
become " mechanically-formed " rocks in a secondary sense, the
materials of which they are composed being formed by living
beings, but having been mechanically transported to the place
where we now find them.

Many limestones, as we have seen, are composed of large
and conspicuous organic remains, such as strike the eye at once.
Many others, however, which at first sight appear compact, more
or less crystalline, and nearly devoid of traces of life, are found,
when properly examined, to be also composed of the remains of
various organisms. All the commoner limestones, in fact from
the Lower Silurian period onwards, can be easily proved to
be thus organic rocks, if we investigate weathered or polished sur-
faces with a lens, or, still better, if we cut thin slices of the rock
and grind these down till they are transparent. When thus ex-
amined, the rock is usually found to be composed of innumerable
entire or fragmentary fossils, cemented together by a granular
or crystalline matrix of carbonate of lime (figs. II and 12).
When the matrix is granular, the rock is precisely similar to
chalk, except that it is harder and less earthy in texture, whilst
the fossils are only occasionally referable to the Foraminifera.

28

PRINCIPLES OF PALEONTOLOGY,

In other cases, the matrix is more or less crystalline, and when
this crystallization has been carried to a great extent, the original
organic nature of the rock may be greatly or completely obscured
thereby. Thus, in limestones which have been greatly altered
or " metamorphosed " by the combined action of heat and pres-

Fig. 11. — Section of Carboniferous
Limestone from Spergen Hill, Indiana,
U. S., showing numerous large-sized
Foraminifera (Endothyra) and a few
oolitic grains ; magnified. (Original.)

Fig.12.— Section of Ccniston Limestone
(Lower Silurian) from Keisley, West-
moreland; magnified. The matrix is
very coarsely crystalline, and the in-
cluded organic remains are chiefly stems
of Crinoids. (Original.)

sure, all traces of organic remains become annihilated, and the
rock becomes completely crystalline throughout. This, for
example, is the case with the ordinary white " statuary marble, "
slices of which exhibit under the microscope nothing but an
aggregate of beautifully transparent crystals of carbonate of
lime, without the smallest traces of fossils. There are also other
cases, where the limestone is not necessarily high crystalline,
and where no metamorphic action in the strict sense has taken
place, in which, nevertheless, the microscope fails to reveal any
evidence that the rock is organic. Such cases are somewhat
obscure, and doubtless depend on different causes in different
instances ; but they do not affect the important generalization
that limestones are fundamentally the product of the operation
of living beings. This fact remains certain; and when we con-
sider the vast superficial extent occupied by calcareous deposits,
and the enormous collective thickness of these, the mind cannot
fail to be impressed with the immensity of the period demanded
for the formation of these by the agency of such humble and
often microscopic creatures as Corals, Sea-lilies, Foraminifers,
and Shell-fish.

THE FOSSILIFEROUS ROCKS. 29

Amongst the numerous varieties of limestone, a few are of
such interest as to deserve a brief notice. Magnesia limestone
or dolomite, differs from ordinary limestone in containing a cer-
tain proportion of carbonate of magnesia along with the carbon-
ate of lime. The typical dolomites contain a large proportion of
carbonate of magnesia, and are highly crystalline. The ordi-
nary magnesian limestones (such as those of Durham in the
Permian series, and the Guelph Limestones of North America
in the Silurian series) are generally of a yellowish, buff, or
brown color, with a crystalline or pearly aspect, effervescing
with acid much less freely than ordinary limestone, exhibiting
numerous cavities from which fossils have been dissolved out,
and often assuming the most varied and singular forms in con-
sequence of what is called " concretionary action. " Examination
with the microscope shows that these limestones are composed
of an aggregate of minute but perfectly distinct crystals, but that
minute organisms of different kinds, or fragments of larger
fossils, are often present as well. Other magnesian limestones,
again, exhibit no striking external peculiarities by which the
presence of magnesia would be readily recognized, and though
the base of the rock is crystalline, they are replete with the
remains of organized beings. Thus many of the magnesian
limestones of the Carboniferous series of the North of Eng-
land are very like ordinary limestone to look at, through
effervescing less freely with acids, and the microscope proves
them to be charged with remains of Foraminifera and other
minute organisms,

Marbles are of various kinds, all limestones which are suffi-
ciently hard and compact to take a high polish going by this
name. Statuary marble, and most of the celebrated foreign
marbles, are " metamorphic " rocks, of a highly crystalline
nature, and having all traces of their primitive organic struc-
ture obliterated. Many other marbles, however, differ from
ordinary limestone simply in the matter of density. Thus,
many marbles (such as Derbyshire marble) are simply " cri-
noidal limestones " (fig. 9) ; whilst various other British
marbles exhibit innumerable organic remains under the mi-
croscope. Black marbles owe their color to the presence of
very minute particles of carbonaceous matter, in some cases
at any rate ; and they may either be metamorphic, or they may
be charged with minute fossils such as Foraminifera (e.g., the
black limestones of Ireland, and the black marble of Dent, in
Yorkshire).

PRINCIPLES OF PALEONTOLOGY.

" Oolitic " limestones, or " oolites, " as they are often called,
are of interest both to the palaeontologist and geologist. The
peculiar structure to which they owe their name is that the rock
is more or less entirely composed of spheroidal or oval grains,
which vary in size from the head of a small pin or less up to the
size of a pea, and which may be in almost immediate contact with
one another, or may be cemented together by a more or less
abundant calcareous matrix. When the grains are pretty nearly
spherical and are in tolerably close contact, the rock looks very
like the roe of a fish, and the name of " oolite " or ' egg-stone "
is in allusion to this. When the grains are of the size of peas or
upwards, the rock is often called a "pisolite" (Lat. pisum, a
pea). Limestones having this peculiar structure are especially
abundant in the Jurassic formation, which is often called the
" Oolitic series " for this reason ; but essentially similar lime-
stones occur not uncommonly in the Silurian, Devonian, and
Carboniferous formations, and, indeed, in almost all rock groups
in which limestones are largely developed. Whatever may be
the age of the formation in which they occur, and whatever
may be the size of their component " eggs, " the structure of
oolitic limestones is fundamentally the same. All the ordinary
oolitic limestones, namely, consist of little spherical or ovoid
" concretions, " as they are termed, cemented together by a larger
or smaller amount of crystalline carbonate of lime, together, in
many instances, with numerous organic remains of different
kinds (fig. 13). When examined in polished slabs, or in thin sec-
tions prepared for the micro-
scope, each of these little con-
cretions is seen to consist of
numerous concentric coats of
carbonate of lime, which some-
times simply surround an imag-
inary center, but which, more
commonly, have been suc-
cessively deposited round
some foreign body, such as a
little crystal of quartz, a clus-
ter of sand-grains, or a minute
shell. In other cases, as in
some of the beds of the Car-
boniferous limestone in the
North of England, where the
limestone is highly " arenaceous, " there is a modification of the

mg i3.-siice of oolitic limestone
°'

THE FOSSILIFEROUS ROCKS.

oolitic structure. Microscopic sections of these sandy lime-
stones (fig. 14) show numerous generally angular or oval grains
of silica or flint, each of which is commonly surrounded by a
thin coating of carbonate of lime, or sometimes by several such
coats, the whole being cemented together along with the shells
of Foraminifera and other minute fossils by a matrix of crystal-
line calcite. As compared with typical oolites, the concretions
in these limestones are usually much more irregular in shape,
often lengthened out and almost cylindrical, at other times
angular, the central nucleus being of large size, and the sur-
rounding envelope of lime be-
ing very thin, and often exhib-
iting no concentric structure.
In both these and the ordinary
oolites, the structure is funda-
mentally the same. Both have
been formed in a sea, probably
of no great depth, the waters
of which were charged with
carbonate of lime in solution,
whilst the bottom was formed
of sand intermixed with min-
ute shells and fragments of
the skeletons of larger marine
animals. The excess of lime in
the sea-water was precipitated
round the sand-grains, or round
the smaller shells, as so many

nuclei, and this precipitation must often have taken place time
after time, so as to give rise to the concentric structure so char-
acteristic of oolitic concretions. Finally, the oolitic grains thus
produced were cemented together by a further precipitation of
crystalline carbonate of lime from the waters of the ocean.

Phosphate of Lime is another lime-salt, which is of interest
to the palaeontologist. It does not occur largely in the strati-
fied series, but it is found in considerable beds * in the
Laurentian formation, and less abundantly in some later rock-

* Apart from the occurrence of phosphate of lime in actual beds in the
stratified rocks, as in the Laurentian and Silurian series, this salt may
also occur disseminated through the rock, when it can only be detected by
chemical analysis. It is interesting to note that Dr. Hicks has recently
proved the occurrence of phosphate of lime in this disseminated form in
rocks as old as the Cambrian, and that in quantity quite equal to what
is generally found to be present in the later fossiliferous rocks. This
affords a chemical proof that animal life flourished abundantly in the
Cambrian seas.

Fig. 14. — Slice of arenaceous and
oolitic limestone from the Carbonifer-
ous series of Shap, Westmoreland; mag-
nified. The section also exhibits Fora-
minifera and other minute fossils. (Orig-
inal.)

32 PRINCIPLES OF PALEONTOLOGY.

groups, whilst it occurs abundantly in the form of nodules in
parts of the Cretaceous (Upper Greensand) and Tertiary deposits.
Phosphate of lime forms the larger proportion of the earthy
matters of the bones of Vertebrate animals, and also occurs in
less amount in the skeletons of certain of the Invertebrates (e.g.,
Crustacce}. It is, indeed, perhaps more distinctively than
carbonate of lime, an organic compound ; and though the for-
.mation of many known deposits of phosphate of lime cannot be
positively shown to be connected with the previous operation of
living beings, there is room for doubt whether this salt is not
in reality always primarily a product of vital action. The phos-
phatic nodules of the Upper Greensand are erroneously called
" coprolites, " from the belief originally entertained that they
were the droppings or fossilized excrements of extinct animals;
and though this is not the case, there can be little doubt but
that the phosphate of lime which they contain is in this instance
of organic origin. * It appears, in fact, that decaying animal
matter has a singular power of determining the precipitation
around it of mineral salts dissolved in water. Thus, when any
animal bodies are undergoing decay at the bottom of the sea,
they have a tendency to cause the precipitation from the sur-
rounding wa-ter of any mineral matter which may be dissolved in
it ; and the organic body thus becomes a center round which the
mineral matters in question are deposited in the form of a
"concretion" or "nodule.." The phosphatic nodules in question
were formed in a sea in which phosphate of lime, derived from
the destruction of animal skeletons, was held largely in solution ;
and a precipitation of it took place round any body, such as a
decaying animal substance, which happened to be lying on the
sea-bottom, and which offered itself as a favorable nucleus. In
the same way we may explain the formation of the calcareous
nodules, known as " septaria " or " cement stones, " which occur
so commonly in the London Clay and Kimmeridge Clay, and in
which the principal ingredient is carbonate of lime. A similar
origin is to be ascribed to the nodules of clay iron-stone (im-
pure carbonate of iron) which occur so abundantly in the shales
of the Carboniferous series and in other argillaceous deposits;
and a parallel modern example is to be found in the nodules of

* It has been maintained, indeed, that the phosphatic nodules so
largely worked for agricultural purposes, are in themselves actual organic
bodies or true fossils. In a few cases this admits of demonstration, as it
can be shown that the nodule is simply an organism (such as a sponge)
infiltrated with phosphate of lime (Sollas) ; but there are many other cases
in which no actual structure has yet been shown to exist, and as to the
true origin of which it would be hazardous to offer a positive opinion.

THE FOSSILIFEROUS ROCKS. 33

manganese, which were found by Sir Wyville Thomson, in the
Challenger, to be so numerously scattered over the floor of the
Pacific at great depths. In accordance with this mode of
origin, it is exceedingly common to find in the center of all these
nodules, both old and new, some organic body, such as a bone,
a shell, or a tooth, which acted as the original nucleus of pre-
cipitation, and was thus preserved in a shroud of mineral matter.
Many nodules, it is true, show no such nucleus ; but it has been
affirmed that all of them can be shown, by appropriate micro-
scopical investigation, to have been formed round an original
organic body to begin with (Hawkins Johnson).

The last lime-salt which need be mentioned is gypsum, or
sulphate of lime. This substance, apart from the other modes
of occurrence, is not uncommonly found interstratified with the
ordinary sedimentary rocks, in the form of more or less irregu-
lar beds ; and in these cases it has a palaeontological importance,
as occasionally yielding well-preserved fossils. Whilst its exact
mode of origin is uncertain, it cannot be regarded as in itself an
organic rock, though clearly the product of chemical action. To
look at, it is usually a whitish or yellowish-white rock, as coarsely
crystalline as loaf-sugar, or more so; and the microscope shows
it to be composed entirely of crystals of sulphate of lime.

We have seen that the calcareous or lime-containing rocks
are the most important of the group of organic deposits ; whilst
the siliceous or flint-containing rocks may be regarded as the
most important, most typical and most generally distributed of
the mechanically-formed rocks. We have, however, now briefly
to consider certain deposits which are more or less completely
formed of flint ; which, nevertheless, are essentially organic in
their origin.

Flint or silex, hard and intractable as it is, is nevertheless
capable of solution in water to a certain extent, and even of
assuming, under certain circumstances, a gelatinous or viscous
condition. Hence, some hot-springs are impregnated with silica
to a considerable extent ; it is present in small quantity in sea-
water; and there is reason to believe that a minute proportion
must very generally be present in all bodies of fresh water as
well. It is from this silica dissolved in- the water that many
animals and some plants are enabled to construct for themselves
flinty skeletons; and we find that these animals and plants are
and have been sufficiently numerous to give rise to very consider-
able deposits of siliceous matter by the mere accumulation of
their skeletons. Amongst the animals which require special
3

34

PRINCIPLES OF PALEONTOLOGY.

mention in this connection are the microscopic organisms which
are known to the naturalist as Polycystina. These little creatures
are the lowest possible grade of organization, very closely
related to the animals which we have previously spoken of as
Foraminifera, but differing in the fact that they secrete a shell
or skeleton composed of flint instead of lime. The Polycystina
occur abundantly in our present seas ; and their shells are present
in some numbers in the ooze which is found at great depths in
the Atlantic and Pacific oceans, being easily recognized by their
exquisite shape, their glassy transparency, the general presence
of longer or shorter spines, and the sieve-like perforations in
the walls. Both in Barbadoes and in the Nicobar islands occur
geological formations which are composed of the flinty skeletons
of these microscopic animals; the deposit in the former locality
attaining a great thickness, and having been long known to
workers with the microscope under the name of " Barbadoes
earth" (fig. 15).

Fig. 15. — Shells of Polycyatina from
•'•Barbadoes earth ;" greatly magnified.
(Original.)

Fig. 16.— Cases of Diatoms in the Rich-
mond "Infusorial earth ;" highly magni-
fied. (Original.)

In addition to flint-producing animals, we have also the great
group of fresh-water and marine microscopic plants known as
Diatoms, which likewise secrete a siliceous skeleton, often of
great beauty. The skeletons of Diatoms are found abundantly
at the present day in lake-deposits, guano, the silt of estuaries,
and in mud which covers many parts of the sea-bottom; they
have been detected in strata of great age; and in spite of their
microscopic dimensions, they have not uncommonly accumulated
to form deposits of great thickness, and of considerable super-
ficial extent. Thus the celebrated deposit of " tripoli " (" Polir-

THE FOSSILIFEROUS ROCKS. 35

schiefer") of Bohemia, largely worked as polishing-powder, is
composed wholly, or almost wholly, of the flinty cases of Diatoms,
of which it is calculated that no less than forty-one thousand
millions go to make up a single cubic inch of the stone. Another
celebrated deposit is the so-called " Infusorial earth " of Rich-
mond in Virginia, where there is a stratum in places thirty feet
thick, composed almost entirely of the microscopic shells of
Diatoms.

Nodules or layers of flint, or the impure variety of flint
known as chert, are found in limestones of almost all ages from
the Silurian upwards; but they are especially abundant in the
chalk. When these flints are examined in thin and transparent
slices under the microscope, or in polished sections, they are
found to contain an abundance of minute organic bodies — such
as Foraminifera, sponge-spicules, &c. — embedded in a siliceous
basis. In many instances the flint contains larger organisms —
such as a Sponge or Sea-urchin. As the flint has completely
surrounded and infiltrated the fossils which it contains, it is
obvious that it must have been deposited from sea-water in a
gelatinous condition, and subsequently have hardened. N That
silica is capable of assuming this viscous and soluble condition
is known; and the formation of flint may therefore be regarded
as due to the separation of silica from the sea-water and its
deposition round some organic body in a state of chemical
change or decay, just as nodules of phosphate of lime or carbon-
ate of iron are produced. The existence of numerous organic
bodies in flint has long been known ; but it should be added that
a recent observer (Mr. Hawkins Johnson) asserts that the
existence of an organic structure can be demonstrated by suit-
able methods of treatment, even in the actual matrix or basis of
the flint. *

In addition to the deposits formed of flint itself, there are
other siliceous deposits formed by certain silicates, and also of
organic origin. It has been shown, namely — by observations
carried out in our present seas — that the shells of Foraminifera
are liable to become completely infiltrated by silicates (such as
" glauconite, " or silicate of iron and potash). Should the actual
calcareous shell become dissolved away subsequent to this infil-
tration—as is also liable to occur — then, in place of the shells of

* It has been asserted that the flints of the chalk are merely fossil
sponges. No explanation of the origin of flint, however, can be satisfac-
tory, unless it embraces the origin of chert in almost all great limestones
from the Silurian upwards, as well as the common phenomenon of the
silincation of organic bodies (such as corals and shells) which are known
with certainty to have been originally calcareous.

36 PRINCIPLES OF PALEONTOLOGY.

the Foraminifera, we get a corresponding number of green sandy
grains of glauconite., each grain being the cast of a single shell.
It has thus been shown that the green sand found covering the
sea-bottom in certain localities (as found by the Challenger
expedition along the line of the Agulhas current) is really
organic, and is composed of casts of the shells of Foraminifera.
Long before these observations had been made, it had been shown
by Professor Ehrenberg that the green sands of various geologi-
cal formations are composed mainly of the internal casts of the
shells of Foraminifera; and we have thus another and a very
interesting example how rock-deposits of considerable extent and
of geological importance can be built up by the operation of the
minutest living beings.

As regards argillaceous deposits, containing alumina or clay
as their essential ingredient, it cannot be said that any of these
have been actually shown to be of organic origin. A recent
observation by Sir Wyville Thomson would, however, render it
not improbable that some of the great argillaceous accumulations
of past geological periods may be really organic. This dis-
tinguished observer, during the cruise of the Challenger, showed
that the calcareous ooze which has been already spoken of as
covering large areas of the floor of the Atlantic and Pacific at
great depths, and which consists almost wholly of the shells of
Foraminifera, gave place at still greater depths to a red ooze con-
sisting of impalpable clayey mud, colored by oxide of iron, and
devoid of traces of organic bodies. As the existence of this
widely-diffused red ooze, in mid-ocean, and at such great depths,
cannot be explained on the supposition that it is a sediment
brought down into the sea by rivers, Sir Wyville Thomson came
to the conclusion that it was probably formed by the action of the
sea-water upon the shells of Foraminifera. These shells, though
mainly consisting of lime, also contain a certain proportion of
alumina, the former being soluble in the carbonic acid dissolved
in the sea-water, whilst the latter is insoluble. There would
further appear to be grounds for believing that the solvent power
of the sea-water over lime is considerable increased at great
depths. If, therefore, we suppose the shells of Foraminifera
to be in course of deposition over the floor of the Pacific, at
certain depths they would remain unchanged, and would ac-
cumulate to form a calcareous ooze; but at greater depths they
would be acted upon by the water, their lime would be dis-
solved out, their form would disappear, and we should simply have
left the small amount of alumina which they previously contained.

THE FOSSILIFEROUS ROCKS. 37

In process of time this alumina would accumulate to form a bed
of clay; aad as this clay has been directly derived from the
decomposition of the shells of animals, it would be fairly entitled
to be considered an organic deposit. Though not finally estab-
lished, the hypothesis of Sir Wyville Thomson on this subject is
of the greatest interest to the palaeontologist, as possibly serving
to explain the occurrence, especially in the older formations, of
great deposits of argillaceous matter which are entirely destitute
of traces of life.

It only remains, in this connection, to shortly consider the
rock-deposits in which carbon is found to be present in greater
or less quantity. In the great majority of cases where rocks
are found to contain carbon or carbonaceous matter, it can be
stated with certainty that this substance is of organic origin,
though it is not necessarily derived from vegetables. Carbon
derived from the decomposition of animal bodies is not uncom-
mon ; though it never occurs in such quantity from this source
as it may do when it is derived from plants. Thus, many
limestones are more or less highly bituminous ; the celebrated
siliceous flags or so-called " bituminous schists " of Caithness are
impregnated with oily matter apparently derived from the decom-
position of the numerous fishes embedded in them ; Silurian
shales containing Graptolites, but destitute of plants, are not
uncommonly " anthracitic, " and contain a small percentage of
carbon derived from the decay of these zoophytes; whilst the
petroleum so largely worked in North America has not im-
probably an animal origin. That the fatty compounds present
in animal bodies should more or less extensively impregnate
fossiliferous rock-masses, is only what might be expected; but
the great bulk of the carbon which exists stored up in the
earth's crust is derived from plants; and the form in. which it
principally presents itself is that of coal. We shall have to speak
again, and at greater length, of coal, and it is sufficient to say
here that all the true coals, anthracites, and lignites, are of
organic origin, and consist principally of the remains of plants
in a more or less altered condition. The bituminous shales
which are found so commonly associated with beds of coal also
derive their carbon primarily from plants; and the same is
certainly, or probably, the case with similar shales which are
known to occur in formations younger than the Carboniferous.
Lastly, carbon may occur as a conspicuous constituent of rock-
masses in the form of graphite or black-lead. In this form, it
occurs in the shape of detached scales, of veins or strings, or

38 PRINCIPLES OF PALAEONTOLOGY.

sometimes of regular layers ; * and there can be little doubt that
in many instances it has an organic origin, though this is not
capable of direct proof. When present, at any rate, in quantity,
and in the form of layers associated with stratified rocks, as is
often the case in the Laurentian formation, there can be little
hesitation in regarding it as of vegetable origin, and as an
altered coal.

CHAPTER III.

CHRONOLOGICAL SUCCESSION OF THE
FOSSILIFEROUS ROCKS.

The physical geologist, who deals with rocks simply as rocks,
and who does not necessarily trouble himself about what fossils
they may contain, finds that the stratified deposits which form
so large a portion of the visible part of the earth's crust are
not promiscuously heaped together, but that they have a cer-
tain definite arrangement. In each country that he examines,
he finds that certain groups of strata lie above certain other
groups ; and in comparing different countries with one another,
he finds that, in the main, the same groups of rocks are always
found in the same relative position to each other. It is pos-
sible, therefore, for the physical geologist to arrange the known
stratified rocks into a successive series of groups, or " forma-
tions, " having a certain definite order. The establishment of
this physical order amongst the rocks introduces, however, at
once the element of time, and the physical succession of the
strata can be converted directly into a historical or chronolog-
ical succession. This is obvious, when we reflect that any bed
or set of beds of sedimentary origin is clearly and necessarily

* In the Huronian formation of Steel River, on the north shore of
Lake Superior, there exists a bed of carbonaceous matter which is regu-
larly interstratified with the surrounding rocks, and has a thickness of
from 30 to 40 feet. This bed is shown by chemical analysis to contain
about 50 per cent of carbon, partly in the form of graphite, partly in the
form of anthracite; and there can be little doubt but that it is really a
stratum of " metamorphic " coal.

CHRONOLOGICAL SUCCESSION. 39

younger than all the strata upon which it rests, and older than
all those by which it is surmounted.

It is possible, then, by an appeal to the rocks alone, to de-
termine in each country the general physical succession of the
strata, and this " stratigraphical " arrangement, when once de-
termined, gives us the relative ages of the successive groups.
The task, however, of the physical geologist in this matter is
immensely lightened when he calls in palaeontology to his aid,
and studies the evidence of the fossils embedded 'in the rocks.
Not only is it thus much easier to determine the order of suc-
cession of the strata in any given region, but it becomes now
for the first time possible to compare, with certainty and pre-
cision, the order of succession in one region with that which
exists in other regions far distant. The value of fossils as tests
of the relative ages of the sedimentary rocks depends on the
fact that they are not indefinitely or promiscuously scattered
through the crust of the earth, — as it is conceivable that they
might be. On the contrary, the first and most firmly estab-
lished law of Palaeontology is, that particular kinds of fossils
are confined to particular rocks, and particular groups of fossils
are confined to particular groups of rocks. Fossils, then, are
distinctive of the rocks in which they are found — much more
distinctive, in fact, than the mere mineral character of the rock
can be, for that commonly changes as a formation is traced
from one region to another, whilst the fossils remain unaltered.
It would therefore be quite possible for the palaeontologist,
by an appeal to the fossils alone, to arrange the series of sedi-
mentary deposits into a pile of strata having a certain definite
order. Not only would this be possible, but it would be found
— if sufficient knowledge had been brought to bear on both
sides — that the palaeontological arrangement of the strata would
coincide in its details with the stratigraphical or physical
arrangement.

Happily for science, there is no such division between the
palaeontologist and the physical geologist as here supposed ;
but by the combined researches of the two, it has been found
possible to divide the entire series of stratified deposits into a
number of definite rock-groups or formations, which have a
recognized order of succession, and each of which is charac-
terized by possessing an assemblage of organic remains which
do not occur in association in any other formation. Such an
assemblage of fossils, characteristic of any given formation, rep-
resents the life of the particular period in which the formation

40 PRINCIPLES OF PALEONTOLOGY.

was deposited. In this way the past history of the earth
becomes divided into a series of successive life- periods, each of
which corresponds with the deposition of a particular forma-
tion or group of strata.

Whilst particular assemblages of organic forms characterize
particular groups of rocks, it may be further said that, in a
general way, each subdivision of each formation has its own
peculiar fossils, by which it may be recognized by a skilled
worker in Palaeontology. Whenever, for instance, we meet
with examples of the fossils which are known as Graptolites, we
may be sure that we are dealing with Silurian rocks (leaving
out of sight one or two forms doubtfully referred to this family).
We may, however, go much further than this with perfect
safety. If the Graptolites belong to certain genera, we may
be quite certain that we are dealing with Lower Silurian rocks.
Furthermore, if certain special forms are present, we may be
even able to say to what exact subdivision of the Lower Silurian
series they belong.

As regards particular fossils, however, or even particular
classes of fossils, conclusions of this nature require to be accom-
panied by a tacit but well-understood reservation. So far as
our present observation goes, none of the undoubted Grapto-
lites have ever been discovered in rocks later than those known
upon other grounds to be Silurian ; but it is possible that they
might at any time be detected in younger deposits. Similarly,
the species and genera which we now regard as characteristic
of the Lower Silurian, may at some future time be found to
have survived into the Upper Silurian period. We should not
forget, therefore, in determining the age of strata by palseonto-
logical evidence, that we are always reasoning upon generaliza-
tions which are the result of experience alone, and which are
liable to be vitiated by further and additional discoveries.

When the palaeontological evidence as to the age of any
given set of strata is corroborated by the physical evidence, our
conclusions may be regarded as almost certain; but there are
certain limitations and fallacies in the palseontological method
of inquiry which deserve a passing mention. In the first
place, fossils are not always present in the stratified rocks;
many aqueous rocks are unfossiliferous, through a thickness of
hundreds or even thousands of feet of little-altered sediments;
and even amongst beds which do contain fossils, we often meet
with strata of many feet or yards in thickness which are wholly
destitute of any traces of fossils. There are, therefore, to

CHRONOLOGICAL SUCCESSION. 41

begin with, many cases in which there is no palaeontological
evidence extant or available as to the age of a given group
of strata. In the second place, palaeontological observers in
different parts of the world are liable to give different names
to the same fossils, and in all parts of the world they are occa-
sionally liable to group together different fossils under the
same title. Both these sources of fallacy require to be guarded
against in reasoning as to the age of strata from their fossil
remains. Thirdly, the mere fact of fossils being found in beds
which are known by physical evidence to be of different ages,
has commonly led palaeontologists to describe them as dif»-
ferent species. Thus the same fossil, occurring in successive
groups of strata, and with the merely trivial and varietal differ-
ences due to the gradual change in its environment, has been
repeatedly described as a distinct species, with a distinct name,
in every bed in which it was found. We know, however, that
many fossils range vertically through many groups of strata, and
there are some which even pass through several formations.
The mere fact of a difference of physical position ought never
to be taken into account at all in considering and determining
the true affinities of a fossil. Fourthly, the results of experience,
instead of being an assistance, are sometimes liable to operate
as a source of error. When once, namely, a generalization has
been established that certain fossils occur in strata of a certain
age, palaeontologists are apt to infer that all beds containing
similar fossils must be of the same age. There is a presumption,
of course, that this inference would be correct; but it is not a
conclusion resting upon absolute necessity, and there might be
physical evidence to disprove it. Fifthly, the physical geologist
may lead the palaeontologist astray by asserting that the physical
evidence as to the age and position of a given group of beds is
clear and unequivocal, when such evidence may be, in reality,
very slight and doubtful. In this way, the observer may be
readily led into wrong conclusions as to the nature of the organic
remains — often obscure and fragmentary — which it is his business
to examine, or he may be led erroneously to think that previous
generalizations as to the age of certain kinds of fossils are
premature and incorrect. Lastly, there are cases in which, owing
to the limited exposure of the beds, to their being merely of
local development, or to other causes, the physical evidence as
to the age of a given group of strata may be entirely uncertain
and unreliable, and in which, therefore, the observer has to rely
wholly upon the fossils which he may meet with.

42 PRINCIPLES OF PALAEONTOLOGY.

In spite of the above limitations and fallacies, there can be
no doubt as to the enormous value of palaeontology in enab-
ling us to work out the historical succession of the sedimentary
rocks. It may even be said that in any case where there
should appear to be a clear and decisive discordance between
the physical and the palseontological evidence as to the age
of a given series of beds, it is the former that is to be distrusted
rather than the latter. The records of geological science con-
tain not a few cases in which apparently clear physical evidence
of superposition has been demonstrated to have been wrongly
interpreted; but the evidence of palseontology, when in any way
sufficient, has rarely been upset by subsequent investigations.
Should we find strata containing plants of the Coal-measures
apparently resting upon other strata with Ammonites and Belem-
nites, we may be sure that the physical evidence is delusive ; and
though the above is an extreme case, the presumption in all
such instances is rather that the physical succession has been
misunderstood or misconstrued, than that there has been a sub-
version of the recognized succession of life-forms.

We have seen, then, that as the collective result of observa-
tions made upon the superposition of rocks in different localities,
from their mineral characters, and from their included fossils,
geologists have been able to divide the entire stratified series
into a number of different divisions or formations, each charac-
terized by a general uniformity of mineral composition, and by
a special and peculiar assemblage of organic forms. Each of
these primary groups is in turn divided into a series of smaller
divisions, characterized and distinguished in the same way. It is
not pretended for a moment that all these primary rock-groups
can anywhere be seen surmounting one another regularly. *
There is no region upon the earth where all the stratified forma-
tions can be seen together ; and, even when most of them occur
in the same country, they can nowhere be seen all succeeding
each other in their regular and uninterrupted succession. The
reason of this is obvious. There are many places — to take a

* As we have every reason to believe that dry land and sea have ex-
isted, at any rate from the commencement of the Laurentian period to
the present day, it is quite obvious that no one of the great formations
can ever, under any circumstances, have extended over the entire globe.
In other words, no one of the formations can ever have had a greater
geographical extent than that of the seas of the period in which the for-
mation was deposited. Nor is there any reason for thinking that the pro-
portion of dry land to ocean has ever been materially different to what it
is at present, however greatly the areas of sea and land may have changed
as regards their place. It follows from the above, that there is no suf-
ficient basis for the view that the crust of the earth is composed of a
succession of concentric layers, like the coats of an onion, each layer
representing one formation.

CHRONOLOGICAL SUCCESSION. 43

single example — where one may see the Silurian rocks, the
Devonian, and the Carboniferous rocks succeeding one another
regularly, and in their proper order. This is because the
particular region where this occurs was always submerged be-
neath the sea while these formations were being deposited.
There are, however, many more localities in which one would
find the Carboniferous rocks resting unconformably upon the
Silurians without the intervention of any strata which could be
referred to the Devonian period. This might arise from one of
two causes : i. The Silurians might have been elevated above the
sea immediately after their deposition, so as to form dry land
during the whole of the Devonian period, in which case, of
course, no strata of the later age could possibly be deposited in
that area. 2. The Devonian might have been deposited upon the
Silurian, and then the whole might have been elevated above the
sea, and subjected to an amount of denudation sufficient to
remove the Devonian strata entirely. In this case, when the
land was again submerged, the Carboniferous rocks, or any
younger formation, might be deposited directly upon Silurian
strata. From one or other of these causes, then, or from subse-
quent disturbances and denudations, it happens that we can
rarely find many of the primary formations following one
another consecutively and in their regular order.

In no case, however, do we ever find the Devonian resting
upon the Carboniferous, or the Silurian rocks reposing on the
Devonian. We have therefore, by a comparison of many
different areas, an established order of succession of the strati-
fied formations, as shown in the subjoined ideal section of the
crust of the earth (fig. 17).

The main subdivisions of the stratified rocks are known by
the following names : —

1. Laurentian.

2. Cambrian (with Huronian?).

3. Silurian.

4. Devonian or Old Red Sandstone.

5. Carboniferous.

6. Permian

7. Triassic

8. Jurassic or Oolitic.

9. Cretaceous.

10. Eocene.

11. Miocene.

12. Pliocene.

13. Post-tertiary.

> New Red San-dstone.

44

PRINCIPLES OF PALEONTOLOGY.

IDEAL SECTION OF THE CRUST OF THE EARTH.
Fig. 17.

l» Post-tertiary and Recent.
f> Pliocene.

^.V^^^^o^Fvjr^^yH r Miocene.

Eocene.
Cretaceous.

Oolitic or Jurassic.

Triassic.
Permian.

Carboniferous.

Devonian or Old Red Sand-
stone.

Silurian.

Cambrian.
Huronian.

Laurentian.

CHRONOLOGICAL SUCCESSION. 45

Of these primary rock divisions, the Laurentian, Cambrian,
Silurian, Devonian, Carboniferous, and Permian are collectively
grouped together under the name of the Primary or Pal&ozoic
rocks (G. palaios, ancient; zoe, life). Not only do they constitute
the oldest stratified accumulations, but from the extreme diver-
gence between their animals and plants and those now in exist-
ence, they may appropriately be considered as belonging to an
" Old-Life " period of the world's history. The Triassic,
Jurassic, and Cretaceous systems are grouped together as the
Secondary or Mesozoic formations (Gr. mesos, intermediate;
zoe, life); the organic remains of this " Middle- Life " period
being, on the whole, intermediate in their characters between
those of the palaeozoic epoch and those of more modern strata.
Lastly, the Eocene, Miocene, and Pliocene formations are
grouped together as the Tertiary or Kainozoic rocks (Gr. kainos,
new; zoe, life) ; because they constitute a "New-Life" period, in
which the organic remains approximate in character to those now
existing upon the globe. The so-called Post-Tertiary deposits are
placed with the Kainozoic, or may be considered as forming a
separate Quaternary system.

CHAPTER IV.

THE BREAKS IN THE GEOLOGICAL AND
PALMONTOLOGICAL RECORD.

The term " contemporaneous " is usually applied by geolo-
gists to groups of strata in different regions which contain the
same fossils, or an assemblage of fossils in which many iden-
tical forms are present. That is to say, beds which contain
identical, or nearly identical, fossils, however widely separated
they may be from one another in point of actual distance, are
ordinarily believed to have been deposited during the same
period of the earth's history. This belief, indeed, constitutes
the keystone of the entire system of determining the age of
strata by their fossil contents; and if we take the word "con-
temporaneous " in a general and strictly geological sense, this
belief can be accepted as proved beyond denial. We must,
however, guard ourselves against too literal an interpretation

46 PRINCIPLES OF PALEONTOLOGY.

of the word " contemporaneous, " and we must bear in mind
the enormously-prolonged periods of time with which the
geologist has to deal. When we say that two groups of strata
in different regions are " contemporaneous, " we simply mean
that they were formed during the same geological period, and
perhaps at different stages of that period, and we do not mean to
imply that they were formed at precisely the same instant of time.
A moment's consideration will show us that it is only in the
former sense that we can properly speak of strata being " con-
temporaneous ; " and that, in points of fact, beds containing
the same fossils, if occurring in widely distant areas, can hardly
be " contemporaneous " in any literal sense ; but that the very
identity of their fossils is proof that they were deposited one
after the other. If we find strata containing identical fossils
within the limits of a single geographical region — say in Europe
— then there is a reasonable probability that these beds are
strictly contemporaneous, in the sense that they were deposited
at the same time. There is a reasonable probability of this,
because there is no improbability involved in the idea of an
ocean occupying the whole area of Europe, and peopled
throughout by many of the same species of marine animals. At
the present day, for example, many identical species of animals
are found living on the .western coasts of Britain and the eastern
coasts of North America, and beds now in course of deposition
off the shores of Ireland and the seaboard of the state of
New York would necessarily contain many of the same fossils.
Such beds would be both literally and geologically contempora-
neous ; but the case is different if the distance between the areas
where the strata occur be greatly increased. We find, for ex-
ample, beds containing identical fossils (the Quebec or Skiddaw
beds) in Sweden, in the north of England, in Canada, and in
Australia. Now, if all these beds were contemporaneous, in the
literal sense of the term, we should have to suppose that the
ocean at one time extended uninterruptedly between all these
points, and was peopled throughout the vast area thus indicated
by many of the same animals. Nothing, however, that we see at
the present day would justify us in imagining an ocean of such
enormous extent, and at the same time so uniform in its depth,
temperature, and other conditions of marine life, as to allow
the same animals to flourish in it from end to end ; and the
example chosen is only one of a long and ever-recurring series.
It is therefore much more reasonable to explain this, and all
similar cases, as owing to the migration of the fauna, in whole

BREAKS IN THE GEOLOGICAL RECORD. 47

or in part, from one marine area to another. Thus, we may
suppose an ocean to cover what is now the European area, and
to be peopled by certain species of animals. Beds of sediment —
clay, sands, and limestones — will be deposited over the sea-
bottom, and will entomb the remains of the animals as fossils.
After this has lasted fof a certain length of time, the European
area may undergo elevation, or may become otherwise unsuitable
for the perpetuation of its fauna; the result of which would be
that some or all of the marine animals of the area would migrate
to some more suitable region. Sediments would then, be accumu-
lated in the new area to which they had betaken themselves,
and they would then appear, for the second time, as fossils in
a set of beds widely separated from Europe. The second set
of beds would, however, obviously not be strictly or literally
contemporaneous with the first, but would be separated from
them by the period of time required for the migration of the
animals from the one area into the other. It is only in a wide
and comprehensive sense that such strata can be said to be con-
temporaneous.

It is impossible to enter further into this subject here; but it
may be taken as certain that beds in widely remote geographical
areas can only come to contain the same fossils by reason of a
migration having taken place of the animals of the one area to
the other. That such migrations can and do take place is quite
certain, and this is a much more reasonable explanation of the
observed facts than the hypothesis that in former periods the
conditions of life were much more uniform than they are at
present, and that, consequently, the same organisms were able
to range over the entire globe at the same time. It need only be
added, that taking the evidence of the present as explaining the
phenomena of the past — the only safe method of reasoning in
geological matters — we have abundant proof that deposits which
are actually contemporaneous, in the strict sense of the term,
do not contain the same fossils, if far removed from one another
in point of distance. Thus, deposits of various kinds are now
in process of formation in our existing seas, as for example, in.
the Arctic Ocean, the Atlantic, and the Pacific, and marfy of
these deposits are known to us by actual examination and obser-
vation with the sounding-lead and dredge. But it is hardly neces-
sary to add that the animal remains contained in these deposits —
the fossils of some future period — instead of being identical, are
widely different from one another in their characters.

We have seen, then, that the entire stratified series is

48 PRINCIPLES OF PALAEONTOLOGY.

capable of subdivision into a number of definite rock-groups or
" formations, " each possessing a peculiar and characteristic
assemblage of fossils, representing the " life " of the " period " in
which the formation was deposited. We have still to inquire
shortly how it came to pass that two successive formations
should thus be broadly distinguished by their life-forms, and
why they should not rather possess at any rate a majority of
identical fossils. It was originally supposed that this could be
explained by the hypothesis that the close of each formation
was accompanied by a general destruction of all the living
beings of the -period, and that the commencement of each new
formation was signalized by the creation of a number of brand-
new organisms, destined to figure as the characteristic fossils of
the same. This theory, however, ignores the fact that
each formation — as to which we have any sufficient evidence —
contains a few, at least, of the life-forms which existed in the
preceding period; and it invokes forces and processes of which
we know nothing, and for the supposed action of which we can-
not account. The problem is an undeniably difficult one, and it
will not be possible here to give more than a mere outline of
the modern views upon the subject. Without entering into the at
present inscrutable question as to the manner in which new life-
forms are introduced upon the earth, it may be stated that almost
all modern geologists hold that the living beings of any given
formation are in the main modified forms of others which have
preceded them. It is not believed that any general or universal
destruction of life took place at the termination of each geolog-
ical period, or that a general introduction of new forms took
place at the commencement of a new period. It is, on the con-
trary, believed that the animals and plants of any given period
are for the most part (or exclusively) the lineal but modified
descendants of the animals and plants of the immediately pre-
ceding period, and that some of them, at any rate, are continued
into the next succeeding period, either unchanged, or so far
altered as to appear as new species. To discuss these views in
detail would lead us altogether too far, but there is one very
obvious consideration which may advantageously receive some
attention. It is obvious, namely, that the great discordance which
is found to subsist between the animal life of any given forma-
tion and that of the next succeeding formation, and which no
one denies, would be a fatal blow to the views just alluded to,
unless admitting of some satisfactory explanation. Nor is this
discordance one purely of life-forms, for there is often a physical

BREAKS IN THE GEOLOGICAL RECORD. 49

break in the successions of strata as well. Let us therefore
briefly consider how far these interruptions and breaks in the
geological and palaeontological record can be accounted for, and
still allow us to believe in some theory of continuity as opposed
to the doctrine of intermittent and occasional action.

In the first place, it is perfectly clear that if we admit the
conception above mentioned of a continuity of life from the
Laurentian period to the present day, we could never prove
our view to be correct, unless we could produce in evidence
fossil examples of all the kinds of animals and plants that
have lived and died during that period. In order to do this,
we should require, to begin with, to have access to an abso-
lutely unbroken and perfect succession of all the deposits which
have ever been laid down since the beginning. If, however, we
ask the physical geologist if he is in possession of any such
uninterrupted series, he will at once answer in the negative. So
far from the geological series being a perfect one, it is inter-
rupted by numerous gaps of unknown length, many of which we
can never expect to fill up. Nor are the proofs of this far to seek.
Apart from the facts that we have hitherto examined only a
limited portion of the dry land, that nearly two-thirds of the
entire area of the globe is inaccessible to geological investigation
in consequence of its being covered by the sea, that many deposits
can be shown to have been more or less completely destroyed
subsequent to their deposition, and that there may be many
areas in which living beings exist where no rock is in process of
formation, we have the broad fact that rock-deposition only goes
on to any extent in water, and that the earth must have always
consisted partly of dry land and partly of water — at any rate, so
far as any period of which we have geological knowledge is
concerned. There must, therefore, always have existed, at some
part or another of the earth's surface, areas where no deposition
of rock was going on, and the proof of this is to be found in
the well-known phenomenon of " unconformability. " When-
ever, namely, deposition of sediment is continuously going on
within the limits of a single ocean, the beds which are laid down
succeed one another in uninterrupted and regular sequence. Such
beds are said to be " conformable, " and there are many rock-
groups known where one may pass through fifteen or twenty
thousand feet of strata without a break — indicating that the
beds had been deposited in an area which remained continu-
ously covered by the sea. On the other hand, we commonly
find that there is no such regular succession when we pass
4

50 PRINCIPLES OF PALAEONTOLOGY.

from one great formation to another, but that, on the contrary,
the younger formation rests " unconformably, " as it is called,
either upon the formation immediately preceding it in point of
time, or upon some still older one. The essential physical
feature of this unconformability is that the beds of the younger
formation rest upon a worn and eroded surface formed by the
beds of the older series (fig. 18) ; and a moment's considera-
tion will show us what this indicates. It indicates, beyond the

Fig. 18. — Section showing strata of Tertiary age (a) resting upon a worn and eroded
surface of White Chalk (b), the stratification of which is marked by lines of flint.

possibility of misconception, that there was an interval between
the deposition of the older series and that of the newer series of
strata; and that during this interval the older beds were raised
above the sea-level, so as to form dry land, and were subsequently
depressed again beneath the waters, to receive upon their worn
and wasted upper surface the sediments of the later group.
During the interval thus indicated, the deposition of rock must
of necessity have been proceeding more or less actively in other
areas. Every unconformity, therefore, indicates that at the
spot where it occurs, a more or less extensive series of beds must
be actually missing; and though we may sometimes be able to
point to these missing strata in other areas, there yet remains a
number of unconformities for which we cannot at present supply
the deficiency even in a partial manner.

It follows from the above that the series of stratified deposits
is to a greater or less extent irremediably imperfect; and in
this imperfection we have one great cause why we can never
obtain a perfect series of all the animals and plants that have
lived upon the globe. Wherever one of these great physical
gaps occurs, we find, as we might expect, a corresponding break
in the series of life-forms. In other words, whenever we

BREAKS IN THE GEOLOGICAL RECORD. 51

find two formations to be unconformable, we shall always find
at the same time that -there is a great difference in their fossils,
and that many of the fossils of the older formation do not sur-
vive into the newer, whilst many of those in the newer are not
known to occur in the older. The cause of this is, obviously,
that the lapse of time, indicated by the unconformability, has
been sufficiently great to allow of the dying out or modification
of many of the older forms of life, and the introduction of
new ones by immigration.

Apart, however, altogether, from these great physical breaks
and their corresponding breaks in life, there are other reasons
why we can never become more than partially acquainted with
the former denizens of the globe. Foremost amongst these is
the fact that an enormous number of animals possess no hard
parts of the nature of a skeleton, and are therefore incapable,
under any ordinary circumstances, of leaving behind them any
traces of their existence. It is true that there are cases in
which animals in themselves completely soft-bodied are never-
theless able to leave marks by which their former presence can
be detected. Thus every geologist is familiar with the wind-
ing and twisting " trails " formed on the surface of the strata
by sea-worms ; and the impressions left by the stranded
carcases of Jelly-fishes on the fine-grained lithographic slates
of Solenhofen supply us with an example of how a creature
which is little more than " organized sea-water " may still make
an abiding mark upon the sands of time. As a general rule,
however, animals which have no skeletons are incapable of
being preserved as fossils, and hence there must always have
been a vast number of different kinds of marine animals of
which we have absolutely no record whatever. Again, almost
all the fossiliferous rocks have been laid down in water ; and
it is a necessary result of this that the great majority of fossils
are/ the remains of aquatic animals. The remains of air-
breathing animals, whether of the inhabitants of the land or of
the air itself, are comparatively rare as fossils, and the record of
the past existence of these is much more imperfect than is the
case with animals living in water. Moreover, the fossiliferous
deposits are not only almost exclusively aqueous formations,
but the great majority are marine, and only a comparatively
small number have been formed by lakes and rivers. It follows
from the foregoing that the palaeontological record is fullest and
most complete so far as sea-animals are concerned, though even
here we find enormous gaps, owing to the absence of hard struc-

52 PRINCIPLES OF PALAEONTOLOGY.

tures in many great groups ; of animals inhabiting fresh water
our knowledge is rendered still further incomplete by the small
proportion that fluviatile and lacustrine deposits bear to marine ;
whilst we have only a fragmentary acquaintance with the air-
breathing animals which inhabited the earth during past ages.

Lastly, the imperfection of the palaeontological record, due
to the causes above enumerated, is greatly aggravated, espe-
cially as regards the earlier portion of the earth's history, by the
fact that many rocks which contained fossils when deposited
have since been rendered barren of organic remains. The
principal cause of this common phenomenon is what is known
as " metamorphism " — that is, the subjection of the rock to a
sufficient amount of heat to cause a rearrangement of its par-
ticles. When at all of a pronounced character, the result of
metamorphic action is invariably the obliteration of any fossils
which might have been originally present in the rock. Meta-
morphism may effect rocks of any age, though naturally more
prevalent in the older rocks, and to this cause must be set
down an irreparable loss of much fossil evidence. The most
striking example which is to be found of this is the great Lau-
rentian series, which comprises some 30,000 feet of highly-
metamorphosed sediments, but which, with one not wholly un-
disputed exception, has as yet yielded no remains of living
beings, though there is strong evidence of the former existence
in it of fossils.

Upon the whole, then, we cannot doubt that the earth's
crust, so far as yet deciphered by us, presents us with but a
very imperfect record of the past. Whether the known and
admitted imperfections of the geological and palseontological
records are sufficiently serious to account satisfactorily for the
deficiency of direct evidence recognizable in some modern
hypotheses, may be a matter of individual opinion. There can,
however, be little doubt that they are sufficiently extensive to
throw the balance of evidence decisively in favor of some theory
of continuity, as opposed to any theory of intermittent and
occasional action. The apparent breaks which divide the great
series of the stratified rocks into a number of isolated forma-
tions, are not marks of mighty and general convulsions of
nature, but are simply indications of the imperfection of our
knowledge. Never, in all probability, shall we be able to point
to a complete series of deposits, or a complete succession of
life linking one great geological period to another. Neverthe-
less, we may well feel sure that such deposits and such an

BREAKS IN THE GEOLOGICAL RECORD. 53

unbroken succession must have existed at one time. We are
compelled to believe that nowhere in the long series of the
fossiliferous rocks has there been a total break, but that there
must have been a complete continuity of life, and a more or
less complete continuity of sedimentation, from the Laurentian
period to the present day. One generation hands on the lamp
of life to the next, and each system of rocks is the direct off-
spring of those which preceded it in time. Though there has
not been continuity in any given area, still the geological chain
could never have been snapped at one point, and taken up
again at a totally different one. Thus we arrive at the con-
viction that continuity is the fundamental law of geology, as it
is of the other sciences, and that the lines of demarcation between
the great formations are but gaps in our own knowledge.

CHAPTER V.
CONCLUSIONS TO BE DRAWN FROM FOSSILS.

We have already seen that geologists have been led by the
study of fossils to the all-important generalization that the vast
series of the Fossiliferous or Sedimentary Rocks may be divided
into a number of definite groups or " formations, " each of which
is characterized by its organic remains. It may simply be
repeated here that these formations are not properly and
strictly characterized by the occurrence in them of any one par-
ticular fossil. It may be that a formation contains some
particular fossil or fossils not occurring out of that formation,
and that in this way an observer may identify a given group with
tolerable certainty. It very often happens, indeed, that some
particular stratum, or sub-group of series, contains peculiar
fossils, by which its existence may be determined in various
localities. As before remarked, however, the great formations
are characterized properly by the association of certain fossils,
by the predominance of certain families or orders, or by an
assemblage of fossil remains representing the " life " of the
period in which the formation was deposited.

Fossils, then, enable us to determine the age of the deposits
in which they occur. Fossils further enable us to come to very
important conclusions as to the mode in which the fossiliferous
bed was deposited, and thus as to the condition of the particular
district or region occupied by the fossiliferous bed at the time
of the formation of the latter. If, in the first place, the bed

54 PRINCIPLES OF PALAEONTOLOGY.

contains the remains of animals such as now inhabit rivers, we
know that it is " fluviatile " in its origin, and that it must at
one time have either formed an actual riverbed, or been deposited
by the overflowing of an ancient stream. Secondly, if the bed
contain the remains of shell-fish, minute crustaceans, or fish,
such as now inhabit lakes, we know that it is " lacustrine, " and
was deposited beneath the waters of a former lake. Thirdly, if
the bed contain the remains of animals such as now people the
ocean, we know that it is " marine " in its origin, and that it is
a fragment of an old sea-bottom.

We can, however, often determine the conditions under
which a bed was deposited with greater accuracy than this. If,
for example, the fossils are of kinds resembling the marine
animals now inhabiting shallow waters, if they are accompanied
by the detached relics of terrestrial organisms, or if they are
partially rolled and broken, we may conclude that the fossil-
iferous deposit was laid down in a shallow sea, in the immediate
vicinity of a coast-line, or as an actual shore-deposit. If, again,
the remains are those of animals such as now live in the deeper
parts of the ocean, and there is a very sparing intermixture of
extraneous fossils (such as the bones of birds or quadrupeds,
or the remains of plants), we may presume that the deposit is
one of deep water. In other cases, we may find, scattered
through the rock, and still in their natural position, the valves
of shells such as we know at the present day as living buried
in the sand or mud of the sea-shore or of estuaries. In other
cases, the bed may obviously have been an ancient coral-reef,
or an accumulation of social shells, like Oysters. Lastly, if we
find the deposit to contain the remains of marine shells, but
that these are dwarfed of their fair proportions and distorted
in figure, we may conclude that it was laid down in a brackish
sea, such as the Baltic, in which the proper saltness was want-
ing, owing to its receiving an excessive supply of fresh water.

In the preceding, we have been dealing simply with the
remains of aquatic animals, and we have seen that certain con-
clusions can be accurately reached by an examination of these.
As regards the determination of the conditions of deposition
from the remains of aerial and terrestrial animals, or from
plants, there is not such an absolute certainty. The remains
of land-animals would, of course, occur in " sub-aerial " deposits
— that is, in beds, like blown sand, accumulated upon the land.
Most of the remains of land-animals, however, are found in
deposits which have been laid down in water, and they owe

CONCLUSIONS TO BE DRAWN FROM FOSSILS. 55

their present position to the fact that their former owners were
drowned in rivers or lakes, or carried out to sea by streams.
Birds, Flying Reptiles, and Flying Mammals might also simi-
larly find their way into aqueous deposits ; but it is to be re-
membered that many birds and mammals habitually spend a
great part of their time in the water, and that these might there-
fore be naturally expected to present themselves as fossils in
Sedimentary Rocks. Plants, again, even when undoubtedly
such as must have grown on land, do not prove that the bed
in which they occur was formed on land. Many of the remains
of plants known to us are extraneous to the bed in which they
are now found, having reached their present site by falling into
lakes or rivers, or being carried out to sea by floods or gales of
wind. There are, however, many cases in which plants have
undoubtedly grown on the very spot where we now find them.
Thus it is now generally admitted that the great coal-fields
of the Carboniferous age are the result of the growth in situ
of the plants which compose coal, and that these grew on vast
marshy or partially submerged
tracts of level alluvial land.,
We have, however, distinct
evidence of old land-surfaces,
both in the Coal-measures and
in other cases (as, for in-
stance, in the well-known
"dirt-bed" of the Purbeck
seri'es). When, for example,
we find the erect stumps of
trees standing at right angles
to the surrounding strata, we
know that the surface through
which these send their roots
was at one time the surface of
the dry land, or in other
words, was an ancient soil
(fig. 19).

In many cases fossils en-
able us to come to important
conclusions as to the climate
of the period in which they

lived, but only a few in- FIR. 19,-ErectTree containing Reptilian
stances of this can be here remains. Coal-measures, Nova Scotia,
adduced. As fossils in the

56 PRINCIPLES OF PALAEONTOLOGY.

majority of instances are the remains of marine animals, it is
mostly the temperature of the sea which can alone be determined
in this way; and it is important to remember that, owing to the
existence of heated currents, the marine climate of a given area
does not necessarily imply a correspondingly warm climate in
the neighboring land. Land-climates can only be determined by
the remains of land-animals or land-plants, and these are com-
paratively rare as fossils. It is also important to remember that all
conclusions on this head are really based upon the present dis-
tribution of animal and vegetable life on the globe, and are
therefore liable to be vitiated by the following considerations : —

a. Most fossils are extinct, and it is not certain that the
habits and requirements of any extinct animal were exactly
similar to those of its nearest living relative.

b. When we get very far back in time, we meet with groups
of organisms so unlike anything we know at the present day as
to render all conjectures as to climate found upon their sup-
posed habits more or less uncertain and unsafe.

c. In the case of marine animals, we are as yet very far
from knowing the exact limits of distribution of many species
within our present seas ; so that conclusions drawn from living
forms as to extinct species are apt to prove incorrect. For
instance, it has recently been shown that many shells formerly
believed to be confined to the Arctic Seas have, by reason of the
extension of Polar currents, a wide range to the south ; and.
this has thrown doubt upon the conclusions drawn from fossil
shells as to the Arctic conditions under which certain beds were
supposed to have been deposited.

d. The distribution of animals at the present day is certainly
dependent upon other conditions beside climate alone ; and
the causes which now limit the range of given animals are
certainly such as belong to the existing order of things. But
the establishment of the present order of things does not date
back in many cases to the introduction of the present species of
animals. Even in the case therefore, of existing species of
animals, it can often be shown that the past distribution of the
species was different formerly to what it is now, not necessarily
because the climate has changed, but because of the alteration
of other conditions essential to the life of the species of con-
ducing to its extension.

Still, we are in many cases able to draw completely reliable
conclusions as to the climate of a given geological period, by
an examination of the fossils belonging to that period. Among

CONCLUSIONS TO BE DRAWN FROM FOSSILS. 57

the more striking examples of how the past climate of a region
may be deduced from the study of the organic remains con-
tained in its rocks, the following may be mentioned: It has
been shown that in Eocene times, or at the commencement
of the Tertiary period, the climate of what is now Western
Europe was of a tropical or sub-tropical character. Thus the
Eocene beds are found to contain the remains of shells such
as now inhabit tropical seas, as, for example, Cowries and
Volutes; and with these are the fruits of palms, and the
remains of other tropical plants. It has been shown, again,
that in Miocene times, or about the middle of the Tertiary
period, Central Europe was peopled with a* luxuriant flora
resembling that of the warmer parts of the United States, and
leading to the conclusion that the mean annual temperature
must have been at least 30° hotter than it is at present. It
has been shown that, at the same time, Greenland, now buried
beneath a vast ice-shroud, was warm enough to support a large
number of trees, shrubs, and other plants, such as inhabit the
temperate regions of the globe. Lastly, it has been shown,
upon physical as well as palaeontological evidence, that the
greater part of the North Temperate Zone, at a comparatively
recent geological period, has been visited with all the rigors
of an Arctic climate, resembling that of Greenland at the pres-
ent day. This is indicated by the occurrence of Arctic shells
in the superficial deposits of this period, whilst the Musk-ox
and the Reindeer roamed far south of their present limits.

Lastly, it was from the study of fossils that geologists learnt
originally to comprehend a fact which may be regarded as of
cardinal importance in all modern geological theories and
speculations — namely, that the crust of earth is liable to
local elevations and subsidences. For long after the remains
of shells and other marine animals were for the first time ob-
served in the solid rocks forming the dry land, and at great
heights above the sea-level, attempts were made to explain this
almost unintelligible phenomenon upon the hypothesis that
the fossils in question were not really the objects they repre-
sented, but were in truth mere lusus naturce, due to some
" plastic virtue latent in the earth. " The common-sense of
scientific men, 'however, soon rejected this idea, and it was
agreed by universal consent that these bodies really were the
remains of animals which formerly lived in the sea. When
once this was admitted, the further steps were comparatively
easy, and at the present day no geological doctrine stands on

58 PRINCIPLES OF PALAEONTOLOGY.

a firmer basis than that which teaches us that our present con-
tinents and islands, fixed and immovable as they appear, have
been repeatedly sunk beneath the ocean.

CHAPTER VI
THE BIOLOGICAL RELATIONS OF FOSSILS.

Not only have fossils, as we have seen, a most important
bearing upon the sciences of Geology and Physical Geography,
but they have relations of the most complicated and weighty
character with the numerous problems connected with the
study of living beings, or in other words, with the science of
Biology. To such an extent is this the case, that no adequate
comprehension of Zoology and Botany, in their modern form,
is so much as possible without some acquaintance with the
types of animals and plants which have passed away. There
are also numerous speculative questions in the domain of vital
science, which, if soluble at all, can only hope to find their key
in researches carried out on extinct organisms. To discuss
fully the biological relations of fossils would, therefore, afford
matter for a separate treatise; and all that can be done here "is
to indicate very cursorily the principal points to which the
attention of the palseontological student ought to be directed.

In the first place, the great majority of fossil animals and
plants are " extinct " — that is to say, they belong to species
which are no longer in existence at the present day. So far,
however, from there being any truth in the old view that there
were periodic destructions of all the living beings in existence
upon the earth, followed by a corresponding number of new
creations of animals and plants, the actual facts of the case show
that the extinction of old forms and the introduction of nevr
forms have been processes constantly going on throughout the
whole of geological time. Every species seems to come into
being at a certain definite point of time, and to finally disappear
at another definite point ; though there are few instances
indeed, if there are any, in which our present knowledge would
permit us safely to fix with precision the times of entrance and
exit. There are, moreover, marked differences in the actual
time during which different species remained in existence, and

THE BIOLOGICAL RELATIONS OF FOSSILS, 59

therefore corresponding differences in their "vertical range" or,
in other words, in the actual amount and thickness of strata
through which they present themselves as fossils. Some species
are found to range through two or even three formations, and
a few have an even more extended life. More commonly the
species which begin in the commencement of a great forma-
tion die out at or before its close, whilst those which are
introduced for the first time near the middle or end of the
formation may either become extinct, or may pass on into the
next succeeding formation. As a general rule, it is the animals
which have the lowest and simplest organization that have the
longest range in time, and the additional possession of micro-
scopic or minute dimensions seems also to favor longevity.
Thus some of the Foraminifera appear to have survived, with
little or no perceptible alteration, from the Silurian period to
the present day; whereas large and highly-organized animals,
though long-lived as individuals, rarely seem to live long speci-
fically, and have, therefore, usually a restricted vertical range.
Exceptions to this, however are occasionally to be found in
some " persistent types, " which extend through a succession of
geological periods with very little modification. Thus the ex-
isting Lampshells of the genus Lingula are little changed from
the Lingula which swarmed in the Lower Silurian seas; and
the existing Pearly Nautilus is the last descendant of a clan
nearly as ancient. On the other hand, some forms are singu-
larly restricted in their limits, and seem to have enjoyed a
comparatively brief lease of life. An example of this is to
be found in many of the Ammonites — close allies of the Nau-
tilus— which are often confined strictly to certain zones of strata,
in some cases of very insignificant thickness.

Of the causes of extinction amongst fossil animals and
plants, we know little or nothing. All we can say is, that the
attributes which constitute a species do not seem to be intrin-
sically endowed with permanence, any more than the attributes
which constitute an individual, though the former may endure
whilst many successive generations of the latter have dis-
appeared. Each species appears to have its own life-period,
its commencement, its culmination, and its gradual decay ; and the
life-periods of different species may be of very different
duration.

From what has been said above, it may be gathered that
our existing species of animals and plants are, for the most
part, quite of modern origin, using the term " modern " in its

6o PRINCIPLES OF PALEONTOLOGY.

geological acceptation. Measured by human standards, the
majority of existing animals (which are capable of being
preserved as fossils) are known to have a high antiquity; and
some of them can boast of a pedigree which even the geologist
may regard with respect. Not a few of our shell-fish are known
to have commenced their existence at some point of the
Tertiary period; one Lampshell (Terebratulina caput-serpentis}
is believed to have survived since the Chalk; and some of the
Foraminifera date, at any rate, from the Carboniferous period.
We learn from this the additional fact that our existing animals
and plants do not constitute an assemblage of organic forms
which were introduced into the world collectively and simul-
taneously, but that they commenced their existence at very
different periods, some being extremely old, whilst others may
be regarded as comparatively recent animals. And this intro-
duction of the existing fauna and flora was a slow and gradual
process, as shown admirably by the study of the fossil shells
of the Tertiary period. Thus, in the earlier Tertiary period,
we find about 95 per cent of the known fossil shells to be species
that are no longer in existence, the remaining 5 per cent being
forms which are known to live in our present seas. In the
middle of the Tertiary period we find many more recent and
still existing species of shells, and the extinct types are much
fewer in number ; and this gradual introduction of forms now
living goes on steadily, till, at the close of the Tertiary period,
the proportions with which we started may be reversed, as
many as 90 or 95 per cent of the fossil shells being forms still
alive, while not more than 5 per cent may have disappeared.

All known animals at the present day may be divided into
some five or six primary divisions, which are known technically
as " sub-kingdoms. " Each of these sub-kingdoms * may be
regarded as representing a certain type or plan of structure,
and all the animals comprised in each are merely modified forms
of this common type. Not only are all known living animals
thus reducible to some five or six fundamental plans of struc-
ture, but amongst the vast series of fossil forms no one has
yet been found — however unlike any existing animal — to possess
peculiarities which would entitle it to be placed in a new sub-
kingdom. All fossil animals, therefore, are capable of being
referred to one or other of the primary divisions of the animal
kingdom. Many fossil groups have no closely-related group

* In the Appendix a brief definition is given of the sub-kingdoms, and
the chief divisions of each are enumerated.

THE BIOLOGICAL RELATIONS OF FOSSILS, 61

now in existence ; but in no case do we meet with any grand
structural type which has not survived to the present day.

The old types of life differ in many respects from those now
upon the earth ; and the further back we pass in time, the
more marked does this divergence become. Thus, if we were
to compare the animals which lived in the Silurian seas with
those inhabiting our present oceans, we should in most in-
stances find differences so great as almost to place us in
another world. This divergence is the most marked in the
Palaeozoic forms of life, less so in those of the Mesozoic period,
and less still in the Tertiary period. Each successive formation
has therefore presented us with animals becoming gradually
more and more like those now in existence ; and though there
is an immense and striking difference between the Silurian ani-
mals and those of to-day, this difference is greatly reduced if
we compare the Silurian fauna with the Devonian; that again
with the Carboniferous ; and so on till we reach the present.

It follows from the above that the animals of any given
formation are more like those of the next formation below,
and of the next formation above, than they are to any others;
and this fact of itself is an almost inexplicable one, unless we
believe that the animals of any given formation are, in part at
any rate, the lineal descendants of the animals of the preced-
ing formation, and the progenitors, also in part at least, of the
animals of the succeeding formation. In fact, the palaeon-
tologist is so commonly confronted with the phenomenon of
closely-allied forms of animal life succeeding one another in
point of time, that he is compelled to believe that such forms
have been developed from some common ancestral type by
some process of " evolution. " On the other hand, there are
many phenomena, such as the apparently sudden introduction
of new forms throughout all past time, and the common occur-
rence of wholly isolated types, which cannot be explained in
this way. Whilst it seems certain, therefore, that many of the
phenomena of the succession of animal life in past periods can
only be explained by some law of evolution, it seems at the
same time certain that there has always been some other
deeper and higher law at work, on the nature of which it
would be futile to speculate at present.

Not only do we find that the animals of each successive
formation become gradually more and more like those now
existing upon the globe, as we pass from the older rocks into
the newer, but we also find that there has been a gradual pro-

62 PRINCIPLES OF PALEONTOLOGY.

gression and development in the types of animal life which
characterize the geological ages. If we take the earliest-known
and the oldest examples of any given group of animals, it can
sometimes be shown that these primitive forms, though in
themselves highly organized, possessed certain characters such
as are now only seen in the young of their existing representa-
tives. In technical language, the early forms of life in some
instances possess " embryonic " characters, though this does
not prevent them often attaining a size much more gigantic
than their nearest living relatives. Moreover, the ancient forms
of life are often what is called " comprehensive types " — that
is to say, they possess characters in combination such as we
nowadays only find separately developed in different groups of
animals. Now, this permanent retention of embryonic char-
acters and this " comprehensiveness " of structural type are signs
of what a zoologist considers to be a comparatively low grade of
organization ; and the prevalence of these features in the earlier
forms of animals is a very striking phenomenon, though they
are none the less perfectly organized so far as their own type
is concerned. As we pass upwards in the geological scale, we
find that these features gradually disappear, higher and ever
higher forms are introduced, and " specialization " of type takes
the place of the former comprehensiveness. We shall have
occasion to notice many of the facts on which these views are
based at a later period, and in connection with actual examples.
In the meanwhile, it is sufficient to state, as a widely-accepted
generalization of palaeontology, that there has been in the past
a general progression of organic types, and that the appearance
of the lower forms of life has in the main preceded that of
the higher forms in point of time.

PART II.

HISTORICAL PALEONTOLOGY.

PART II.

CHAPTER VII.
THE LAURENTIAN AND HURON I AN PERIODS.

The Laurentian Rocks constitute the base of the entire strati-
fied series, and are, therefore, the oldest sediments of which
we have as yet any knowledge. They are more largely and
more typically developed in North America, and especially in
Canada, than in any known part of the world, and they derive
their title from the range of hills which the old French geog-
raphers named the " Laurentides. " These hills are com-
posed of Laurentian Rocks, and form the watershed between
the valley of the St Lawrence river on the one hand, and the
great plains which stretch northwards to Hudson Bay on the
other hand. The main area of these ancient deposits forms
a great belt of rugged and undulating country, which extends
from Labrador westwards to Lake Superior, and then bends
northwards towards the Arctic Sea. Throughout this extensive
area the Laurentian Rocks for the most part present themselves
in the form of low, rounded, ice-worn hills, which, if generally
wanting in actual sublimity, have a certain geological grandeur
from the fact that they " have endured the battles and the storms
of time longer than any other mountains" (Dawson). In some
places, however, the Laurentian Rocks produce scenery of the
most magnificent character, as in the great gorge cut through
them by the river Saguenay, where they rise at times into verti-
cal precipices 1500 feet in height. In the famous group of
the Adirondack mountains, also, in the state of New York
they form elevations no less than 6000 feet above the level of
the sea. As a general rule, the character of the Laurentian
region is that of a rugged, rocky, rolling country, often densely
timbered, but rarely well fitted for agriculture, and chiefly
attractive to the hunter and the miner.

As regards its mineral characters, the Laurentian series is

5 65

66 HISTORICAL PALAEONTOLOGY.

composed throughout of metamorphic and highly crystalline
rocks, which are in a high degree crumpled, folded, and faulted.
By the late Sir William Logan the entire series was divided
into two great groups, the Lower Laurentian and the Upper
Laurentian, of which the latter rests unconformably upon the
truncated edges of the former, and is in turn unconformably
overlaid by strata of Huronian and Cambrian age (fig. 20).

The Lozver Laurentian series attains the enormous thickness
of over 20,000 feet, and is composed mainly of great beds of
gneiss, altered sandstones (quartzites), mica-schist, hornblende-
schist, magnetic iron-ore, and haematite, together with masses of
limestone. The limestones are especially interesting, and have an

Fig. 20— Diagrammatic section of the Laurentian Rocks In LowerCanada. a Lower
Laurentian; 6 Upper Laurentian, resting unconformably upon the lower series; cCam-
brian strata (Potsdam Sandstone), resting unconformably on the Upper Laurentian.

extraordinary development — three principal beds being known,
of which one is not less than 1500 feet thick; the collective
thickness of the whole being about 3500 feet.

The Upper Laurentian series, as before said, reposes uncon-
formably upon the Lower Laurentian, and attains a thickness
of at least 10,000 feet. Like the preceding, it is wholly meta-
morphic, and is composed partly of masses of gneiss and quartz-
ite; but it is especially distinguished by the possession of great
beds of felspathic rock, consisting principally of "Labrador
felspar. "

Though typically developed in the great Canadian area
already spoken of, the Laurentian Rocks occur in other localities,
both in America and in the Old World. In Britain, the so-
called " fundamental gneiss " of the Hebrides and of Suther-
landshire is probably of Lower Laurentian age, and the " hy-
persthene rocks " of the Isle of Syke may, with great proba-
bility, be regarded as referable to the Upper Laurentian. In
other localities in Great Britain (as in St. David's, South
Wales; the Malvern Hills; and the North of Ireland) occur
ancient metamorphic deposits which also are probably refer-
able to the Laurentian series. The so-called " primitive gneiss "
of Norway appears to belong to the Laurentian, and the
ancient metamorphic rocks of Bohemia and Bavaria may be
regarded as being approximately of the same age.

By some geological writers the ancient and highly meta-

THE LAURENTIAN AND HURONIAN PERIODS. 67

morphosed sediments of the Laurentian and the succeeding
Huronian series have been spoken of as the " Azoic rocks "
(Gr. a, without; zoe, life) ; but even if we were wholly destitute
of any evidence of life during these periods, this name would be
objectionable upon theoretical grounds. If a general name be
needed, that of " Eozoic " (Gr. eos, dawn; zoe, life), proposed
by Principal Dawson, is the most appropriate. Owing to their
metamorphic condition, geologists long despaired of ever de-
tecting any traces of life in the vast pile of strata which con-
stitute the Laurentian System. Even before any direct traces
were discovered, it was, however, pointed out that there were
good reasons for believing that the Laurentian seas had been
tenanted by an abundance of living beings. These reasons
are briefly as follows: — (i) Firs'tly, the Laurentian series con-
sists, beyond question, of marine sediments which originally
differed in no essential respect from those which were subse-
quently laid down in the Cambrian or Silurian periods. (2)
In all formations later than the Laurentian, any limestones
which are present can be shown, with few exceptions, to be
organic rocks, and to be more or less largely made up of the
comminuted debris of marine or fresh-water animals. The
Laurentian limestones, in consequence of the metamorphism
to which they have been subjected, are so highly crystalline
(fig. 21 ) that the microscope fails to detect any organic struc-
ture in the rock, and no fos-
sils beyond those which will
be spoken of immediately have
as yet been discovered in
them. We know, however, of
numerous cases in which lime-
stones, of later age, and un-
doubtedly organic to begin
with, have been rendered so
intensely crystalline by meta-
morphic action that all traces
of organic structure have been
obliterated. We have there-
fore, by analogy, the strongest „,. 2l.-Sectlon of Lower Laurentian
possible ground for believing Limestone from Hull, Ottawa; enlarged
, , 1 , r T ' five diameters. The rock is very highly

that the vast beds of Lauren- crystalline, and contains mica and other
tion UmAcf^tiA Jiowo Kooti ^t-Irr minerals. The irregular black masses in
tian limestone have been orig- n are graphite. (Original.)

inally organic in their origin,

and primitively composed, in the main, of the calcareous skele-

68 HISTORICAL PALAEONTOLOGY.

tons of marine animals. It would, in fact, be a matter of
great difficulty to account for the formation of these great cal-
careous masses on any other hypothesis. (3) The occurrences of
phosphate of lime in the Laurentian Rocks in great abundance,
and sometimes in the form of irregular beds, may very possibly
be connected with the former existence in the strata of the re-
mains of marine animals of whose skeletons this mineral is a con-
stituent. (4) The Laurentian Rocks contain a vast amount of
carbon in the form of black-lead or graphite. This mineral is
especially abundant in the limestones, occurring in regular beds,
in veins or strings, or disseminated through the body of the lime-
stone in shape of crystals, scales, or irregular masses. The
amount of graphite in some parts of the Lower Laurentian is
so great that it has been calculated as equal to the quantity of
carbon present in an equal thickness of the Coal-measures.
The general source of solid carbon in the crust of the earth
is, however, plant-life; and it seems impossible to account for
the Laurentian graphite, except upon the supposition that it
is metamorphosed vegetable matter. (5) Lastly, the great
beds of iron-ore (peroxide and magnetic oxide) which occur
in the Laurentian series interstratified with the other rocks,
point with great probability to the action of vegetable lif e ;
since similar deposits in later formations can commonly be
shown to have been formed by the deoxidizing power of vege-
table matter in a state of decay.

In the words of Principal Dawson, " any one of these rea-
sons might, in itself, be held insufficient to prove so great and,
at first sight, unlikely a conclusion as that of the existence of
abundant animal and vegetable life in the Laurentian; but the
concurrence of the whole in a series of deposits unquestion-
ably marine, forms a chain of evidence so powerful that it
might command belief even if no fragment of any organic or
living form or structure had ever been recognized in these an-
cient rocks. " Of late years, however, there have been dis-
covered in the Laurentian Rocks certain bodies which are
believed to be truly the remains of animals, and of which by
far the most important is the structure known under the now
celebrated name of Eozo'dn. If truly organic, a very special
and exceptional interest attaches itself toEozoon, as being the
most ancient fossil animal of which we have any knowledge;
but there are some who regard it really a peculiar form of
mineral structure, and a severe, protracted, and still unfinished
controversy has been carried on as to its nature. Into this

THE LAURENTIAN AND HURONIAN PERIODS. 69

controversy it is wholly unnecessary to enter here ; and it will
be sufficient to briefly explain the structure of Eozo'on, as eluci-
dated by the elaborate and masterly investigations of Car-
penter and Dawson, from the standpoint that it is a genuine
organism — the balance of evidence up to this moment inclin-
ing decisively to this view.

The structure known as Eozo'dn is found in various localities
in the Lower Laurentian limestones of Canada, in the form of
isolated masses or spreading layers, which are composed of
thin alternating laminae, arranged more or less concentrically
(fig. 22). The laminae of these masses are usually of different

Fig. 22.— Fragment of Eozoon, of the natural size, showing alternate laminae
of loganlte and dolomite. (After Dawson.)

colors and composition; one series being white, and composed
of carbonate of lime — whilst the laminae of the second series
alternate with the preceding, are green in color, and are found
by chemical analysis to consist of some silicate, generally ser-
pentine or the closely-related " loganite. " In some instances,
however, all the laminae are calcareous, the concentric arrange-
ment still remaining visible in consequence of the fact that
the laminae are composed alternately of lighter and darker
colored limestone.

When first discovered, the masses of Eozo'dn were supposed
to be of a mineral nature; but their striking general resem-
blance to the undoubted fossils which will be subsequently
spoken of under the name of Stromatopora was recognized by
Sir William Logan, and specimens were submitted for minute
examination, first to Principal Dawson, and subsequently to
Dr. W. B. Carpenter. After a careful microscopic examina-
tion, these two distinguished observers came to the conclusion
that Eozoon was truly organic, and in this opinion they were

70

HISTORICAL PALEONTOLOGY.

li^ife1 «•"''• " ."^••5

afterwards corroborated by other high authorities (Mr. W. K.
Parker, Professor Rupert Jones, Mr. H. B. Brady, Professor
Giimbel, &c.) Stated briefly, the structure of Eosoon, as ex-
hibited by the microscope, is as follows: —

The concentrically-laminated mass of Eozo'dn is composed
of numerous calcareous layers, representing the original skele-
ton of the organism (fig. 23, b). These calcareous layers serve
to separate and de-
fine a series of cham-
bers arranged in sue- £>- „. '...,. "•••...•••—•..^^

cessive tiers, one
above the other (fig.
23, A, B , C) ; and
they are perforated
not only by passages
(fig. 23, c), which
serve to place suc-
cessive tiers of cham-
bers in communica-
tion, but also by a
system of delicate

branching canals (fig.

Fig. 23.— Diagram of a portion of Eozoon cut verti-

23, d), Moreover, cally. A, B, C, Three tiers of chambers communicating

tViA ^ntral onrl r\rin with one another by slightly constructed apertures: a a,

~ The true shell-wall, perforated by numerous delicate

cipal portion of each tubes; & 6, The main calcareous skeleton ("intermedi-
ate skeleton"); c, Passage of communication ("stolon-

calcareous layer, With passage") from one tier of chambers to another; d,
.1, '£. A 1 Ramifying tubes in the calcareous skeleton. (After

canal- Carpenter.) .
system just spoken

of, is bound both above and below by a thin lamina which has
a structure of its own, and which may be regarded as the proper
shell-wall (fig. 23, a a}. This proper wall forms the actual lin-
ing of the chambers, as well as the outer surface of the whole
mass; and it is perforated with numerous fine vertical tubes
(fig. 24, a a), opening into the chambers and on to the sur-
face by corresponding fine pores. From the resemblance of
this tubulated layer to similar structures in the shell of the
Nummulite, it is often spoken of as the " Nummuline layer. "
The chambers are sometimes piled up one above the other in
an irregular manner ; but they are more commonly arranged
in regular tiers, the separate chambers being marked off from
one another by projections of the wall in the form of parti-
tions, which are so far imperfect as to allow of a free communi-
cation between contiguous chambers. In the original condition

THE LAURENTIAN AND HURONIAN PERIODS. 71

of the organism, all these chambers, of course, must have
been filled with living matter ; but they are found in the present
state of the fossil to be generally filled with some silicate, such
as serpentine, which not only fills the actual chambers, but has

Fig, 24.— Portion of one of the calcareous layers of Eozoon, magnified 100 diameters,
a a, The proper wall ("Nummuline layer") of one of the chambers, showing the fine
vertical tubuli with which it is penetrated, and which are slightly bent along the line
a' «', c c. The intermediate skeleton, with numerous branched canals. The oblique
lines are the cleavage planes of the carbonate of lime, extending across both the in-
termediate skeleton and the proper wall. (After Carpenter.)

also penetrated the minute tubes of the proper wall and the
branching canals of the intermediate skeleton. In some cases
the chambers are simply filled with crystalline carbonate of
lime. When the originally porous fossil has been permeated
by a silicate, it is possible to dissolve away the whole of the
calcareous skeleton by means of acids, leaving an accurate and
beautiful cast of the chambers and the tubes connected with
them in the insoluble silicate.

The above are the actual appearances presented by Eozoon
when examined microscopically, and it remains to see how
far they enable us to decide upon its true position in the
animal kingdom. Those who wish to study this interesting
subject in detail must consult the admirable memoirs by Dr.
W. B. Carpenter and Principal Dawson : it will be enough
here to indicate the results which have been arrived at. The
only animals at the present day which possess a continuous
calcareous skeleton, perforated by pores and penetrated by
canals, are certain organisms belonging to the group of the

72 HISTORICAL PALEONTOLOGY.

Foraminifera. We have had occasion before to speak of these
animals, and as they are not conspicuous or commonly-known
forms of life, it may be well to say a few words as to the
structure of the living representatives of the group. The
Foraminifera are all inhabitants of the sea, and are mostly of
small or even microscopic dimensions. Their bodies are com-
posed of an apparently structureless animal substance of an
albuminous nature ("sarcode"), of a gelatinous consistence,
transparent, and exhibiting numerous minute granules or
rounded particles. The body-substance cannot be said in

Fig. 25.— The animal of Nonionina, one of the Foraminifera, after the shell has been
removed by a weak acid; 6. Gromia, a single-chambered Foraminifer (after Schultze),
showing the shell surrounded by a network of filaments derived from the body substance.

itself to possess any definite form, except in so far as it may
be bounded by a shell; but it has the power, wherever it may
be exposed, of emitting long thread-like filaments ("pseudo-
podia"), which interlace with one another to form a network
(fig. 25, b). These filaments can be thrown out at will, and

THE LAURENTTAN AND HURONIAN PERIODS. 73

to considerable distances, and can be again retracted into the
soft mass of the general body-substance, and they are the
agents by which the animal obtains its food. The soft bodies
of the Foraminifera are protected by a shell, which is usually

Tig. 26— Shells of living Foraminifera. a, Orbulina universa, In Its perfect condi-
tion, showing the tubular spines which radiate from the surface of the shell ; ft, Globi-
gerina bulloides, In its ordinary condition, the thin hollow spines which are attached
to the shell when perfect having been broken off ; c, Textularia variabilte ; d, Pener-
oplis planatus; e, Rotalia concamerata; /, Cristellaria subarcuatula. [Fig. a is
after Wyville Thomson; the others are after Williamson. All the figures are greatly
enlarged.]

calcareous, but may be composed of sand-grains cemented
together; and it may consist of a single chamber (fig. 26, a),
or of many chambers arranged in different ways (fig. 26, &-/).
Sometimes the shell has but one large opening into it — the
mouth; and then it is from this aperture that the animal pro-
trudes the delicate net of filaments with which it seeks its
food. In other cases the entire shell is perforated with
minute pores (fig. 26, e}, through which the soft body-substance
gains the exterior, covering the whole shell with a gelatinous
film of animal matter, from which filaments can be emitted at
any point. When the shell consists of many chambers, all of

74 HISTORICAL PALEONTOLOGY.

these are placed in direct communication with one another,
and the actual substance of the shell is often traversed by
minute canals filled with living matter (e.g., in Calcarina and
Nummulina). The shell, therefore, may be regarded, in such
cases, as a more or less completely porous calcareous structure,
filled to its minutest, internal recesses with the substance of
the living animals, and covered externally with a layer of the
same substance, giving off a network of interlacing filaments.

Such, in brief, is the structure of the living Foraminifera;
and it is believed that in Eozo'on we have an extinct example
of the same group, not only of special interest from its imme-
morial antiquity, but hardly less striking from its gigantic
dimensions. In its original condition, the entire chamber-
system of Eozoon is believed to have been filled with soft
structureless living matter, which passed from chamber to
chamber through the wide apertures connecting these cavities,
and from tier to tier by means of the tubuli in the shell-wall and
the branching canals in the intermediate skeleton. Through
the perforated shell-wall covering the outer surface the soft
body-substance flowed out, forming a gelatinous investment,
from every point of which radiated an interlacing net of deli-
cate filaments, providing nourishment for the entire colony.
In its present state, as before said, all the cavities originally
occupied by the body-substance have been filled with some
mineral substance, generally with one of the silicates of mag-
nesia; and it has been asserted that this fact militates strongly
against the organic nature of Eozoon, if not absolutely dis-
proving it. As a matter of fact, however — as previously no-
ticed— it is by no means very uncommon at the present day
to find the shells of living species of Foraminifera in which
all the cavities primitively occupied by the body-substance,
down to the minutest pores and canals, have been similarly
injected by some analogous silicate, such as glauconite.

Those, then, whose opinions on such a subject deservedly
carry the greatest weight, are decisively of opinion that we are
presented in the Eozoon of the Laurentian Rocks of Canada
with an ancient, colossal, and in some respects abnormal type
of the Foraminifera. In the words of Dr. Carpenter, it is not
pretended that " the doctrine of the Foraminiferal nature of
Eosoon can be proved in the demonstrative sense;" but it
may be affirmed " that the convergence of a number of separate
and independent probabilities, all accordant with that hypothesis,
while a separate explanation must be invented for each of

THE LAURENTIAN AND HURONIAN PERIODS. 75

them on any other hypothesis, gives it that high probability
on which we rest in the ordinary affairs of life, in the verdicts
of juries, and in the interpretation of geological phenomena
generally. "

It only remains to be added, that whilst Eozo'on is by far
the most important organic body hitherto found in the Lauren-
tian, and has been here treated at proportionate length, other
traces of life have been detected, which may subsequently
prove of great interest and importance. Thus, Principal
Dawson has recently described under the name of Archeeo-
spharina certain singular rounded bodies which he . has dis-
covered in the Laurentian limestones, and which he believes
to be casts of the shells of Foraminifera possibly somewhat
allied to the existing Globigerina. The same eminent palaeon-
tologist has also described undoubted worm-burrows from
rocks probably of Laurentian age. Further and more extended
researches, we may reasonably hope, will probably bring to
light other actual remains of organisms in these ancient deposits.
THE HURONIAN PERIOD.

The so-called Huronian Rocks, like the Laurentian, have
their typical development in Canada, and derive their name
from the fact that they occupy an extensive area on the borders
of Lake Huron. They are wholly metamorphic, and consist
principally of altered sandstones or quartzites, siliceous, fels-
pathic, or talcose slates, conglomerates, and limestones. They
are largely developed on the north shore of Lake Superior,
and give rise to a broken and hilly country, very like that
occupied by the Laurentians, with an abundance of timber,
but rarely with sufficient soil of good quality for agricultural
purposes. They are, however, largely intersected by mineral
veins, containing silver, gold, and other metals, and they will
ultimately doubtless yield a rich harvest to the miner. The
Huronian Rocks have been identified, with greater or less
certainty, in other parts of North America, and also in the
Old World.

The total thickness of the Huronian Rocks in Canada is
estimated as being not less than 18,000 feet, but there is con-
siderable doubt as to their precise geological position. In their
typical area they rest unconformably on the edge of strata of
Lower Laurentian age ; but they have never been seen in direct
contact with the Upper Laurentian, and their exact relations
to this series are therefore doubtful. It is thus open to question
whether the Huronian Rocks constitute a distinct formation, to

76 HISTORICAL PALEONTOLOGY.

be intercalated in point of time between the Laurentian and the
Cambrian groups ; or whether, rather, they should not be con-
sidered as the metamorphosed representatives of the Lower
Cambrian Rocks of other regions.

As regards the fossils of the Huronian Rocks, little can be
said, some of the specimens of Eosoon Canadense which have
been discovered in Canada are thought to come from rocks
which are probably of Huronian age. In Bavaria, Dr. Gumbel
has described a species of Eozoon under the name of EozoVn
Bavaricum, from certain metamorphic limestones which he
refers to the Huronian formation. Lastly, the late Mr. Billings
described, from rocks in Newfoundland apparently referable to
the Huronian, certain problematical limpet-shaped fossils, to
which he gave the name of Aspidclla.
LITERATURE.

Amongst the works and memoirs which the student may
consult with regard to the Laurentian and Huronian deposits
may be mentioned the following :* —

(1) 'Report of Progress of the Geological Survey of Canada

from its Commencement to 1863, ' pp. 38-49, and pp.
50-66.

(2) ' Manual of Geology. ' Dana. 2nd Ed. 1875.

(3) 'The Dawn of Life.' J. W. Dawson. 1876.

(4) " On the Occurrence of Organic Remains in the Lauren-

tian Rocks of Canada. " Sir W. E. Logan. ' Quart.
Journ. Geol. Soc., ' xxii. 45-50.

(5) " On the Structure of Certain Organic Remains in the

Laurentian Limestones of Canada. " J. W. Dawson.
'Quart. Journ. Geol Soc.,' xxi. 51-59.

(6) " Additional Note on the Structure and Affinities of

Eozoon Canadense. " W. B. Carpenter. ' Quart. Journ.
Geol. Soc., ' xxi. 59-66.

(7) " Supplemental Notes on the Structure and Affinities of

Eozoon Canadense. " W. B. Carpenter. ' Quart. Journ.
Geol. Soc., xxi. 219-228.

(8) " On the So-Called Eozoonal Rocks. " King & Rowney.

' Quart. Journ. Geol. Soc., ' xxii. 185-218.

(9) ' Chemical and Geological Essays. ' Sterry Hunt.

The above list only includes some of the more important
memoirs which may be consulted as to the geological and chem-
ical features of the Laurentian and Huronian Rocks, and as

* In this and in all subsequently following bibliographical lists, not
only is the selection of works and memoirs quoted necessarily extremely
limited ; but only such have, as a general rule, been chosen for mention as
are easily accessible to students who are in the position of being able to
refer to a good library. Exceptions, however, are occasionally made to
this rule, in favor of memoirs or works of special historical interest. It
is also unnecessary to add that it has not been thought requisite to insert
in these lists the well-known handbooks of geological and palaeontological
science, except in such instances as where they contain special information
on special points.

THE LAURENTIAN AND HURON IAN PERIODS. 77

to the true nature of Eozoon. Those who are desirous of study-
ing the later phases of the controversy with regard to Eozo'on
must consult the papers of Carpenter, Carter, Dawson, King &
Rowney, Hahn, and others, in the ' Quart. Journ. of the Geo-
logical Society, ' the ' Proceedings of the Royal Irsh Academy, '
the ' Annals of Natural History, ' the ' Geological Magazine. ' &c.
Dr. Carpenter's 'Introduction to the Study of the Foraminifera '
should also be consulted.

CHAPTER VIII.
THE CAMBRIAN PERIOD.

The traces of life in the Laurentian period, as we have seen,
are but scanty; but the Cambrian Rocks — so called from their
occurrence in North Wales and its borders ("Cambria") — have
yielded numerous remains of animals and some dubious plants.
The Cambrian deposits have thus a special interest as being
the oldest rocks in which occur any number of well-preserved
and unquestionable organisms. We have here the remains of
the first fauna, or assemblage of animals, of which we have at
present knowledge. As regards their geographical distribution,
the Cambrian Rocks have been recognized in many parts of
the world, but there is some question as to the precise limits
of the formation, and we may consider that their most typical
area is in* South Wales, where they have been carefully worked
out chiefly by Dr. Henry Hicks. In this region, in the neigh-
borhood of the promontory of St. David's, the Cambrian Rocks
are largely developed, resting upon an ancient ridge of Pre-
Cambrian (Laurentian?) strata, and overlaid by the lowest
beds of the Lower Silurian. The subjoined sketch-section
(fig. 27) exhibits in a general manner the succession of strata
in this locality.

From this section it will be seen that the Cambrian
Rocks in Wrales are divided in the first place into a lower and
an upper group. The Lower Cambrian is constituted at the
base by a great series of grits, sandstones, conglomerates, and
slates, which are known as the " Longmynd group, " from their
vast development in the Longmynd Hills in Shropshire, and
which attain in North Wales a thickness of 8000 feet or more.
The Longmynd beds are succeeded by the so-called " Mene-
vian group, " a series of sandstones, flags, and grits, about 600
feet in thickness, and containing a considerable number of
fossils. The Upper Cambrian series consists in its lower por-
tion of nearly 5000 feet of strata, principally shaly and slaty,

HISTORICAL PALEONTOLOGY.

which are known as the " Lingula Flags, " from the great
abundance in them of a shell referable to the genus Lingula.
These are followed by 1000 feet of dark shales and flaggy
sandstones, which are known as the " Tremadoc slates, " from
their occurrence near Tremadoc in North Wales; and these
in turn are surmounted, apparently quite conformably, by the
basement beds of the Lower Silurian.

GENERALIZED SECTION OF THE CAMBRIAN ROCKS IN WALES.
Fig. 27.

Arenig Group (Base of
the Lower Silurian).

Tremadoc Slates.

Upper Lingula Flags.
Middle Lingula Flags.

Lower Lingula Flags.
Menevian Group.

Longmynd or Harlech
Group.

Pre-Catnbrian Rocks.

THE CAMBRIAN PERIOD.

79

The opposite may be regarded as giving a typical series of
the Cambrian Rocks in a typical locality; but strata of Cambrian
age are known in many other regions, of which it is only
possible here to allude to a few of the most important. In
Scandinavia occurs a well-developed series of Cambrian de-
posits, representing both the lower and upper parts of the
formation. In Bohemia, the Upper Cambrian, in particular,
is largely developed, and constitutes the so-called " Primordial
zone " of Barrande. Lastly, in North America, whilst the Lower
Cambrian is only imperfectly developed, or is represented by
the Huronian, the Upper Cambrian formation has a wide ex-
tension, containing fossils similar in character to the analogous
strata in Europe, and known as the " Potsdam Sandstone. "
The subjoined table shows the chief areas where Cambrian
Rocks are developed, and their general equivalency :

TABULAR VIEW OF THE CAMBRIAN FORMATION.

Britain.

Europe.

America.

a. Tremadoc Slates.

a. Primordial zone

a. Potsdam

of Bohemia.

Sandstone.

Upper H

b. I«ingula Flags.

b. Paradoxides

b. Acadian

Cambrian.

Schists, Olenus
Schists,and Dict-

group of New
Brunswick.

yonema schists

of Sweden.

Huronian For-

a. I,ongmynd Beds.

a. Fucoidal Sand-
stone of Sweden.

mation ?

b. Uanberis Slates.

b. Eophyton Sand-

stone of Sweden.

c. Harlech Grits.

I,ower 4

d. Oldhamia Slates of

Cambrian.

Ireland.

e. Conglomerates and
Sandstones of

Sutherlandshire?

f. Menevian Beds.

Like all the older Palaeozoic deposits, the Cambrian Rocks,
though by no means necessarily what would be called actually
" metamorphic, " have been highly cleaved, and otherwise altered
from their original condition. Owing partly to their indurated
state, and partly to their great antiquity, they are usually found
in the heart of mountainous districts, which have undergone
great disturbance, and have been subjected to an enormous
amount of denudation. In some cases, as in the Longmynd
Hills in Shropshire, they form low rounded elevations, largely
covered by pasture, and with few or no elements of sublimity.
In other cases, however, they rise into bold and rugged

80 HISTORICAL PALEONTOLOGY.

mountains, girded by precipitous cliffs. Industrially, the Cam-
brian Rocks are of interest, if only for the reason that the
celebrated Welsh slates of Llanberis are derived from highly-
cleaved beds of this age. Taken as a whole, the Cambrian
formation is essentially composed of arenaceous and muddy
sediments, the latter being sometimes red, but more commonly
nearly black in color. It has often been supposed that the Cam-
brians are a deep-sea deposit, and that we may thus account
for the few fossils contained in them ; but the paucity of fossils
is to a large extent imaginary, and some of the Lower Cambrian
beds of the Longmynd Hills would appear to have been laid
down in shallow water, as they exhibit rain-prints, sun-cracks,
and ripple-marks — incontrovertible evidence of their having
been a shore-deposit. The occurrence of innumerable worm-
tracks and burrows in many Cambrian strata is also a proof of
shallow-water conditions ; and the general absence of limestones,
coupled with the coarse mechanical nature of many of the sedi-
ments of the Lower Cambrian, may be taken as pointing in the
same direction.

The life of the Cambrian, though not so rich as in the suc-
ceeding Silurian period, nevertheless consists of representa-
tives of most of the great classes of invertebrate animals. The
coarse sandy deposits of the formation, which abound more
particularly toward its lower part, naturally are to a large
extent barren of fossils; but the muddy sediments, when not
too highly cleaved, and especially towards the summit of the
group, are replete with organic remains. This is also the case,
in many localities at any rate, with finer beds of the Potsdam
Sandstone in America. Limestones are known to occur in
only a few areas (chiefly in America), and this may account for
the apparent total absence of corals. It is, however, interest-
ing to note that, with this exception, almost all the other lead-
ing groups of Invertebrates are known to have come into
existence during the Cambrian period.

Of the land-surfaces of the Cambrian period we know
nothing; and there is, therefore, nothing surprising in the fact
that our acquaintance with the Cambrian vegetation is confined
to some marine plants or sea-weeds, often of a very obscure and
problematical nature. The " Fucoidal Sandstone " of Sweden,
and the " Potsdam Sandstone " of North America, have both
yielded numerous remains which have been regarded as mark-
ings left by sea-weeds or " Fucoids ; " but these are highly enig-
matical in their characters, and would, in many instances, seem

THE CAMBRIAN PERIOD. 81

to be rather referable to the tracks and burrows of marine
worms. The first-mentioned of these formations has also
yielded the curious, furrowed and striated stems which have
been described as a kind of land-plant under the name of
Eophyton (fig. 28). It cannot be said, however, that the vege-

Fig. 28.— Fragment of Eophyton Linneanum, a supposed land-plant, Lower
Cambrian, Sweden, of the natural size.

table origin of these singular bodies has been satisfactorily
proved. Lastly, there are found in certain green and purple
beds of Lower Cambrian age at Bray Head, Wicklow, Ireland,
some very remarkable fossils, which are well known under the
name of Oldhainia, but the true nature of which is very doubtful.
The commonest form of Oldhamia (fig. 29) consists of a
thread-like stem or axis, from which spring at regular intervals
bundles of short filamentous branches in a fan-like manner.
6

82

HISTORICAL PALEONTOLOGY.

In the locality where it occurs, the fronds of Oldhamia are very
abundant, and are spread over the surfaces of the strata in
tangled layers. That it is organic is certain, and that it is a
calcareous sea-weed is probable; but it may possibly belong to
the sea-mosses (Polyzoa), or to the sea-firs (Sertularians).

Amongst the lower forms of animal life (Protozoa^, we find
the Sponges represented by the curious bodies, composed of
netted fibres, to which the name of Protospongia has been given
(fig. 32, a) ; and the comparatively gigantic, conical, or cylin-
drical fossils termed Archceocyathus by Mr. Billings are certainly
referable either to the Foraminifera or to the Sponges. The
almost total absence of lime-
stones in the formation may
be regarded as a sufficient ex-
planation of the fact that the
Foraminifera are not more
largely and unequivocally rep-
resented; though the exist-
ence of greensands in the
Cambrian beds of Wisconsin
and Tennessee may be taken
as an indication that this class
of animals was by no means
wholly wanting. The same
fact may explain the total ab-
sence of corals, so far as at
present known.

The group of the Eichi-
nodermaia (Sea-lilies, Sea-
urchins, and their allies) is
represented by a few forms,

which are principally of interest as being the earliest-known
examples of the class. It is also worthy of note that these
precursors of a group which subsequently attains such geo-
logical importance, are referable to no less than three distinct
orders — the Crinoids or Sea-lilies, represented by a species of
Deiidrocrinus; the Cystideans by Protocystites; and the Star-
fishes by Palasterina and some other forms. Only the last
of these groups, however, appears to occur in the Lower
Cambrian.

The Ringed-worms (Annelida}, if rightly credited with all
the remains usually referred to them, appear to have swarmed
in the Cambrian seas. Being soft-bodied, we do not find the

Fig. 29.— A portion of Oldhamia an-
tiqua, Lower Cambrian, Wicklow, Ire-
land, of the natural size. (AfterSalter.)

THE CAMBRIAN PERIOD. 83

actual worms themselves in the fossil condition, but we have,
nevertheless, abundant traces of their existence. In some
cases we find vertical burrows of greater or less depth, often
expanded towards their apertures, in which the worm must
have actually lived (fig. 30), as various species do at the pres-

Fig. 30.— Annelide-burrows (Scolitfiua linearis), from the Potsdam Sandstone
of Canada, of the natural size. (After Billings.)

ent day. In these cases, the tube must have been rendered
more or less permanent by receiving a coating of mucus, or
perhaps a genuine membraneous secretion, from the body of
the animal, and it may be found quite empty, or occupied by
a cast of sand or mud. Of this nature are the burrows which
have been described under the names of Scolithus and Scoleco-
derma, and probably the Histioderma of the Lower Cambrian
of Ireland. In other cases, as in Arenicolites (fig. 32, &), the
worm seems to have inhabited a double burrow, shaped like
the letter U, and having two openings placed close together
on the surface of the stratum. Thousands of these twin-
burrows occur in some of the strata of the Longmynd, and it
is supposed that the worm used one opening to the burrow as
an aperture of entrance, and the other as one of exit. In other
cases, again, we find simply the meandering trails caused by
the worm dragging its body over the surface of the mud.
Markings of this kind are commoner in the Silurian Rocks,
and it is generally more or less doubtful whether they may
not have been caused by other marine animals, such as shell-

84 HISTORICAL PALAEONTOLOGY.

fish, whilst some of them have certainly nothing whatever to
do with the worms. Lastly, the Cambrian beds often show
twining cylindrical bodies, commonly more or less matted
together, and not confined to the surfaces of the strata, but
passing through them. These have often been regarded as
the remains of sea-weeds, but it is more probable that they
represent casts of the underground burrows of worms of simi-
lar habits to the common lob-worm (Arenicola) of the present
day.

The Articulate animals are numerously represented in the
Cambrian deposits, but exclusively by the class of Crustaceans.
Some of these are little double-shelled creatures, resembling
our living water-fleas (Ostracoda). A few are larger forms, and
belong to the same group as the existing brine-shrimps and
fairy-shrimps (Phyllopoda). One of the most characteristic of
these is the Hyvnenocaris vermicauda of the Lingula Flags (fig.
32, d). By far the larger number of the Cambrian Crustacea
belong, however, to the remarkable and wholly extinct group
of the Trilobites. These extraordinary animals must have
literally swarmed in the seas of the later portion of this and
the whole of the succeeding period; and they survived in
greatly diminished numbers till the earlier portion of the
Carboniferous period. They died out, however, wholly before
the close of the Palaeozoic epoch, and we have no Crusta-
ceans at the present day which can be considered as their
direct representatives. They have, however, relationships of
a more or less intimate character with the existing groups of
the Phyllopods, the King-crabs (Limulus}, and the Isopods
("Slaters," Wood-lice, &c.) Indeed, one member of the last-
mentioned order, namely, the Serolis of the coasts of Patagonia,
has been regarded as the nearest living ally of the Trilobites.
Be this as it may, the Trilobites possessed a, skeleton which,
though capable of undergoing almost endless variations, was
wonderfully constant in its pattern of structure, and we may
briefly describe here the chief features of this.

The upper surfaces of the body of a Trilobite was defended
by a strong shell or " crust, " partly horny and partly calcare-
ous in its composition. This shell (fig. 31) generally exhibits
a very distinct " trilobation " or division into three longitudinal
lobes, one central and two lateral. It also exhibits a more
important and more fundamental division into three transverse
portions, which are so loosely connected with one another as
very commonly to be found separate. The first and most

THE CAMBRIAN PERIOD.

anterior of these divisions is a shield or buckler which covers
the head; the second or middle portion is composed of mov-
able rings covering the trunk ("thorax"); and the third is a
shield which covers the tail or " abdomen. " The head-shield
(fig. 31, e) is generally more or less semicircular in shape; and
its central portion, covering the stomach of the animal, is usu-
ally strongly elevated, and generally marked by lateral furrows.
A little on each side of the head are placed the eyes, which
are generally crescentic in shape, and resemble the eyes of
insects and many existing Crustaceans in being " compound, "
or made up of numerous simple eyes aggregated together.
So excellent is the state of preservation of many specimens of
Trilobites, that the numerou0 individual lenses of the eyes
have been uninjured, and as many as four hundred have been
counted in each eye of some forms. The eyes may be sup-
ported upon prominences, but they are never carried on mov-

Fig. 31.— Cambrian Trilobites: a, Paradoxidea Bohemicua, reduced In size; 6, Elllp-
socephalus Hoffl; c, Sao fiirsuta; d, Conocorypfie Sultzeri (all the above, together with
fig. g, are from the Upper Cambrian or "Primordial Zone" of Bohemia); e. Head-shield
of Dikelloccphalua Celticus, from the Llngula Flags of Wales;/, Head-shield of Cono-
coryphe Matthewi, from the Upper Cambrian (Acadian Group) of New Brunswick; g,
Affnostus rex, Bohemia; h, Tail-shield of Dikellocephalus M Innesotensis , from the
Upper Cambrian (Potsdam Sandstone) of Minnesota. (After Barrande, Dawson, Salter,
and Dale Owen.)

86 HISTORICAL PALEONTOLOGY.

able stalks (as they are in the existing lobsters and crabs) ; and
in some of the Cambrian Trilobites, such as the little Agnosti
(fig. 31, g), the animal was blind. The lateral portion of the
head-shield are usually separated from the central portion by
a peculiar line of division (the so-called " facial suture ") on
each side ; but this is also wanting in some of the Cambrian
species. The backward angles of the head-shield, also, are
often prolonged into spines, which sometimes reach a great
length. Following the head-shield behind, we have a portion
of the body which is composed of movable segments or "body-
rings, " and which is technically called the " thorax. " Ordi-
narily, this region is strongly trilobed, and each ring consists of
a central convex portion, and of two flatter side-lobes. The
number of body-rings in the thorax is very variable (from two
to twenty-six), but is fixed for the adult forms of each group of
the Trilobites. The young forms have much fewer rings than
the rull-grown ones; and it is curious to find that the Cam-
brian Trilobites very commonly have either a great many rings
(as in Paradoxides, fig. 31, a), or else very few (as in Agnostus,
fig- 31* d)- In some instances, the body-rings do not seem to
have been so constructed as to allow of much movement, but
in other cases this region of the body is so flexible that the
animal possessed th^ power of rolling itself up completely, like
a hedgehog; and many individuals have been permanently
preserved as fossils in this defensive condition. Finally, the
body of the Trilobite was completed by a tail-shield (technic-
ally termed the "pygidium"), which varies much in size and
form, and is composed of a greater or less number of rings,
similar to those which form the thorax, but immovably amalga-
mated with one another (fig. 31, 7i).

The under surface of the body in the Trilobites appears to
have been more or less entirely destitute of hard structures,
with the exception of a well-developed upper lip, in the form
of a plate attached to the inferior side of the head-shield in
front. There is no reason to doubt that the animal possessed
legs; but these structures seem to have resembled those of
many living Crustaceans in being quite soft and membranous.
This, at any rate, seems to have been generally the case ;
though structures which have been regarded as legs have been
detected on the under surface of one of the larger species of
Trilobites. There is also, at present, no direct evidence that
the Trilobites possessed two pairs of jointed feelers ("an-
tennae") which are so characteristic of recent Crustaceans.

THE CAMBRIAN PERIOD. 87

The Trilobites vary much in size, and the Cambrian forma-
tion presents examples of both the largest and the smallest
members of the order. Some of the young forms may be little
bigger than a millet-seed, and some adult examples of the
smaller species (such as Agnostus) may be only a few lines in
length; whilst such giants of the order as Paradoxides and
Asaphus may reach a length of from one to two feet. Judging
from what we actually know as to the structure of the Trilo-
bites, and also from analogous recent forms, it would seem that
these ancient Crustaceans were mud-haunting creatures, deni-
zens of shallow seas, and affecting the soft silt of the bottom
rather than the clear water above. Whenever muddy sedi-
ments are found in the Cambrian and Silurian formations,
there we are tolerably sure to find Trilobites, though they are
by no means absolutely wanting in limestones. They appear
to have crawled about upon the sea-bottom, or burrowed in the
yielding mud, with the soft under surface directed downwards ;
and it is probable that they really derived their nutriment from
the organic matter contained in the ooze amongst which they
lived. The vital organs seem to have occupied the central lobe
of the skeleton, by which they were protected; and a series of
delicate leaf-like paddles, which probably served as respiratory
organs, would appear to have been carried on the under surface
of the thorax. That they had their enemies may be regarded
as certain; but we have no evidence that they were furnished
with any offensive weapons, or, indeed, with any means of
defence beyond their hard crust, and the power, possessed by
so many of them, of rolling themselves into a ball. An addi-
tional proof of the fact that they for the most part crawled
along the sea-bottom is found in the occurrence of tracks and
markings of various kinds, which can hardly be ascribed to
any other creatures with any show of probability. That this,
is the true nature of some of the markings in question cannot
be doubted at all ; and in other cases no explanation so prob-
able has yet suggested. If, however, the tracks which
have been described from the Potsdam Sandstone of North
America under the name of Protichnites are really due to the
peregrinations of some Trilobite, they must have been pro-
duced by one of the largest examples of the order.

As already said, the Cambrian Rocks are very rich in the
remains of Trilobites. In the lowest beds of the series (Long-
mynd Rocks), representatives of some half-dozen genera have
now been detected, including the dwarf Agnostus and the giant

88

HISTORICAL PALAEONTOLOGY.

Paradoxides. In the higher beds, the number both of genera
and species is largely increased ; and from the great compara-
tive abundance of individuals, the Trilobites have every right
to be considered as the most characteristic fossils of the Cam-
brian period, — the more so as the Cambrian species belong to
peculiar types, which, for the most part, died out before the
commencement of the Silurian epoch.

All the remaining Cambrian fossils which demand any notice
here are members of one or other division of the great class
of the Mollusca, or " Shell-fish " properly so called. In the
Lower Cambrian Rocks the Lamp-shells (Brachiopoda} are the
principal or sole representatives of the class, and appear chiefly
in three interesting and important types— namely, Lingulella,

Fig. 32.— Cambrian Fossils: a, Protospongia fenestrata, Menevian Group; b, Areni-
colites didymus, Longmynd Group ; c, Lingulella ferruginea, Longmynd and Mene-
vian, enlarged; d, Hymenocaris vermicauda, Lingula Flags; e. Lingulella Davisii,
Lingula Flags; /, Orthis lenticularis, Lingula Flags; g, Theca Davidii, Tremadoc
Slates; h, Modiolopsis Solvensis,TTein&&oc Slates; i, Obolclla sagittalis, interior of valve,
Menevian ;.?, Exterior of the same; k, Orthis Hicksii, Menevian; I, Cast of the same;
m, Olenut micrurus, Lingula Flags. (After Salter, Hicks and Davidson.)

Discina, and Obolella. Of these the last (fig. 32, «) is highly
characteristic of these ancient deposits ; whilst Discina is one
of those remarkable persistent types which, commencing at
this early period, has continued to be represented by varying
forms through all the intervening geological formations up to
the present day. Lingulella (fig. 32, c), again, is closely allied

THE CAMBRIAN PERIOD.

to the existing "Goose-bill" Lamp-shell (Lingula anatina), and
thus presents us with another example of an extremely long-
lived type. The Lingulellce and their successors, the Lingula,
are singular in possessing a shell which is of a horny texture,
and contains but a small proportion of calcareous matter. In
the Upper Cambrian Rocks, the Lingulella become much more
abundant, the broad satchel-shaped species known as L. Davisii
(fig. 32, e) being so abundant that one of the great divisions of
the Cambrian is termed the " Lingula Flags. " Here, also, we
meet for the first time with examples of the genus Orthis (fig. 32, /,
k, /) a characteristic Palaeozoic type of the Brachiopods, which is
destined to undergo a vast extension in later ages.

Of the higher groups of the Mollusca the record is as yet
but scanty. In the Lower Cambrian, we have but the thin,
fragile, dagger-shaped shells of the free-s\vimming oceanic
Molluscs or "Winged-snails" (Pteropoda), of which the most
characteristic is the genus Theca (fig. 32, g). In the upper
Cambrian, in addition to these, we have a few Univalves
(Gasteropoda), and, thanks to the researches of Dr. Hicks,
quite a small assemblage of Bivalves (Lamellibranchiata),
though these are mostly of no great dimensions (fig. 32, h).
Of the chambered Cephalopoda (Cuttle-fishes and their allies),
we have but few traces, and these wholly confined to the higher
beds of the formation. We meet, however, with examples of
the wonderful genus Orthoceras, with its
straight, partitioned shell, which we shall
find in an immense variety of forms in the
Silurian rocks. Lastly, it is worthy of
note that the lowest of all the groups of
the Mollusca — namely, that of the Sea-
mats, Sea-mosses, and Lace-corals (Poly-
zoa) — is only doubtfully known to have
any representatives in the Cambrian,
though undergoing a large and varied
development in the Silurian deposits.

An exception, however, may with
much probability be made to this state-
ment in favor of the singular genus
Dictyoncma (fig. 33), which is highly
characteristic of the highest Cambrian beds
(Tremadoc Slates). This curious fossil
occurs in the form of fan-like or funnel-
shaped expansions, composed of slightly-diverging horny

Fig. 33.— Fragment of
Dictyonema sociale, con-
siderably enlarged, show-
Ing the horny branches,
with their connecting
cross-bars, and with a row
of cells on each side.
(Original.)

90 HISTORICAL PALEONTOLOGY.

branches, which are united in a net-like manner by numerous
delicate cross-bars, and exhibit a row of little cups or cells, in
which the animals were contained, on each side. Dictyonema
has generally been referred to the Graptolites; but it has a much
greater affinity with the plant-like Sea-firs (Sertularians) or the
Sea-mosses (Polysoa), and the balance of evidence is perhaps
in favor of placing it with the latter.

LITERATURE.

The following are the more important and accessible works
and memoirs which may be consulted in studying the strati-
graphical and palaeontological relations of the Cambrian
Rocks :—

(1) 'Siluria. ' Sir Roderick Murchison. 5th ed., pp. 21-46.

(2) 'Synopsis of the Classification of the British Palaeozoic

Rocks. ' Sedgwick. Introduction to the 3d Fasciculus
of the ' Descriptions of British Palaeozoic Fossils in the
Woodwardian Museum, ' By F. M'Coy, pp. i-xcviii,
1855.

(3) ' Catalogue of the Cambrian and Silurian Fossils in the

Geological Museum of the University of Cambridge. '
Salter. With a Preface by Prof. Sedgwick. 1873.

(4) 'Thesaurus Siluricus. ' Bigsby. 1868.

(5) " History of the Names Cambrian and Silurian. " Sterry

Hunt. — ' Geological Magazine. ' 1873.

(6) ' Systeme Silurien du Centre de la Boheme. ' Barrande.

Vol. I.

(7) ' Report of Progress of the Geological Survey of Canada,

from its Commencement to 1863, ' pp. 87-109.

(8) 'Acadian Geology.' Dawson. Pp. 641-657.

(9) " Guide to the Geology of New York, " Lincklaen ; and

" Contributions to the Palaeontology of New York, "
James Hall. — ' Fourteenth Report on the State Cabinet. '
1861.

(10) 'Palaeozoic Fossils of Canada.' Billings. 1865.

(n) 'Manual of Geology.' Dana. Pp. 166-182. 2nd ed.
1875-

(12) "Geology of North Wales," Ramsay; with Appendix on

the Fossils, Salter. — ' Memoirs of the Geological Sur-
vey of Great Britain, ' vol. iii, 1866.

(13) " On the Ancient Rocks of the St. David's Promontory,

South Wales, and their Fossil Contents. " Harkness
and Hicks. — ' Quart. Journ. Geol. Soc., ' xxvii. 384-
402. 1871.

THE CAMBRIAN PERIOD. 91

(14) "On the Tremadoc Rocks in the Neighborhood of St.
David's, South Wales, and their Fossil Contents. "
Hicks. — ' Quart Journ. Geol. Soc., ' xxix. 39-52 1873.

In the above list, allusion has necessarily been omitted to num-
erous works and memoirs on the Cambrian deposits of Sweden
and Norway, Central Europe, Russia, Spain, and various parts
of North America, as well as to a number of important papers
on the British Cambrian strata by various well-known observers.
Among these latter may be mentioned memoirs by Prof. Phillips,
and Messrs Salter, Hicks, Belt, Plant, Homfray, Ash, Holl, &c.

CHAPTER IX.

THE LOWER SILURIAN PERIOD.

The great system of deposits to which Sir Roderick Murchi-
son applied the name of " Silurian Rocks " reposes directly
upon the highest Cambrian beds, apparently without any
marked unconformity, though with a considerable change in
the nature of the fossils. The name " Silurian " was originally
proposed by the eminent geologist just alluded to for a great
series of strata lying below the Old Red Sandstone, and occu-
pying districts in Wales and its borders which were at one
time inhabited by the " Silures, " a tribe of ancient Britons.
Deposits of a corresponding age are now known to be largely
developed in other parts of England, in Scotland, and in Ire-
land, in North America, in Australia, in India, in Bohemia,
Saxony, Bavaria, Russia, Sweden and Norway, Spain, and in
various other regions of less note. In some regions, as in the
neighborhood of St. Petersburg, the Silurian strata are found
not only to have preserved their original horizontality, but also
to have retained almost unaltered their primitive soft and inco-
herent nature. In other regions, as in Scandinavia and many
parts of North America, similar strata, now consolidated into
shales, sandstones, and limestones, may be found resting with
a very slight inclination on still older sediment. In a great
many regions, however, the Silurian deposits are found to have
undergone more or less folding, crumpling, and dislocation,
accompanied by induration and " cleavage " of the finer and

92 HISTORICAL PALAEONTOLOGY.

softer sediments ; whilst in some regions, as in the Highlands
of Scotland, actual " metamorphism " has taken place. In
consequence of the above, Silurian districts usually present
the bold, rugged, and picturesque outlines which are char-
acteristic of the older " Primitive " rocks of the earth's crust in
general. In many instances, we find Silurian strata rising into
mountain-chains of great grandeur and sublimity, exhibiting
the utmost diversity of which rock-scenery is capable, and de-
lighting the artist with endless changes of valley, lake, and
cliff. Such districts are little suitable for agriculture, though
this is often compensated for by the valuable mineral products
contained in the rocks. On the other hand, when the rocks are
tolerably soft and uniform in their nature, or when few disturb-
ances of the crust of the earth have taken place, we may find
Silurian areas to be covered with an abundant pasturage or to
be heavily timbered.

Under the head of " Silurian Rocks, " Sir Roderick Murchi-
son included all the strata between the summit of the " Long-
mynd " beds and the Old Red Sandstone, and he divided these
into the two great groups of the Lower Silurian and Upper Silu-
rian. It is, however, now generally admitted that a considerable
portion of the basement beds of Murchison's Silurian series
must be transferred — if only upon palseontological grounds — to
the Upper Cambrian, as has here been done; and much contro-
versy has been carried on as to the proper nomenclature of the
Upper Silurian and of the remaining portion of Murchison's
Lower Silurian. Thus, some would confine the name " Silu-
rian " exclusively to the Upper Silurian, and would apply the
name of " Cambro-Silurian " to the Lower Silurian, or would
include all beds of the latter age in the " Cambrian " series of
Sedgwick. It is not necessary to enter into the merits of these
conflicting views. For our present purpose, it is sufficient to
recognize that there exist two great groups of rocks between
the highest Cambrian beds, as here defined, and the base of
the Devonian or Old Red Sandstone. These two great groups
are so closely allied to one another, both physically and palae-
ontologically, that many authorities have established a third
or intermediate group (the "Middle Silurian"), by which a pas-
sage is made from one into the other. This method of pro-
cedure involves disadvantages which appear to outweigh its
advantages; and the two groups in question are not only gen-
erally capable of very distinct stratigraphical separation, but at
the same time exhibit, together with the alliances above spoken

THE LOWER SILURIAN PERIOD. 93

of, so many and such important palaeontological differences,
that it is best to consider them separately. We shall there-
fore follow this course in the present instance; and pending
the final solution of the controversy as to Cambrian and Silu-
rian nomenclature, we shall distinguish these two groups of
strata as the " Lower Silurian " and the " Upper Silurian. "

The Lower Silurian Rocks are known already to be devel-
oped in various regions; and though their general succession
in these areas is approximately the same, each area exhibits
peculiarities of its own, whilst the subdivisions of each are
known by special names. All, therefore, that can be attempted
here, is to select two typical areas — such as Wales and North
America — and to briefly consider the grouping and divisions
of the Lower Silurian in each.

In Wales, the line between the Cambrian and Lower Silurian
is somewhat ill-defined, and is certainly not marked by any
strong unconformity. There are, however, grounds for accept-
ing the line proposed, for paLneontological reasons, by Dr.
Hicks, in accordance with which the Tremadoc Slates ("Lower
Tremadoc " of Salter) become the highest of the Cambrian
deposits of Britain. If we take this view, the Lower Silurian
rocks of Wales and adjoining districts are found to have the
following general succession from below upwards (fig. 34) : —

1. The Arenig Group. — This group derives its name from
the Arenig mountains, where it is extensively developed. It
consists of about 4000 feet of slates, shales, and flags, and is
divisible into a lower, middle, and upper division, of which the
former is often regarded as Cambrian under the name of
" Upper Tremadoc Slates. "

2. The Llandeilo Group. — The thickness of this group varies
from about 4000 to as much as 10,000 feet; but in this latter
case a great amount of the thickness is made up of volcanic
ashes and interbedded traps. The sedimentary beds of this
group are principally slates and flags, the latter occasionally
with calcareous bands; and the whole series can be divided
into a lower, middle, and upper . Llandeilo division, of which
the last is the most important. The name of " Llandeilo " is
derived from the town of the same name in Wales, where strata
of this age were described by Murchison.

3. The Caradoc or Bala Group. — The alternative names of
this group are also of local origin, and are derived, the one

94 HISTORICAL PALEONTOLOGY.

from Caer Caradoc in Shropshire, the other from Bala in Wales,
strata of this age occurring in both localities. The series is
divided into a lower and upper group, the latter chiefly com-
posed of shales and flags, and the former of sandstones and
shales, together with the important and interesting calcareous
band known as the " Bala Limestone. " The thickness of the
entire series varies from 4000 to as much as 12,000 feet, ac-
cording as it contains more or less of interstratified igneous
rocks.

4. The Llandovery Group (Lower Llandovery of Murchi-
son). — This series, as developed near the town of Llandovery, in
Caermarthenshire, consists of less than 1000 feet of conglom-
erates, sandstones, and shales. It is probable, however, that
the little calcareous band known as the " Hirnant Limestone, "
together with certain pale-colored slates which lie above, the
Bala Limestone, though usually referred to the Caradoc series,
should in reality be regarded as belonging to the Llandovery
group.

The general succession of the Lower Silurian strata of
Wales and its borders, attaining a maximum thickness (along
with contemporaneous igneous matter) of nearly 30,000 feet, is
diagramatically represented in the annexed sketch-section (fig.
34):-

[ GENERALIZED SECTION

THE LOWER SILURIAN PERIOD.

95

GENERALIZED SECTION OF THE LOWER SILURIAN ROCKS
OF WALES.

Fig. 34-

May Hill Sandstone
(base of Upper Silu-
rian).

Llandovery Group.

Upper Bala.

Lower Bala.

Upper Llandeilo.
Middle Llandeilo.
Lower Llandeilo.

Upper Arenig.

Middle Arenig.

f Lower Arenig (Up-
•I per Tremadoc
[ Group).

f Tremadoc Slates
j (Lower Tremadoc
Group).

In North America, both in the United States and in Can-
ada, the Silurian rocks are very largely developed, and may be
regarded as constituting an exceedingly full and typical series

96 HISTORICAL PALEONTOLOGY.

of the deposits of this period. The chief groups of the Silurian
rocks of North America are as follows, beginning, as before,
with the lowest strata, and proceeding upwards (fig. 35) : —

1. Quebec Group. — This group is typically developed in the
vicinity of Quebec, where it consists of about 5000 feet of
strata, chiefly variously-colored shales, together with some
sandstones and a few calcareous bands. It contains a number
of peculiar Graptolites, by which it can be identified without
question with the Arenig group of Wales and the correspond-
ing Skiddaw Slates of the North of England. It is also to be
noted that numerous Trilobites of a distinct Cambrian fades
have been obtained in the limestones of the Quebec group,
near Quebec. These fossils, however, have been exclusively
obtained from the limestones of the group; and as these lime-
stones are principally calcareous breccias or conglomerates,
there is room for believing that these primordial fossils are
really derived, in part at any rate, from fragments of an upper
Cambrian limestone. In the State of New York, the Grapto-
litic shales of Quebec are wanting; and the base of the Silurian
is constituted by the so-called " Calciferous Sand-rock" and
" Chazy Limestone. " * The first of these is essentially and
typically calcareous, and the second is a genuine limestone.

2. The Trenton Group. — This is an essentially calcareous
group, the various limestones of which it is composed being
known as the " Bird's-eye, " " Black River, " and " Trenton "
Limestones, of which the last is the thickest and most impor-
tant. The thickness of this group is variable, and the bands of
limestone in it are often separated by beds of shale.

3. The Cincinnati Group (Hudson River Formation f). —
This group consists essentially of a lower series of "shales, often
black in color and highly charged with bituminous matter
(the " Utica Slates"), and of an upper series of shales, sand-
stones, and limestones (the "Cincinnati" rocks proper). The
exact parallelism of the Trenton and Cincinnati groups with,

* The precise relations of the Quebec shales with Graptolites (Levis
Formation) to the Calciferous and "Chazy beds are still obscure, though
there seems little doubt but that the Quebec Shales are superior to the
Calciferous Sand-rock.

t There _is some difficulty about the precise nomenclature of this group.
It was originally called the " Hudson River Formation ;" but this name
is inappropriate, as rocks of this age hardly touch anywhere the actual
Hudson River itself, the rocks so called formerly being now known to be
of more ancient date. There is also some want of propriety in the name
of " Cincinnati Group," since the rocks which are known under this name
in^ the vicinity _ of Cincinnati itself are the representatives of the Trenton
Limestone, Utica Slates, and the Old Hudson River group, inseparably
united in what used to be called the " Blue Limestone Series."

THE LOWER SILURIAN PERIOD.

97

the subdivisions of the Welsh Silurian series can hardly be
stated positively. Probably no precise equivalency exists;
but there can be no doubt but that the Trenton and Cincin-
nati groups correspond, as a whole, with the Llandeilo and
Caradoc groups of Britain. The subjoined diagrammatic
section (fig. 35) gives a general idea of the succession of the
Lower Silurian rocks of North America : —

GENERALIZED SECTION OF THE LOWER SILURIAN ROCKS
OF NORTH AMERICA.

Fig. 35-

Medina Sandstone (base of
Upper Silurian).

— Cincinnati Group proper.

Utica Slates.
Trenton Limestone.

Black River Limestone.
Bird's-eye Limestone.
Chazy Limestone.

| Quebec Shales (Levis Beds),

Calciferous Sand-rock.

— Potsdam Sandstone.

98 HISTORICAL PALEONTOLOGY.

Of the life of the Lower Silurian period we have record in a
vast number of fossils, showing that the seas of this period
were abundantly furnished with living denizens. We have,
however, in the meanwhile, no knowledge of the land-surfaces
of the period. We have therefore no means of speculating
as to the nature of the terrestial animals of this ancient age,
nor is anything known with certainty of any land-plants which
may have existed. The only relics of vegetation upon which
a positive opinion can be expressed belong to the obscure
group of the " Fucoids, " and are supposed to be the remains
of sea-weeds. Some of the fossils usually placed under this
head are probably not of a vegetable nature at all, but others

Fig. 36. — LicropJiycua Ottawctensis, a " Fucoid," from the Trenton Limestone
(Lower Silurian) of Canada. (After Billings.)

(fig. 36) appear to be unquestionable plants. The true affin-
ities of these, however, are extremely dubious. All that can
be said is, that remains which appear to be certainly vegetable,

THE LOWER SILURIAN PERIOD.

99

and which are most probably due to marine plants, have been
recognized nearly at the base of the Lower Silurian (Arenig),
and that they are found throughout the series whenever suitable
conditions recur.

The Protozoans appear to have flourished extensively in the
Lower Silurian seas, though to a large extent under forms
which are still little understood. We have here for the first
time the appearance of Foraminifera of the ordinary type — one
of the most interesting observations in this connection being
that made by Ehrenberg, who showed that s the lower Silurian
sandstones of the neighborhood of St. Petersburg contained
casts in glauconite of Foraminiferous shells, some of which are
referable to the existing genera Rotalia and Textularia. True
Sponges, belonging to that section of the group in which the
skeleton is calcareous, are also not unknown, one of the most

characteristic genera being As-
tylospongia (fig. 37). In this
genus are included more or less
globular, often lobed sponges,
which are believed not to have
been attached to foreign bodies.
In the form here figured there
is a funnel-shaped cavity at the
summit ; and the entire mass of
the sponge is perforated, as in
living examples, by a system
of canals which convey the
sea-water to all parts of the
prcemona, cut organism. The canals by
which the sea-water gains en-
Tennessee. (After Ferdinand Rceiner.) trance open on the exterior of

the sphere, and those by which

it again escapes from the sponge open into the cup-shaped
depression at the summit.

The most abundant, and at the same time the least under-
stood, of Lower Silurian Protozoans belonging, however, to the
genera. Stromatopora and Receptaculites, the structure of which
can merely be alluded to here. The specimens of Stromato-
pora (fig. 38) occur as hemispherical, pear-shaped, globular, or
irregular masses, often of very considerable size, and some-
times demonstrably attached to foreign bodies. In their struc-
ture these masses consist of numerous thin calcareous laminae,
usually arranged concentrically, and separated by narrow

ioo HISTORICAL PALEONTOLOGY.

interspaces. These interspaces are generally crossed by
numerous vertical calcareous pillars, giving the vertical section

Fig. 38 — A small and perfect specimen of Stromatopora rugosa, of the natural
size, from the Trenton Limestone of Canada. (After Billings.)

of the fossil a lattice-like appearance. There are also usually
minute pores in the concentric laminae, by which the successive
interspaces are placed in communication; and sometimes the
surface presents large rounded openings, which appear to corre-
spond with the water-canals of the Sponges. Upon the whole,
though presenting some curious affinities to the calcareous
Sponges, Stromatopora is perhaps more properly regarded as
a gigantic Foraminifer. If this view be correct, it is of special
interest as being probably the nearest ally of Eozoon, the
general appearance of the two being strikingly similar, though
their minute structure is not at all the same. Lastly, in the
fossils known as Receptaculites and Ischadites we are also pre-
sented with certain singular Lower Silurian Protozoans, which
may with great probability be regarded as gigantic Foraminif-
era. Their structure is very complex; but fragments are
easily recognized by the fact that the exterior is covered with
numerous rhomboidal calcareous plates, closely fitting together,
and arranged in peculiar intersecting curves, presenting very
much the appearance of the engine-turned case of a watch.

THE LOWER SILURIAN PERIOD. 101

Passing next to the sub-kingdom of Ccelenterate animals
(Zoophytes, Corals, &c.), we find that this great group, almost
or wholly absent in the Cambrian, is represented in Lower
Silurian deposits by a great number of forms belonging on the
one hand to the true Corals, and on the other hand to the
singular family of the Graptolites. If we except certain plant-
like fossils which probably belong rather to the Sertularians
or the Polyzoans (e.g., Dictyonema, Dendrograptus, &c.)> the
family of the Graptolites may be regarded as exclusively
Silurian in its distribution. Not only is this the case, but it
attained its maximum development almost upon its first ap-
pearance, in the Arenig Rocks ; and whilst represented by a
great variety of types in the Lower Silurian, it only exists in
the Upper Silurian in a much diminished form. The Grap-
tolites (Gr. grapho, I write; lithos, stone) were so named by
Linnaeus, from the resemblance of some of them to written or
pencilled marks upon the stone, though the great naturalist him-
self did not believe them to be true fossils at all. They occur
as linear or tleaf-like bodies, sometimes simple, sometimes com-
pound and branched; and no doubt whatever can be enter-
tained as to their being the skeletons of composite organisms,
or colonies of semi-independent animals united together by
a common fleshy trunk, similar to what is observed in the
colonies of the existing Sea-firs (Sertularians). This fleshy
trunk or common stem of the colony was protected by a deli-
cate horny sheath, and it gave origin to the little flower-like
" polypites, " which constituted the active element of the whole
assemblage. These semi-independent beings were, in turn,
protected each by a little horny cup or cell, directly connected
with the common sheath below, and terminating above in an
opening through which the polypite could protrude its tentacled
head or could again withdraw itself for safety. The entire
skeleton, again, was usually, if not universally, supported by
a delicate horny rod or " axis, " which appears to have been
hollow, and which often protrudes to a greater or less extent
beyond one or both of the extremities of the actual colony.

The above gives the elementary constitution of any Grapto-
lite, but there are considerable differences as to the manner in
which these elements are arranged and combined. In some
forms the common stem of the colony gives origin to but a
single row of cells on one side. If the common stem is a
simple, straight, or slightly-curved linear body, then we have
the simplest form of Graptolite known (the genus Monograptus} ;

102 HISTORICAL PALEONTOLOGY.

and it is worthy of note that these simple types do not come
into existence till comparatively late (Llandeilo), and last
nearly to the very close of the Upper Silurian. In other
cases, whilst there is still but a single row of cells, the colony
may consist of two of these simple stems springing from a
common point, as in the so-called " twin Graptolites " (Didy-
mograptus, fig. 40). This type is entirely confined to the earlier

portion of the Lower Silu-
rian period (Arenig and
Llandeilo). In other cases,
again, there may be four
of such stems springing
from a central point. (Tet-
ragraptus). Lastly, there
are numerous complex
forms (such as Dichograp-
tus, Loganograptus, &c.) in
which there are eight or
more of these simple bran-
ches, all arising from a
common center (fig. 39),
which is sometimes fur-
nished with a singular
horny disc. These com-
plicated branching forms,
as well as the Tetragrapti,
are characteristic of the
horizon of the Arenig
group. Similar forms, of-
ten specifically identical,

Fig. 39. — Dichograptus octobracMatus,'& branched, "unicellular" Grapto/lte from
the Skiddaw and Quebec Groups (Arenig). (After Hall.)

are found at this horizon in Wales, in the great series of the
Skiddaw Slates of the north of England, in the Quebec group
in Canada, in equivalent beds in Sweden, and in certain gold-
bearing slates of the same age in Victoria in Australia.

THE LOWER SILURIAN PERIOD.

103

In another great group of Graptolites (including the genera
Diplograptus, Dicranograptus, Climacograptus, &c.) the common
stem of the colony gives origin, over part or the whole of its

Fig. 40.— Central portion of the colony of Didymograptus divaricatus, Upper
Llandeilo, Dumfriesshire. (Original.)

length, to two rows of cells, one on each side (fig. 41). These
" double-celled " Graptolites are highly characteristic of the

Fig. 41. — Examples of Diplograptus Fig. 42.— Group of individuals of Phyllo-

prtetis, showing variations in the append- graptus typus, from the Quebec group of

ages at the base. Upper Llandeilo, Canada. (After Hall.) One of the four rows

Dnmfreisshire. (Original.) of cells is hidden on the under surface.

Lower Silurian deposits; and, with an exception more appar-

104 HISTORICAL PALEONTOLOGY.

ent than real in Bohemia, they are exclusively confined to
strata of Lower Silurian age, and are hot known to occur in
the Upper Silurian. Lastly, there is a group of Graptolites
(Phyllograptus, fig. 42) in which the colony is leaf-like in form,
and is composed of four rows of cells springing in a cross-like
manner from the common stem. These forms are highly char-
acteristic of the Arenig group.

The Graptolites are usually found in dark-colored, often
black shales, which sometimes contain so much carbon as to
become " anthracitic. " They may be simply carbonaceous ;
but they are more commonly converted into iron-pyrites, when
they glitter with the brilliant luster of silver as they lie scattered
on the surface of the rock, fully deserving in their metallic
tracery the name of " written stones. " They constitute one
of the most important groups of Silurian fossils, and are of the
greatest value in determining the precise stratigraphical posi-
tion of the beds in which they occur. They present, however,
special difficulties in their study; and it is still a moot point as
to the precise position in the zoological scale. The balance
of evidence is in favor of regarding them as an ancient and
peculiar group of the Sea-firs (Hydroid Zoophytes), but some
regard them as belonging rather to the Sea-mosses (Polyzoa).
Under any circumstances, they cannot be directly compared
either with the ordinar}' Sea-firs or the ordinary Sea-mosses ;
for these two groups consist of fixed organisms, whereas the
Graptolites were certainly free-floating creatures, living at
large in the open sea. The only Hydroid Zoophytes or Poly-
zoans which have a similar free mode of existence, have either
no skeleton at all, or have hard structures quite unlike the
horny sheaths of the Graptolites.

The second great group of Coelenterate animals (Actinozoa}
is represented in the Lower Silurian rocks by the numerous
Corals. These, for obvious reasons, are much more abundant
in regions where the Lower Silurian series is largely calcareous
(as in North America) than in districts like Wales, where
limestones are very feebly developed. The Lower Silurian
Corals, though the first of their class, and presenting certain
peculiarities, may be regarded as essentially similar in nature
to existing Corals. These, as is well known, are the calcareous
skeletons of animals — the so-called " Coral - Zoophytes " —
closely allied to the common Sea-anemones in structure and
habit. A simple coral (fig. 43) consists of a calcareous cup
embedded in the soft tissues of the flower-like polype, and hav-

THE LOWER SILURIAN PERIOD.

105

ing at its summit a more or less deep depression (the "calice")
in which the digestive organs are contained. The space within
the corals is divided into compartments by numerous vertical
calcareous plates (the "septa"), which spring from the inside
of the wall of the cup, and of which some generally reach the

Fig. 43.— Zaphrentls Stokesi, a simple Fig. 44.— Upper surface of a mass of
" cup-coral," Upper Silurian, Canada. Slrornbodes pentagonus, Upper Silurian,
(After Billings.) Canada. (After Billings.)

center. Compound corals, again (fig. 44), consist of a greater
or less number of structures similar inx structure to the above,
but united together in different ways into a common mass.
Simple corals, therefore, are the skeletons of single and inde-
pendent polypes; whilst compound corals are the skeletons of
assemblages or colonies of similar polypes, living united with
one another as an organic community.

In the general details of their structure, the Lower Silurian
Corals do not differ from the ordinary Corals of the present
day. The latter, however, have the vertical calcareous plates
of the coral ("septa") arranged in multiples of six or five;
whereas the former have these structures arranged in multiples
of four, and often showing a cross-like disposition. For this
reason, the common Lower Silurian Corals are separated to
form a distinct group under the name of Rugose Corals or
Rugosa. They are further distinguished by the fact that the
cavity of the coral ("visceral chamber") is usually subdivided
by more or less numerous horizontal calcareous plates or

io6 HISTORICAL PALEONTOLOGY.

partitions, which divide the coral into so many tiers or storeys,
and which are known as the " tabulae " (fig. 45).

In addition to the Rugose Corals, the Lower Silurian rocks
contain a number of curious compound corals, the tubes
of which have either no septa at all or merely rudimentary
ones, but which have the transverse partitions or " tabulae "
very highly developed. These are known as the Tabulate

Fig. ±5.—Columnaria alveolata, a Rugose compound coral, with Imperfect septa, but
having the corallites partitioned off into storeys by "tabulae." Lower Silurian,
Canada. (After Billings . )

Corals; and recent researches on some of their existing allies
(such as Helioporajhave shown that they are really allied to
the modern Sea-pens, Organ-pipe Corals, and Red Coral,
rather than to the typical stony Corals. Amongst the charac-
teristic Rugose Corals of the Lower Silurian may be mentioned
species belonging to the genera Columnaria, Favistella, Strep-
telasma, and Zaphrentis; whilst amongst the " Tabulate "
Corals, the principal forms belong to the genera Chatetes,
Halysites (the Chain-coral), Constellaria, and Heliolites. These
groups of the Corals, however, attain a greater development
at a later period, and they will be noticed more particularly
hereafter.

Passing on to higher animals, we find that the class of the
Echinodermata is represented by examples of the Star-fishes
(Asteroidea), the Sea-lilies (Crinoidea}, and the peculiar extinct
group of the Cystideans (Cystoidea}, with one or two of the
Brittle-stars (Ophiuroidea} — the Sea-urchins (Echinoidea} being
still wanting. The Crinoids, though in some places extremely
numerous, have not the varied development that they possess
in the Upper Silurian, in connection with which their structure
will be more fully spoken of. In the meanwhile, it is sufficient

THE LOWER SILURIAN PERIOD.

107

to note that many of the calcareous deposits of the Lower
Silurian are strictly entitled to the name of " Crinoidal lime-
stones, " being composed in great part of the detached joints,

Fig. 46.— Group of Cystideans. A, Caryocrinus ornatus* Upper Silurian, America;
B, Pleurocystites squamosus, showing two short " arms," Lower Silurian, Canada; C,
Pseudocrinm bifasciatua, Upper Silurian, England; D, Lepadocrinus Gebhardi,
Upper Silurian, America. (After Hall, Billings and Salter.)

and plates, and broken stems, of these beautiful but fragile
organisms (see fig. 12). Allied to the Crinoids are the singular
creatures which are known as Cystideans (fig. 46). These are
generally composed of a globular or ovate body (the "calyx"),
supported upon a short stalk (the "column"), by which the
organism was usually attached to some foreign body. The
body was enclosed by closely-fitting calcareous plates, accu-
rately jointed together; and the stem was made up of numerous
distinct pieces or joints, flexibly united to each other by mem-
brane. The chief distinction which strikes one in comparing
the Cystideans with the Crinoids is, that the latter are always
furnished, as will be subsequently seen, with a beautiful crown
of branched and feathery appendages, springing from the sum-

* The genus Caryocrinus is sometimes regarded as properly belonging
to the Crinoids, but there seem to be good reasons for rather considering
it as an abnormal form of Cystidean. •

io8

HISTORICAL PALAEONTOLOGY.

mit of the calyx, and which are composed of innumerable
calcareous plates or joints, and are known as the " arms. " In
the Cystideans, on the other hand, there are either no " arms "
at all, or merely short, unbranched, rudimentary arms. The
Cystideans are principally, and indeed nearly exclusively,

Fig. 47.— Lower Silurian Crustaceans, a, Asaphus tyrannus. Upper Llandeilo ; 6.
Ogygia Buchii, Upper Llandeilo ; c, Trinucleus concentricus, Caradoc ; d, Caryocaris
Wrigfitii, Arenig (Skiddaw Slates) ; e, Beyrichia complicata, natural size and enlarged,
Upper Llandeilo and Caradoc ; /, Primitia strangulata, Caradoc ; g, Head-shield of
Calymene Blumenbachii, var. brevicapitata, Caradoc ; h, Head-shield of Triarthrm
Becki (Utica Slates), United States ; i, Shield of LeperdiUa Canadensis, var. Joseph-
iana, of the natural size, Trenton Limestone, Canada; j, The same, viewed from the
front. (After Salter, M'Coy, Rupert Jones, and Dana.)

Silurian fossils ; and though occurring in the Upper Silurian
in no small numbers, they are pre-eminently characteristic of
the Llandeilo-Caradoc period of Lower Silurian time. They

THE LOWER SILURIAN PERIOD.

105

commenced their existence, so far as known, in the Upper
Cambrian ; and though examples are not absolutely unknown
in later periods, they are pre-eminently characteristic of the
earlier portion of the Palaeozoic epoch.

The Ringed Worms (Annelides} are abundantly represented
in the Lower Silurian, but principally by tracks and burrows
similar in essential respects to those which occur so commonly
in the Cambrian formation, and calling for no special com-
ment. Much more important are the Articulate animals, rep-
resented, as heretofore, wholly by the remains of the aquatic
group of the Crustaceans. Amongst these are numerous little
bivalved forms — such as species of Primitia (fig. 47 /), Bey-
richia (fig. 47, e), and Leperditia (fig. 47, i and /). Most of
these are very small, varying from the size of a pin's head up
to that of a hemp seed; but they are sometimes as large as
a small bean (fig. 47, 0, and they are commonly found in
myriads together in the rock. As before said, they belong to
the same great group as the living Water-fleas (Ostracoda).
Besides these, we find the pod-shaped head-shields of the
shrimp-like Phyllopods — such as Caryocaris (fig. 47, d) and
Ceratiocaris. More important, however, than any of these are
the Trilobites, which may be considered as attaining their maxi-

Fig. 48. — Ptilodictya falciformis. a,
Small specimen of the natural size ; 6,
Cross-section, showing the shape of the
front ; c. Portion of the surface, en-
larged, Trenton Limestone and Cincin-
nati Group, America. (Original.)

Fig. 49.— A, Ptilodictya acuta ; B, Ptil-
odictya Schafferi. or, Fragment, of the
natural size ; 6, portion, enlarged to
show the cells. Cincinnati Group of Ohio
and Canada. (Original.)

mum development in the Lower Silurian. The huge Paradoxides
of the Cambrian have now disappeared, and with them almost
all the principal and characteristic " primordial " genera, save
Olenus and Agnostus. In their place we have a great number

110

HISTORICAL PALEONTOLOGY.

of new forms — some of them, like the great Asaphus tyrannus
of the Upper Llandeilo (fig. 47, a), attaining a length of a foot
or more, and thus hardly yielding in the matter of size to their
ancient 'rivals. Almost every subdivision of the Lower Silurian
series has its own special and characteristic species of Trilq-
bites; and the study of these is therefore of great importance
to the geologist. A few widly-dispersed and characteristic

Fig. 50.— Lower Silurian Brachiopods. a. and a' Orthis biforata, Llandeilo-Cara-
doc, Britain and America ; 6, Orthis Jlabellulum, Caradoc, Britain ; c, Orthia sub-
quadrata, Cincinnati Group, America ; c' Interior of the dorsal valve of the same ; d,
Strophomena deltoidea, Llandeilo-Caradoc, Britain and America. (After Meek, Hall,
andSalter.)

species have been here figured (fig. 47) ; and the following
may be considered as the principal Lower Silurian genera —
Asaphus, Ogygia, Cheirurus, Awipyx, Calymene, Trinucleus,
Lichas, Illanus, JEglina, Harpes, Remopleurides, Phacops,
Acidaspis, and Homalonotus, a few of them passing upwards
under new forms into the Upper Silurian.

Coming next to the Mollusca, we find the group of the Sea-
mosses and Sea-mats (Polyzoa} represented now by quite a
number of forms. Amongst these are examples of the true
Lace-corals (Retepora and Fenestella}, with their netted fan-like
or funnel-shaped fronds ; and along with these are numerous
delicate encrusting forms, which grew parasitically attached to
shells and corals (Hippothoa, Alecto, &c.) ; but perhaps the
most characteristic forms belong to the genus Ptilodictya (figs.
48 and 49). In this group the frond is flattened, with thin

THE LOWER SILURIAN PERIOD.

in

striated edges, sometimes sword-like or scimitar-shaped, but
often more or less branched ; and it consists of two layers of
cells, separated by a delicate membrane, and opening upon
opposite sides. Each of these little chambers or " cells " was
originally tenanted by a minute animal, and the whole thus
constituted a compound organism or colony.

The Lamp-shells or Brachiopods are so numerous, and pre-
sent such varied types, both in this and the succeeding period
of the Upper Silurian, that the name of " Age of Brachiopods "
has with justice been applied to the Silurian period as a whole.
It would be impossible here to enter into details as to the
many different forms of Brachiopods which present themselves
in the Lower Silurian deposits ; but we may select the three
genera Orthis, Strophotnena, and Leptana for illustration, as
being specially characteristic of this period, though not exclu-
sively confined to it. The numerous shells which belong to
the extensive and cosmopolitan genus Orthis (fig. 50, a, b, c,

Fig. 51. — Lower Silurian Brachiopods. a, Strophomena alternata, Cincinnati Group,
America; b, Strophomena JiliteMa, Trenton and Cincinnati Groups, America ; c-, Or-
this tf,8tudinaria, Caradoc, Europe, and America ; d, d', Orthis plicatella, Cincinnati
Group, America ; e, e1, ef', Leptcena sencea, Llandeilo and Caradoc, Europe and
America. (After Meek, Hall, and the Author.)

and fig. 51, c and rf), are usually more or less transversely-
oblong or subquadrate, the two valves (as more or less in all
the Brachiopods) of unequal sizes, generally more or less con-
vex, and marked with radiating ribs or lines. The valves of
the shell are united to one another by teeth and sockets, and
there is a straight hinge-line. The beaks are also separated
by a distinct space ("hinge-area"), formed in part by each
valve, which is perforated by a triangular opening, through

112

HISTORICAL PALEONTOLOGY.

which, in the living condition, passed a muscular cord attach-
ing the shell to some foreign object. The genus Strophomena
(fig. 50, d, and 51, a and fr) is very like Ortliis in general char-
acter; but the shell is usually much flatter, one or other valve
often being concave, the hinge-line is longer, and the aperture
for the emission of the stalk of attachment is partially closed
by a calcareous plate. In Leptana, again (fig. 51, #), the shell
is like Strophomena in many respects, but generally compara-
tively longer, often completely semicircular, and having one
valve convex and the other valve concave. Amongst other
genera of Brachiopods which are largely represented in the
Lower Silurian rocks may be mentioned Lingula, Crania,
Discina, Trematis, Siphonotreta, Acrotreta, Rhynchonella, and
Athyris; but none of these can claim the importance to which
the three previously-mentioned groups are entitled.

The remaining Lower Silurian groups of Mollusca can be
but briefly glanced at here. The Bivalves (Lamellibranchiata)
find numerous representatives, belonging to such genera as
Modiolopsis, Ctenodonta, Orthonota, Palczarca, Lyrodesma, Am-
bonychia, and Cleidophorus. The Univalves (Gasteropoda) are
also very numerous, the two most important genera being
Murchisonia (fig. 52) and Pleurotomaria. In both these groups
the outer lip of the shell is notched ; but the shell
in the former is elongated and turreted, whilst in
the latter it is depressed. The curious oceanic
Univalves known as the Heteropods are also very
abundant, the principal forms belonging to Bel-
lerophon and Maclurea. In the former (fig. 53)
there is a symmetrical convoluted shell, like that
of the Pearly Nautilus in shape, but without any
internal partitions, and having the aperture of-
ten expanded and notched behind. The species
of Maclurea (fig. 54) are found both in North
America and in Scotland, and are exclusively
confined to the Lower Silurian period, so far
as known. They have the shell coiled into a
flat spiral, the mouth being furnished with a
very curious, thick, and solid lid or " opercu-
lum. " The Lower Silurian Pteropods, or "Wing-
ed Snails, " are numerous, and belong prin-
cipally to the genera Theca, Conularia, and
Tentaculites, the last-mentioned of these often being extremely
abundant in certain strata.

Tig. 52.— Mur-
chisoniagracili*,
Trenton Lime-
stone, America.
(After Billings.)

THE LOWER SILURIAN PERIOD. 113

Lastly, the Lower Silurian Rocks have yielded a vast num-
ber of chambered shells, referable to animals which belong
to the same great division as the Cuttle-fishes (the Cephalo-
poda), and of which the Pearly Nautilus is the only living
representative at the present day. In this group of Cephalopods
the animal possesses a well-developed external shell, which is
divided into chambers by shelly partitions ("septa"). The
animal lives in the last-formed and largest chamber of the

Fig. 53. — Different views of Bellerophon Argo, Trenton Limestone, Canada.
(After Billings.)

shell, to which it is organically connected by muscular attach-
ments. The head is furnished with long muscular processes or
" arms, " and can be protruded from the mouth of the shell at
will, or again withdrawn within it. We learn, also, from the
Pearly Nautilus, that these animals must have possessed two
pairs of breathing organs or " gills ; " hence all these forms are
grouped together under the name of the " Tetrabranchiate "

Fig. 54. — Different views of Machirea crenulata, Quebec Group, Newfoundland.
(After Billings. )

Cephalopods (Gr. tetra, four; branghia, gills). On the other hand,
the ordinary Cuttle-fishes and •Calamaries either possess an
8

H4

HISTORICAL PALEONTOLOGY.

internal skeleton, or if they have an external shell, it is not
chambered ; their " arms " are furnished with powerful organs
of adhesion in the form of suckers; and they possess only a
single pair of gills. For this last reason they are termed the
" Dibranchiate " Cephalopods (Gr. dis, twice ; branghia, gills). No
trace of the true Cuttle-fishes has yet been found in Lower
Silurian deposits; but the Tetrabranchiate group is represented

Fig. 55. — Fragment of Orthoceras cre-
briseptum, Cincinnati Group, North
America, of the natural size. The lower
figure is a section showing the air-cham-
bers, and the form and position of the
siphuncle. (After Billings.)

Fig. 56. — Restoration of Orthoceraa,
the shell being supposed to be divided
vertically, and only its upper part being
shown, a, Arms ; /, Muscular tube
("funnel") by which water is expelled
from the mantle-chamber ; c, Air-cham-
bers ; s, Siphuncle.

by a great number of forms, sometimes of great size. The prin-
cipal Lower Silurian genus is the well-known and widely-
distributed Orthoceras (fig. 55). The shell in this genus agrees
with that of the existing Pearly Nautilus, in consisting of num-

* This illustration is taken from a rough sketch made by the author
many years ago, but he is unable to say from what original source it was
copied.

THE LOWER SILURIAN PERIOD. 115

erous chambers separated by shelly partitions (or septa), the
latter being perforated by a tube which runs the whole length of
the shell after the last chamber, and is known as the " siphuncle "
(fig. 56, j). The last chamber formed is the largest, and in it
the animal lives. The chambers behind this are apparently filled
with some gas secreted by the animal itself ; and these are sup-
posed to act as a kind of float, enabling the creature to move
with ease under the weight of its shell. The various air-
chambers, though the siphuncle passes through them, have no
direct connection with one another ; and it is believed that the
animal has the power of slightly altering its specific gravity,
and thus of rising or sinking in the water by driving additional
fluid into the siphuncle or partially emptying it. The Ortho-
ceras further agrees with the Pearly Nautilus in the fact that
the partitions or septa separating the different air-chambers are
simple and smooth, concave in front and convex behind, and
devoid of the elaborate lobation which they exhibit in the
Ammonites; whilst the siphuncle pierces the septa either in
the center or near it. In the Nautilus, however, the shell is
coiled into a flat spiral ; whereas in Orthoceras the shell is
a straight, longer or shorter cone, tapering behind, and gradu-
ally expanding towards its mouth in front. The chief objec-
tions to the belief that the animal of the Orthoceras was essen-
tially like that of the Pearly Nautilus are — the comparatively
small size of the body-chamber, the often contracted aperture
of the mouth, and the enormous size of some specimens of
tjie shell. Thus, some Orthocerata have been discovered
measuring ten or twelve feet in length, with a diameter of a
foot at the larger extremity. These colossal dimensions cer-
tainly make it difficult to imagine that the comparatively small
body-chamber could have held an animal large enough to move
a load so ponderous as its own shell. To some, this difficulty
has appeared so great that they prefer to believe that the
Orthoceras did not live in its shell at all, but that its shell was
an internal skeleton similar to what we shall find to exist in
many of the true Cuttle-fishes. There is something to be said
in favor of this view, but it would compel us to believe in the
existence in Lower Silurian times of Cuttle-fishes fully equal
in size to the giant " Kraken " of fable. It need only be
added in this connection that the Lower Silurian rocks have
yielded the remains of many other Tetrabranchiate Cephalo-
pods besides Orthoceras. Some of these belong to Cyrtoceras,

n6 HISTORICAL PALAEONTOLOGY.

which only differs from Orthoceras in the bow-shaped form of
the shell ; others belong to Phragmoceras, Lituites, &c. ; and,
lastly, we have true Nautili, with their spiral shells, closely
resembling the existing Pearly Nautilus.

Whilst all the sub-kingdoms of the Invertebrate animals are
represented in the Lower Silurian rocks, no traces of Verte-
brate animals have ever been discovered in these ancient
deposits, unless the so-called " Conodonts " found by Pander
in vast numbers in strata of this age * in Russia should prove
to be really of this nature. These problematical bodies are of
microscopic size, and have the form of minute, conical, tooth-
shaped spines, with sharp edges, and hollow at the base.
Their original discoverer regarded them as the horny teeth
of fish allied to the Lampreys ; but Owen came to the con-
clusion that they probably belonged to Invertebrates. The
recent investigation of a vast number of similar but slightly
larger bodies, of very various forms, in the Carboniferous rocks
of Ohio, has led Professor Newberry to the conclusion that
these singular fossils really are, as Pander thought, the teeth of
Cyclostomatous fishes. The whole of this difficult question
has thus been reopened, and we may yet have to record the
first advent of Vertebrate animals in the Lower Silurian.

CHAPTER X.
THE UPPER SILURIAN PERIOD.

Having now treated of the Lower Silurian period at con-
siderable length, it will not be necessary to discuss the succeeding
group of the Upper Silurian in the same detail — the more so,
as with a general change of species the Upper Silurian animals
belong for the most part to the same great types as those which

* According to Pander, the " Conodonts " are found not only in the
Lower Silurian beds, but also in the " Ungulite Grit " (Upper Cambrian),
as well as in the Devonian and Carboniferous deposits of Russia. Should
the Conodonts prove to be truly the remains of fishes, we should thus have
to transfer the first appearance of Vertebrates to, at any rate, as early a
period as the Upper Cambrian.

THE UPPER SILURIAN PERIOD. 117

distinguish the Lower Silurian. As compared, also, as regards
the total bulk of strata concerned, the thickness of the Upper
Silurian is generally very much below that of the Lower Silurian,
indicating that they represent a proportionately shorter period
of time. In considering the general succession of the Upper
Silurian beds, we shall, as before, select Wales and America as
being two regions where these deposits are typically developed.
In Wales and its borders the general succession of the
Upper Silurian rocks may be taken to be as follows, in ascend-
ing order (fig. 57) :—

(1) The base of the Upper Silurian series is constituted by
a series of arenaceous beds, to which the name of " May Hill
Sandstone " was applied by Sedgwick. These are succeeded
by a series of greenish-grey or pale-grey slates ("Tarannon
Shales"), sometimes of great thickness; and these two groups
of beds together form what may be termed the "May Hill
Group" (Upper Llandovery of Murchison). Though not very
extensively developed in Britain, this zone is one very well
marked by its fossils ; and it corresponds with the " Clinton
Group " of North America, in which similar fossils occur. In
South Wales this group is clearly unconformable to the highest
member of the subjacent Lower Silurian (the Llandovery
group) ; and there is a reason to believe that a similar, though
less conspicuous, physical break occurs very generally between
the base of the Upper and the summit of the Lower Silurian.

(2) The Wenlock Group succeeds the May Hill group, and
constitutes the middle member of the Upper Silurian. At its
base it may have an irregular limestone (" Woolhope Lime-
stone"), and its summit may be formed by a similar but thicker
calcareous deposit ("Wenlock Limestone") ; but the bulk of the
group is made up of the argillaceous and shaly strata known as
the " Wenlock Shale. " In North Wales the Wenlock group is
represented by a great accumulation of flaggy and gritty strata
(the "Denbighshire Flags and Grits"), and similar beds (the
" Coniston Flags" and " Coniston Grits") take the same place
in the north of England.

(3) The Ludlow Group is the highest member of the Upper
Silurian, and consists typically of a lower arenaceous and shaly
series (the "Lower Ludlow Rock"), a middle calcareous
member (the " Aymestry Limestone"), and an upper shaly and
sandy series (the "Upper Ludlow Rock"), and " Downton Sand-
stone"). At the summit, or close to the summit, of the Upper

n8 HISTORICAL PALEONTOLOGY.

Ludlow, is a singular stratum only a few inches thick (vary-
ing from an inch to a foot), which contains numerous remains
of crustaceans and fishes, and is well known under the name
of the " bone-bed. " Finally, the Upper Ludlow rock graduates
invariably into a series of red sandy deposits, which, when of
a flaggy character, are known locally as the " Tile-stones. "
These beds are probably to be regarded as the highest member
of the Upper Silurian; but they are sometimes looked upon as
passage-beds into the Old Red Sandstone, or as the base of
this formation. It is, in fact, apparently impossible to draw
any actual line of demarcation between the Upper Silurian and
the overlying deposits of the Devonian or Old Red Sandstone
series. Both in Britain and in America the Lower Devonian
beds repose with perfect conformity upon the highest Silurian
beds, and the two formations appear to pass into one another
by gradual and imperceptible transition.

The Upper Silurian strata of Britain vary from perhaps
3000 or 4000 feet in thickness up to 8000 or 10,000 feet. In
North America the corresponding series, though also variable,
is generally of much smaller thickness, and may be under 1000
feet. The general succession of the Upper Silurian deposits
of North America is as follows : —

(1) Medina Sandstone. — This constitutes the base of the
Upper Silurian, and consists of sandy strata, singularly devoid
of life, and passing below in some localities into a conglo-
merate (" Oneida Conglomerate"), which is stated to contain
pebbles derived from the older beds, and which would thus
indicate an unconformity between the Upper and Lower
Silurian.

(2) Clinton Group. — Above the Medina sandstone are
beds of sandstone and shale, sometimes with calcareous bands,
which constitute what is known as the " Clinton Group. " The
Medina and Clinton groups are undoubtedly the equivalent of
the " May Hill Group " of Britain, as shown by the identity of
their fossils.

(3) Niagara Group. — This group consists typically of a
series of argillaceous beds ("Niagara Shale") capped by
limestone ("Niagara Limestone"); and the name of the
group is derived from the fact that it is over limestones of this
age that the Niagara river is precipitated to form the great
Falls. In places the Niagara group is wholly calcareous,
and it is continued upwards into a series of marls and sand-

THE UPPER SILURIAN PERIOD.

119

GENERALIZED SECTION OF THE UPPER SILURIAN STRATA
OF WALES AND SHROPSHIRE.

Fig. 57-

Base of Old Red Sand-
stone.

~- Pile-stones.

Upper Ludlow Rock.
Aymestry Limestone.

Lower Ludlow Rock.
Wenlock Limestone.

f Wenlock Shale (Den-
] bighshire Flags and
[ Grits of North Wales).

Woolhope Limestone.
Tarannon Shales.
May Hill Sandstone.

— Llandovery Rocks.

stones, with beds of salt and masses of gypsum (the " Salina
Group"), or into a series of magnesian limestones ("Guelph
Limestones"). The Niagara group, as a whole, corresponds
unequivocally with the Wenlock group of Britain.

(4) Lower Hcldcrbcrg Group. — The Upper Silurian period
in North America was terminated by the deposition of a series
of calcareous beds, which derive the name of "Lower Helder-
berg " from the Helderberg mountains, south of Albany, and
which are divided into several zones, capable of recognition by
their fossils, and known by local names (Tentaculite Lime-
stone, Water-lime, Lower Pentamerus Limestone, Delthyris

120 HISTORICAL PALEONTOLOGY.

Shaly Limestone, and Upper Pentamerus Limestone). As a
whole, this series may be regarded as the equivalent of the
Ludlow group of Britain, though it is difficult to establish any
precise parallelism. The summit of the Lower Helderberg
group is constituted by a coarse-grained sandstone (the " Oris-
kany Sandstone"), replete with organic remains, which have
to a large extent a Silurian fades. Opinions differ as to whether
this sandstone is to be regarded as the highest bed of the Upper
Silurian or the base of the Devonian. We thus see that in
, America, as in Britain, no other line than an artificial one can be
drawn between the Upper Silurian and the overlying Devonian.

As regards the life of the Upper Silurian period, we have, as
before, a number of so-called " Fucoids, " the true vegetable
nature of which is in many instances beyond doubt. In addition
to these, however, we meet for the first time, in deposits
of this age, with the remains of genuine land-plants, though
our knowledge of these is still too scanty to enable us to con-
struct any detailed picture of the terrestrial vegetation of the
period. Some of these remains indicate the existence of the
remarkable genus Lepidodendron — a genus which played a part
of great importance in the forests of the Devonian and Carbon-
iferous periods, and which may be regarded as a gigantic and
extinct type of the Club-mosses (Lycopodiacece}. Near the
summit of the Ludlow formation in Britain there have also
been found beds charged with numerous small globular bodies,
which Dr. Hooker has shown to be the seed-vessels or " spor-
angia" of Club-mosses. Principal Dawson further states that
he has seen in the same formation fragments of wood with the
structure of the singular Devonian Conifer known as Proto-
taxites. Lastly, the same distinguished observer has described
from the Upper Silurian of North America the remains of the
singular land-plants belonging to the genus Psilophyton, which
will be referred to at greater length hereafter.

The marine life of the Upper Silurian is in the main con-
stituted by types of animals similar to those characterizing the
Lower Silurian, though for the most part belonging to different
species. The Protozoans are represented principally by Stro-
matopora and Ischadites, along with a number of undoubted
sponges (such as Amphispongia, Astraospongia, Astylospongia,
and Palteoman on ) .

Amongst the Calenterates, we find the old group of Grap-
tolites now verging on extinction. Individuals still remain

THE UPPER SILURIAN PERIOD.

121

B

numerous, but the variety of generic and specific types has
now become greatly reduced. All the branching and complex
forms of the Arenig, the twin-Grap-
tolites and Dicranograpti of the
Llandeilo, and the double-celled
Diplograpti and Climacograpti of
the Bala group, have now disap-
peared. In their place we have
the singular Retiolites^with its curi-
ously-reticulated skeleton ; and sev-
eral species of the single-celled genus
Monograptus,oi which a character-
istic species (M. priodon) is here
figured. If we remove from this
group the plant-like Dictyonemee,
which are still present, and which
survive into the Devonian, no
known species of Graptolite has
hitherto been detected in strata
higher in geological position than
the Ludlow. This, therefore, pre-
sents us with the first instance we
have as yet met with of the total
disappearance and extinction of a
great and important series of or-
ganic forms.

The Corals are very numer-
ously represented in the Upper
Silurian rocks, some of the lime-
stones (such as the Wenlock Lime-
stone) being often largely composed of the skeletons of these
animals. Almost all the known forms of this period belong to
the two great divisions of the Rugose and Tabulate corals, the
former being represented by species of Zaphrentis, Omphyma,
Cystiphyllum, Strombodes, Acervularia, Cyathophyllum, &c. ;
whilst the later belong principally to the genera Favosites,
Chatctes, Halysites, Syringopora, Heliolites, and Plasmopora.
Amongst the Rugosa, the first appearance of the great and
important genus Cyathophyllum, so characteristic of the Palae-
ozoic period, is to be noted; and amongst the Tabulata we
have similarly the first appearance, in force at any rate, of the
widely - spread genus Favosites — the " Honeycomb - corals. "
The " Chain-corals " (Halysites}, figured below (fig. 59), are.

Fig. 58.— A, Monograptus prio-
don, slightly enlarged. B, Frag-
ment of the same viewed from be-
hind. C, Fragment of the same
viewed in front, showing the
mouths of the cellules. D, Cross-
section of the same. From the
Wenlock Group (Conlston Flags of
the North of England. ) (Original.)

122

HISTORICAL PALEONTOLOGY.

also very common examples of the Tabulate corals during this
period, though they occur likewise in the Lower Silurian.

Amongst the Echinodermata, all those orders which have
hard parts capable of ready preservation are more or less

d

Fig. 59.— a, Haly sites catenularia, small variety, of the natural size ; Fragment of
a large variety of the same, of the natural size ; c, Fragment of limestone with the
tubes of ffalysites agglomerata, of the natural size ; d, Vertical section of two tubes
of the same, showing the tabulae, enlarged. Niagara Limestone (Wenlock), Canada.
(Original.)

largely represented. We have no trace of the Holothurians
or Sea-cucumbers; but this is not surprising, as the record of
the past is throughout almost silent as to the former existence
of these soft-bodied creatures, the scattered plates and spicules
in their skin offering a very uncertain chance of preservation
in the fossil condition. The Sea-urchins (Echinoids) are said
to be represented by examples of the old genus Pal&chinus.
The Star-fishes (Asteroids) and the Brittle-stars (Ophiuroids)
are, comparatively speaking, largely represented, the former
by species of Palasterina (fig. 60), Palceaster (fig. 60), Palao-
coma (fig. 60), Petr aster, Gly 'piaster, and Lepidaster — and the
latter by species of Protaster (fig. 61), Palceodiscus, Acroura,
and Eucladia. The singular Cystideans, or "Globe Crinoids, "
with their globular or ovate, tesselated bodies (fig. 46, A, C, D,),
are also not uncommon in the Upper Silurian ; and if they do
not become finally extinct here, they certainly survive the close

THE UPPER SILURIAN PERIOD.

123

of this period by but a very brief time. By far the most im-
portant, however, of the Upper Silurian Echinoderms," are the

Fig. 60. — Upper Silurian Star-fishes. 1, Palasterina primceva- Lower Ludlow ; 2,
Palceaster Ruthveni Lower Ludlow; 3, Palceocoma Colvini, Lower Ludlow. (After
Salter.)

Sea-lilies or Crinoids. The Limestones of this period are often
largely composed of the fragmentary columns and detached
plates of these creatures, and some of them (such as the Wen-

rig. 61.— A, Protaster Sedgwickii, showing the disc and bases of the arms ; B, Por-
tion of an arm, greatly enlarged. Lower Ludlow. (After Salter. )

lock Limestone of Dudley) have yielded perhaps the most
exquisitely-preserved examples of this group with which we
are as yet acquainted. However varied in their forms, these
beautiful organisms consists of a globular, ovate, or pear-shaped
body (the "calyx"), supported upon a longer or shorter
jointed stem (or "column"). The body is covered externally
with an armour of closely-fitting calcareous plates (fig. 62), and
its upper surface is protected by similar but smaller plates

124

HISTORICAL PALEONTOLOGY.

more loosely connected by a leathery integument. From the
upper surface of the body, round its margin, springs a series
of longer or shorter flexible processes, composed of innu-
merable calcareous joints or pieces, movably united with one
another. The arms are typically five in number; but they
generally subdivide at least once, sometimes twice, and they
are furnished with similar but more slender lateral branches

Fig. G2.— Upper Silurian Crinoids. «, Calyx and arms of Eucalyptocrinua polydac-
tylus, Wenlock Limestone ; b, Ichthyocrinus Icevis, Niagara Limestone, America ; c,
Taxocrinus tuberculatus, Wenlock Limestone. (After M'Coy and Hall.)

or " pinnules, " thus giving rise to a crown of delicate feathery
plumes. The " column " is the stem by which the animal is
attached permanently to the bottom of the sea; and it is com-
posed of numerous separate plates, so jointed together that
whilst the amount of movement between any two pieces must
be very limited, the entire column acquires more or less flexi-
bility, allowing the organism as a whole to wave backwards and
forwards on its stalk. Into the exquisite minutice of structure
by which the innumerable parts entering into the composition
of a single Crinoid are adapted for their proper purpose in
the economy of the animal, it is impossible to enter here. No
period, as before said, has yielded examples of greater beauty
than the Upper Silurian, the principal genera represented
being Cyathocrinus, Platycrinus, Marsupiocrinus, Taxocrinus,

THE UPPER SILURIAN PERIOD.

125

Eucalyptocrinus, Ichthyocrinus, Mariacrinus, Periechocrinus,
Glyptocrinus, Crotalocrinus, and Edriocrinus.

The tracks and burrows of Annelides are as abundant in
the Upper Silurian strata as in older deposits, and have just
as commonly been regarded as plants. The most abundant
forms are the cylindrical, twisted bodies (Planolites), which are
so frequently found on the surfaces of sandy beds, and which
have been described as the stems of sea-weeds. These fossils
(fig. 63), however, can be nothing more, in most cases, than
the filled-up burrows of marine worms resembling the living
Lobe-worms. There are also various remains which belong to
the group of the tube-inhabiting Annelides (Tubicola). Of
this nature are the tubes of Serpulites and Cornulites, and the
little spiral discs of Spirorbis Lewisii.

Amongst the Articulates, we still meet only with the remains
of Crustaceans. Besides the little bivalved Ostracoda — which
here are occasionally found of the size of beans — and various

Fig. BS.—Planolites vulgaris, the fllled-up burrows of a marine worm.
Upper Silurian (Clinton Group), Canada (Original.)

Phyllopods of different kinds, we have an abundance of Trilo-
bites. These last-mentioned ancient types, however, are now
beginning to show signs of decadence; and though still indi-

126

HISTORICAL PALAEONTOLOGY.

vidually numerous, there is a great diminution in the number
of generic types. Many of the old genera, which flourished
so abundantly in Lower Silurian seas, have now died out;
and the group is represented chiefly by species of Cheirurus,
Encrinurus, Hordes, Proetus, Lichas, Acidaspis, Illanus, Caly-
mene{ Homalonotus, ?.nd Phacops — the last of these, one of the
highest and most beautiful of the groups of Trilobites, attaining
here its maximum of development. In the annexed illustra-
tion (fig. 64) some of the characteristic Upper Silurian Trilo-
bites are represented — all, however, belonging to genera which
have their commencement in the Lower Silurian period. In

Fig. 64. — Upper Silurian Trilobites. a, Cheirurus bimucronatus, Wenlock and
Caradoc ; 6, Phacops longicaudatus, Wenlock, Britain and America ; c, Phacopt
Downinglce, Wenlock and Ludlow ; d, Harpea ungula, Upper Silurian, Bohemia.
(After Salter and Barrande.)

addition to the above, the Ludlow rocks of Britain and the
Lower Helderberg beds of North America have yielded the
remains of certain singular Crustaceans belonging to the
extinct order of the Eurypterida. Some of these wonderful
forms are not remarkable for their size ; but others, such as
Pterygotus Anglicus (fig. 65), attain a length of six feet or more,
and may fairly be considered as the giants of their class. The
Eurypterids are most nearly allied to the existing King-crabs
(Lhnuli), and have the anterior end of the body covered with
a great head-shield, carrying two pairs of eyes, the one simple

THE UPPER SILURIAN PERIOD.

127

and the other compound. The feelers are converted into
pincers, whilst the last pair of limbs have their bases covered
with spiny teeth so as to act as jaws, and are flattened and
widened out towards their extremities so as to officiate as
swimming-paddles. The hinder extremity of the body is com-
posed of thirteen rings, which have no legs attached to them;
and the last segment of the tail is either a flattened plate or a
narrow, sword-shaped spine. Fragments of the skeleton are
easily recognized by the peculiar scale-like markings with
which the surface is adorned, and
which look not at all unlike the
scales of a fish. The most fa-
mous locality for these great Crus-
taceans is Lesmahagow, in Lan-
arkshire, where many different
species have been found. The
true King-crabs (Limuli} of exist-
ing seas also appear to have been
represented by at least one form
(Neolimulus} in the Upper Silu-
rian.

Coming to the Mollusca, we
note the occurrence of the same
great groups as in the Lower
Silurian. Amongst the Sea-
mosses (Polysoa}, we have the
ancient Lace-corals (Fenestella
and Retepora}, with the nearly-
allied Glauconome, and species of
Ptilodictya (fig. 66) ; whilst many
forms often referred here may
probably have to be transferred

tn the Cnrak incf as snmp sn Fis- 65> ~ Pterygotus Anglicv*,

orais, JUS viewed from the under side, reduced

called Corals will ultimately be in size and restored, c c, The feelers

(antennae), terminating in nipping-
removed to the present group. claws; oo, Eyes ;mm, Three pairs of
The TCrarViirmnHs rrmtirmpH jointed limbs, with pointed extremi-
ties ; n n, Swimming-saddles, the

to flourish during the Upper bases of which are spiny and act as
0., .... jaws. Upper Silurian, Lanarkshire,

bilunan period in immense num- (After Henry Woodward.)

bers and under a greatly in-
creased variety of forms. The three prominent Lower
Silurian genera Orthis, Strophomena, and Leptana are still
well represented, though they have lost their former pre-
eminence. Amongst the numerous types which have now

128

HISTORICAL PALAEONTOLOGY.

come upon the scene for the first time, or which have now a
special development, are Spirifera and Pentamerus. In the

Aa,

Fig. 66. — Upper Silurian Polyzoa. 1, Fan-shaped frond of Ehinopora verrucosa; la,
Portion of the surface of the same, enlarged ; 2 and 2a, Phcenopora ensifonnis, of the
natural size and enlarged ; 3 and 3a, Helopora fragilis, of the natural size and en-
larged ; 4 and 4«, Ptilodictya raripora, of the natural size and enlarged. The speci-
mens are all from the Clinton Formation (May Hill Group) of Canada. (Original.)

first of these (fig. 69, b, c), one of the valves of the shell (the
dorsal) is furnished in its interior with a pair of great calca-
reous spires, which served for the support of the long and

Fig. 67. — Spirifera hysterica. The right-hand figure shows the interior of the
dorsal valve, with the calcareous spires for the support of the arms.

fringed fleshy processes or " arms " which were attached to the
sides of the mouth. * In the genus Pentamerus (fig. 70) the
shell is curiously subdivided in its interior by calcareous
plates. The Pentameri commenced their existence at the very
close of the Lower Silurian (Llandovery), and survived to the

* In all the Lamp-shells the mouth is provided with two long fleshy
organs, which carry delicate filaments on their sides, and which are
usually coiled into a spiral. These organs are known as the " arms,"
and it is from their presence that the name of " BracJiiopoda " is derived
(Gr. brachion, arm; podes, feet). In some cases the arms are merely coiled
away within the shell, without any support; but in other cases they are
carried upon a more or less elaborate shelly loop, often ^spoken of as the
" carriage-spring apparatus." In the Sbirifers, and in other ancient
genera, this apparatus is coiled up into a complicated spiral (fig. 67). It
is these " arms," with or without the supporting loops or spires, which
serve as one of the special characters distinguishing the Brachiopods from
the true Bivalves (Lamcllibranchiata).

THE UPPER SILURIAN PERIOD.

129

close of the Upper Silurian ; but they are specially character-
istic of the May Hill and Wenlock groups, both in Britain

e

Fig. 68. — Upper Silurian Brachiopods. a a', Leptoccelia plano-convexa, Clinton
Group, America; b b', Rhynchonella neglecta, Clinton Group, America; e, Bhynchonella
cuneata, Niagara Group, America, and Wenlock Group, Britain ; d d', Orthls elegan-
tula, Llandeilo to Ludlow, America and Europe ; e ef, Atrypa fiemispherica, Clinton
Group, America, and Llandovery and May Hill Groups, Britain ; ff, Atrypa congesta,
Clinton Group. America ; g g', Orthls Davidsoni, Clinton Group, America. (After
Hall, Billings, and the Author. )

and in other regions. One species, Pentamerus galeatus, is
common to Sweden, Britain, and America. Amongst the

Fig. 69 — a, a' Meriitella intermedia, Niagara Group, America ; b, Spirifera Nlagar-
enste, Niagara Group, America ; c c', Spirifera crispa, May Hill to Ludlow, Britain,
and Niagara Group, America; d, Strophomena (Slreptorhynchiis} subplana, Niagara
Group, America ; e, Meristella naviformis, Niagara Group, America ; /, Meristella
cylindrica, Niagara Group, America. (After Hall, Billings, and the Author.)

remaining Upper Silurian Brachiopods are the extraordinary
Trimerellids; the old and at the same time modern Lingula,
Discing, and Crania; together with many species of Atrypa
9

130

HISTORICAL PALEONTOLOGY.

(fig. 68, e), Leptocoelia (fig. 68, a), Rhynchonella (fig. 68, b, c),
Meristella (fig. 69, a, e, /), Athyris, Reizia, Chonetes, &c.

Fig. lO.—Pentamerus Enightii, Wenlock and Ludlow. The right-hand
figure shows the internal partitions of the shell.

The higher groups of the Mollusca are also largely repre-
sented in the Upper Silurian. Apart from some singular types,
such as the huge and thick-shelled Megalomi of the American

11

im

c

Fig. 71. — Upper Silurian Bivalves, A, Cardiola interrupta, Wenlock and Ludlow ;
B, Pterinea subfalcata, Wenlock ; C, Cardiola flbrota, Ludlow. (After Salter and
M'Coy.)

Wenlock formation, the Bivalves (Lamellibranchiata} present
little of special interest ; for though sufficiently numerous, they
are rarely well preserved, and their true affinities are often un-
certain. Amongst the most characteristic genera of this period
may be mentioned Cardiola (fig. 71, A and C) and Pterinea, (fig.

71, B), though the latter survives to a much later date. The
Univalves (Gasteropoda) are very numerous, and a few charac-
teristic forms are here figured (fig. 72). Of these, no genus
is perhaps more characteristic than Euomphalus (fig. 72, b),
with its flat discoidal shell, coiled up into an oblique spiral,
and deeply hollowed out on one side ; but examples of this
group are both of older and of more modern date. Another
very extensive genus, especially in America, is Platyceras (fig.

72, a and /), with its thin fragile shell — often hardly coiled up
at all — its minute spire, and its widely-expanded, often sinuated
mouth. The British Acroculia should probably be placed

THE UPPER SILURIAN PERIOD.

131

here, and the group has with reason been regarded as allied
to the Violet-snails (lanthina) of the open Atlantic. The

Fig. 72.— Upper Silurian Gasteropoda, a, Platycerax ventricosum, Lower Hel-
derberg, America ; 6, Euomphalus discors, Wenlock, Britain ; c, Holopella obaoleta,
Ludlow, Britain ; d, Platyschisma lielicites, Upper Ludlow, Britain ; e, ffolopelia
gruc.il i nr, Wenlock, Britain ; /, Platyceras multisinuatum, Lower Helderberg,
America ; g, Holopea subconica, Lower Helderberg, America ; h, h' Platyostama
Niagarense, Niagara Group, America. (After Hall, M'Coy, and Salter.)

species of Platyostoma (fig. 72, h} also belong to the same
family ; and the entire group is continued throughout the
Devonian into the Carboniferous. Amongst other well-known
Upper Silurian Gasteropods are species of the genera Holopea
(fig. 72, g}, Holopella (fig. 72, <?), Platyschisma (fig. 72, rf),
Cyclonema, Pleurotomaria, Murchisonia, Trochonema, &c. The
oceanic Univalves (Heteropods) are rep-
resented mainly by species of Bellero-
phon; and the Winged Snails, or Ptero-
pods, can still boast of the gigantic Thecce
and Conularia, which characterize yet
older deposits. The commonest genus
of Pteropoda, however, is Tentaculites (fig.
73), which clearly belongs here, though
it has commonly been regarded as the
tube of an Annelide. The shell in this
group is a conical tube, usually adorned

with prominent transverse rings, and ri«- '3-— Tentacuiitea

. , .. ornatug. Upper Silurian of

often with finer transverse or longitudi- Europe and North America.

nal striae as well; and many beds of the

Upper Silurian exhibit myriads of such tubes . scattered promis-
cuously over their surfaces.

132

HISTORICAL PALAEONTOLOGY.

The last and highest group of the Mollusca — that of the
Cephalopoda — is still represented only by Tetr abranchiate
forms; but the abundance and variety of these is almost
beyond belief. Many hundreds of different species are known,
chiefly belonging to the straight Orthoceratites, but the slightly-
curved Cyrtoceras is only little less common. There are also
numerous forms of the genera Phragmoceras, Ascoceras, Gyro-
ceras, Lituites, and Nautilus. Here, also, are the first-known
species of the genus Goniatites — a group which attains con-
siderable importance in later deposits, and which is to be
regarded as the precursor of the Ammonites of the Secondary
period.

Finally, we find ourselves for the first time called upon to
consider the remains of undoubted vertebrate animals, in the
form of Fishes. The oldest of these remains, so far as yet
known, are found in the Lower Ludlow rocks, and they con-
sist of the bony head-shields or bucklers
of certain singular armored fishes belong-
ing to the group of the Ganoids, repre-
sented at the present day by the Stur-
geons, the Gar-pikes of North America,
and a few other less familar forms. The
principal Upper Silurian genus of these is
Pterasf>is,and the annexed illustration (fig.
74) will give some idea of the extraordi-
nary form of the shield covering the head
in these ancient fishes. The remarkable

Fig. 74.-Head-shield of stratum near the top of the Ludlow for-
Pterospis Banks li, Ludlow
rocks. (After Murchison.) mation known as the bone-bed has

also yielded the remains of shark-like
fishes. Some of these, for which the name

of Onchus has been proposed, are in the form of com-
pressed, slightly-curved spines (fig. 75, A), which would appear

Fig. 75. — A, Spine of Onchus tenuistriatua ; B, Shagreen-scales of Thelodus. Both
from the " bone-bed " of the Upper Ludlow rocks. (After Murchison. )

to be of the nature of the strong defensive spines implanted
in front of certain of the fins in many living fishes. Besides
these, have been found fragments of prickly skin or shagreen
(SpJiagodus}, along with minute cushion-shaped bodies (Thelo-

THE UPPER SILURIAN PERIOD. 133

dus, fig. 75, B), which are doubtless the bony scales of some
fish resembling the modern Dog-fishes. As the above mentioned
remains belong to two distinct, and at the same time highly-
organized, groups of the fishes, it is hardly likely that we are
really presented here with the first examples of this great class.
On the contrary, whether the so-called " Conodonts " should
prove to be the teeth of fishes or not, we are justified in ex-
pecting that unequivocal remains of this group of animals will
still be found in the Lower Silurian. It is interesting, also, to
note that the first appearance of fishes — the lowest class of
vertebrate animals — so far as known to us at present, does not
take place until after all the great sub-kingdoms of invertebrates
have been long in existence ; and there is no reason for think-
ing that future discoveries will materially affect the relative
order of succession thus indicated.

LITERATURE.

From the vast and daily-increasing mass of Silurian literature,
it is impossible to do more than select a small number of works
which have a classical and historical interest to the English-
speaking geologists, or which embody researches on special
groups of Silurian animals — anything like an enumeration of all
the works and papers on this subject being wholly out of the
question. Apart, therefore, from numerous and in many cases
extremely important memoirs, by various well-known observers,
both at home and abroad, the following are some of the more
weighty works to which the student may refer in investigating
the physical characters and succession of the Silurian strata and
their fossil contents : —

(1) 'Siluria. ' Sir Roderick Murchison.

(2) ' Geology of Russia and Europe. ' Murchison (with M.

de Verneuil and Count von Keyserling).

(3) ' Bassin Siluren de Boheme Centrale. ' Barrande.

(4) ' Introduction to the Catalogue of British Palaeozoic Fos-

sils in the Woodwardian Museum of Cambridge. '
Sedgwick.

(5) ' Die Urwelt Russlands. ' Eichwald.

(6) ' Report on the Geology of Londonderry, Tyrone, ' &c.

Portlock.

(/) "Geology of North Wales "--' Mem. Geol. Survey of
Great Britain, ' vol. iii. Ramsay.

(8) 'Geology of Canada.' 1863, Sir W. E. Logan; and the

' Reports of Progress of the Geological Survey ' since
1863.

(9) ' Memoirs of the Geological Survey of Great Britain. '
(10) Reports of the Geological Surveys of the State of New

York, Illinois, Ohio, Iowa, Michigan, Vermont, Wis-
consin, Minnesota, ' &c. By Emmons, Hall, Worthen,
Meek, Newberry, Orton, Winchell, Dale Owen, &c.
(n) * Thesaurus Siluricus. ' Bigsby.

134 HISTORICAL PALAEONTOLOGY.

(12) ' British Palaeozoic Fossils. ' M'Coy.

(13) 'Synopsis of the Silurian Fossils of Ireland.' M'Coy

(14) "Appendix to the Geology of North Wales "--'Mem

Geol. Survey,' vol. iii. Salter.

(15) 'Catalogue of the Cambrian and Silurian Fossils in the

Woodwardian Museum of Cambridge. ' Salter.

(16) 'Characteristic British Fossils.' Baily.

(17) 'Catalogue of British Fossils.' Morris.

(18) 'Palaeozoic Fossils of Canada.' Billings.

(19) 'Decades of the Geological Survey of Canada.' Billings,

Salter, Rupert Jones.

(20) ' Decades of the Geological Survey of Great Britain. '

Salter, Edward Forbes.

(21) 'Palaeontology of New York,' vols i.-iii. Hall.

(22) ' Palaeontology of Illinois. ' Meek and Worthen.

(23) 'Palaeontology of Ohio.' Meek, Hall, Whitfield, Nichol-

son.

(24) 'Silurian Fauna of West Tennessee' (Silurische Fauna

des Westlichen Tennessee). Ferdinand Roemer.

(25) ' Reports on the State Cabinet of New York. ' Hall.

(26) ' Lethaea Geognostica. ' Bronn.

(27) ' Index Palaeontologicus. ' Bronn.

(28) ' Lethaea Rossica. ' Eichwald.

(29) ' Lethaea Suecica. ' Hisinger.

(30) ' Palaeontologica Suecica. ' Angelin.

(31) ' Petref acta Germaniae. ' Goldfuss.

(32) ' Versteinerungen der Grauwacken-Formation in Sachsen. '

Geinitz.

(33) 'Organization of Trilobites ' (Ray Society). Burmeister.

(34) 'Monograph of the British Trilobites' (Palaeontograph-

ical Society). Salter.

(35) 'Monograph of the British Merostomata' (Palaeonto-

graphical Society). Henry Woodward.

(36) 'Monograph of British Brachiopoda' ( Palaeontolograph-

ical Society). Thomas Davidson.

(37) ' Graptolites of the Quebec Group. ' James Hall.

(38) ' Monograph of the British Graptolitidae. ' Nicholson.

(39) ' Monographs on the Trilobites, Pteropods, Cephalopods,

Graptolites, ' &c. Extracted from the ' Systeme Silurien
du Centre de la Boheme. ' Barrande.

(40) ' Polypiers Fossiles des Terrains Paleozoiques. ' and

'Monograph of the British Corals' ( Palaeontographical
Society). Milne Edwards and Jules Haime.

CHAPTER XL

THE DEVONIAN AND OLD RED SANDSTONE

PERIOD.

Between the summit of the Ludlow formation and the strata
which are universally admitted to belong to the Carboniferous
series is a great system of deposits, to which the name of " Old

DEVONIAN AND OLD RED PERIOD. 135

Red Sandstone" was originally applied, to distinguish them
from certain arenaceous strata which lie above the coal (" New
Red Sandstone"). The Old Red Sandstone, properly so-
called, was originally described and investigated as occurring
in Scotland and in South Wales and its borders; and similar
strata occur in the south of Ireland. Subsequently it was
discovered that Sediments of a different mineral nature, and
containing different organic remains, intervened between the
Silurian and the Carboniferous rocks on the continent of Eu-
rope, and strata with similar palseontological characters to these
were found occupying a considerable area in Devonshire. The
name of " Devonian " was applied to these deposits ; and this
title, by common usage, has come to be regarded as synony-
mous with the name of " Old Red Sandstone. " Lastly, a
magnificent series of deposits, containing marine fossils, and
undoubtedly equivalent to the true "Devonian" of Devon-
shire, Rhenish Prussia, Belgium, and France, is found to inter-
vene in North America between the summit of the Silurian
and the base of the Carboniferous rocks.

Much difficulty has been felt in correlating the true " Devon-
ian Rocks " with the typical " Old Red Sandstone "— this diffi-
culty arising from the fact that though both formations are
fossiliferous, the peculiar fossils of each have only been rarely
and partially found associated together. The characteristic
crustaceans and many of the characteristic fishes of the Old
Red are wanting in the Devonian ; whilst the corals and
marine shells of the latter do not occur in the former. It is
impossible here to enter into any discussion as to the merits
of the controversy to which this difficulty has given origin.
No one, however, can doubt the importance and reality of the
Devonian series as an independent system of rocks to be in-
tercalated in point of time between the Silurian and the Car-
boniferous. The want of agreement, both lithologically and
palaeontologically, between the Devonian and the Old Red,
can be explained by supposing that these two formations,
though wholly or in great part contemporaneous, and therefore
strict equivalents, represent deposits in two different geograph-
ical areas, laid down under different conditions. On this view,
the typical Devonian rocks of Europe, Britain, and North
America are the deep-sea deposits of the Devonian period, or,
at any rate, are genuine marine sediments formed far from
land. On the other hand, the "Old Red Sandstone" of'
Britain and the corresponding " Gaspe Group " of Eastern

136 HISTORICAL PALAEONTOLOGY.

Canada represent the shallow-water shore-deposits of the same
period. In fact, the former of these last-mentioned de-
posits contains no fossils which can be asserted positively
to be marine (unless the Eurypterids be considered so) ; and
it is even conceivable that it represents the sediments of an
inland sea. Accepting this explanation in the meanwhile,
we may very briefly consider the general succession of the
deposits of this period in Scotland, in Devonshire, and in
North America.

In Scotland the " Old Red " forms a great series of arena-
ceous and conglomeratic strata, attaining a thickness of many
thousands of feet, and divisible into three groups. Of these,
the Loiver Old Red Sandstone repose with perfect conform-
ity upon the highest beds of the Upper Silurian, the two for-
mations being almost inseparably united by an intermediate
series of " passage-beds. " In mineral nature this group con-
sists principally of massive conglomerates, sandstones, shales,
and concretionary limestones; and its fossils consist chiefly of
large crustaceans belonging to the family of the Eurypterids,
fishes, and plants. The Middle Old Red Sandstone consists of
flagstones, bituminous shales, and conglomerates, sometimes
with irregular calcareous bands; and its fossils are principally
fishes and plants. It may be wholly wanting, when the Upper
Old Red seems to repose unconformably upon the lower divi-
sion of the series. The Upper Old Red Sandstone consists of
conglomerates and grits, along with a great series of red and
yellow sandstones — the fossils, as before, being fishes and re-
mains of plants. The Upper Old Red graduates upwards
conformably into the Carboniferous series.

The Devonian rocks of Devonshire are likewise divisible
into a lower, middle, and upper division. The Lower
Devonian or Lynton Group consists of red and purple sand-
stones, with marine fossils, corresponding to the " Spirifer
Sandstein " of Germany, and to the arenaceous deposits (Scho-
harie and Cauda-Galli Grits) at the base of the American
Devonian. The Middle Devonian or Ilfracombe Group consists
of sandstones and flags, with calcareous slates and crystalline
limestones, containing many corals. It corresponds with the
great " Eif el Limestone " of the Continent, and, in a general
way, with the Corniferous Limestone and Hamilton Group of
North America. The Upper Devonian or Pilton Group, lastly,
consists of sandstones and calcareous shales which correspond
with the " Clymenia Limestone " and Cyprindina Shales " of

DEVONIAN AND OLD RED PERIOD. 137

the Continent, and with the Chemung and Portage groups of
North America. It seems quite possible, also, that the so-
called " Carboniferous Slates " of Ireland correspond with
this group, and that the former would be more properly re-
garded as forming the summit of the Devonian than the
base of the Carboniferous.

In no country m the world, probably, is there a finer
or more complete exposition of the strata intervening be-
tween the Silurian and Carboniferous deposits than in the
United States. The following are the main subdivisions
of the Devonian rocks in the State of New York, where
the series may be regarded as being typically developed
(% 67) :-

(1) Cauda-Galli Grit and Schoharie Grit. — Considering the
" Oriskany Sandstone " as the summit of the Upper Silurian,
the base of the Devonian is constituted by the arenaceous
deposits known by the above names, which rest quite conform-
ably upon the Silurian, and which represent the Lower
Devonian of Devonshire. The Cauda-Galli Grit is so-called
from the abundance of a peculiar spiral fossil (Spirophyton
cauda-Galli), which is of common occurrence in the Carbon-
iferous rocks of Britain, and is supposed to be the remains
of a sea-weed.

(2) The Corniferous or Upper Helderberg Limestone. — A
series of limestones usually charged with considerable quan-
tities of siliceous matter in the shape of hornstone or chert
(Lat. cornu, horn). The thickness of this group rarely exceeds
3000 feet ; but it is replete with fossils, more especially with
the remains of corals. The Corniferous Limestone is the
equivalent of the coral-bearing limestones of the Middle De-
vonian of Devonshire and the great " Eif el Limestone " of
Germany.

(3) The Hamilton Group — consisting of shales at the base
(" Marcellus shales ") ; flags, shales, and impure limestones
("Hamilton beds") in the middle; and again a series of shales
("Genesee Slates") at the top. The thickness of this group
varies from 200 to 1200 feet, and it is richly charged with
marine fossils.

(4) The Portage Group. — A great series of shales, flags and
shaly sandstones, with few fossils.

(5) The Chemung Group. — Another great series of sand-
stones and shales, but with many fossils. The Portage and
Chemung groups may be regarded as corresponding with the

138 HISTORICAL PALEONTOLOGY.

Upper Devonian of Devonshire. The Chemung beds are
succeeded by a great series of red sandstones and shales — the
" Catskill Group " — which pass conformably upwards into the
Carboniferous, and which may perhaps be regarded as the
equivalent of the great sandstones of the Upper Old Red in
Scotland.

Throughout the entire series of Devonian deposits in North
America no unconformability or physical break of any kind
has hitherto been detected; nor is there any marked interrup-
tion to the current of life, though each subdivision of the series
has its own fossils. No completely natural line can thus be
indicated, dividing the Devonian in this region from the Silu-
rian on the one hand, and the Carboniferous on the other
hand. At the same time, there is the most ample evidence,
both stratigraphical and palaeontological, as to the complete
independence of the American Devonian series as a distinct
life-system between the older Silurian and the later Carbon-
iferous. The subjoined section (fig. 76) shows diagrammatic-
ally the general succession of the Devonian rocks of North
America.

As regards the life of the Devonian period, we are now
acquainted with a large and abundant terrestrial flora — this
being the first time that we have met with a land vegetation
capable of reconstruction in any fulness. By the researches
of Cceppert, Unger, Dawson, Carruthers, and other botanists,
a knowledge has been acquired of a large number of Devonian
plants, only a few of which can be noticed here. As might
have been anticipated, the greater number of the vegetable
remains of this period have been obtained from such shallow-
water deposits as the Old Red Sandstone proper and the Gaspe
series of North America, and few traces of plant-life occur in
the strictly marine sediments. Apart from numerous remains,
mostly of a problematical nature, referred to the comprehensive
group of the Sea-weeds, a large number of Ferns have now
been recognized, some being of the ordinary plant-like type
(Pecopteris, Neuropteris', Alethopteris, Sphenopteris, &c.), whilst
others belong to the gigantic group • of the " Tree-ferns "
(Psaronius, Canlopteris, &c.) Besides these there is an abun-
dant development of the singular extinct types of the Lepido-
dendroids, the Sigillarioids, and the Calamites, all of which
attained their maximum in the Carboniferous. Of these, the
Lepidodendra may be regarded as gigantic, tree-like Club-mosses

DEVONIAN AND OLD RED PERIOD.

139

GENERALIZED SECTION OF THE DEVONIAN ROCKS OF
NORTH AMERICA.

Fig. 76.

Catskill Group.

Chemung Group.
Portage Group.

Hamilton Group.

Corniferous Limestone.

Schoharie Grit.
Cauda-Galli Grit.
Oriskany Sandstone.

Lower Helderberg.

; the Calamites are equally gigantic Horse-tails
(Equisetacea} ; and the Sigillarioids, equally huge in size, in
some respects hold a position intermediate between the Club-
mosses and the Pines (Conifers^. The Devonian rocks have
also yielded traces of many other plants (such as Annularia,
Asteropliyllites, Cardiocarpon, &c.), which acquire a greater pre-
dominance in the Carboniferous period, and which will be
spoken of in discussing the structure of the plants of the Coal-
measures. Upon the whole, the one plant which may be con-
sidered as specially characteristic of the Devonian (though not
confined to this series) is the Psilophyton (fig. 77) of Dr. Daw-
son. These singular plants have slender branching stems,
with sparse needle-shaped leaves, the young stems being at

140

HISTORICAL PALEONTOLOGY.

first coiled up, crosier-fashion, like the young fronds of ferns,
whilst the old branches carry numerous spore-cases. The
stems and branches seem to have attained a height of two or
three feet ; and they sprang from prostrate " root-stocks " or

creeping stems. Upon the whole,
Principal Dawson is disposed to
regard Psilophyton as a " general-
ized type" of plants intermediate
between the Ferns and the Club-
mosses. Lastly, the Devonian de-
posits have yielded the remains of
the first actual trees with which we-
are as yet acquainted. About the
nature of some of these (Ormoxy-
lon and Dadoxylon} no doubt can
be entertained, "since their trunks
not only show the concentric rings
of growth characteristic of exog-
enous trees in general, but their
woody tissue exhibits under the
microscope the " discs " which are
characteristic of the wood of the
Pines and Firs (see fig. 2). The
singular genus Prototaxites, how-
ever, which occurs in an older por-
tion of the Devonian series than
the above, is not in an absolutely
unchallenged position. By Prin-
cipal Dawson it is regarded as the
trunk of an ancient Conifer — the
most ancient known ; but Mr.
Carruthers regards it as more
probably the stem of a gigantic
sea-weed. The trunks of Proto-
taxites (fig. 78, A) vary from one
to three feet in diameter, and
exhibit concentric rings of growth ;
but its woody fibres have not
hitherto been clearly demonstrated
to possess discs. Before leaving

the Devonian vegetation, it may be mentioned that the hornstone
or chert so abundant in the Corniferous limestone of North
America has been shown to contain the remains of various

Fig. 11. — Restoration of Psilo-
phyton princeps Devonian, Can-
ada. (After Dawson.)

DEVONIAN AND OLD RED PERIOD.

141

microscopic plants (Diatoms and Desmids). We find also in
the same siliceous material the singular spherical bodies, with
radiating spines, which occur so abundantly in the chalk flints,
and which are termed Xanthidia. These may be regarded
as probably the spore-cases of the minute plants known as
Desmidice.

Fig. 78. — A, Trunk of Prototaxites Logam, eighteen inches in diameter, as seen in
the cliff near L'Anse Brehaut, Gasp6 ; B, Two wood-cells showing spiral fibres and
obscure pores, highly magnified. Lower Devonian, Canada. (After Dawson. )

The Devonian Protozoans have still to be fully investi-
gated. True Sponges (such as Astrceospongia, Sphcerospongia,
&c.) are not unknown; but by far the commonest repre-
sentatives of this sub-kingdom in the Devonian strata are
Stromatopora and its allies. These singular organisms (fig.
79) are not only very abundant in some of the Devonian lime-
stones— both in the Old World and the New — but they often
attain very large dimensions. However much they may differ
in minor details, the general structure of these bodies is that
of numerous, concentrically-arranged, thin, calcareous laminae,
separated by narrow interspaces, which in turn are crossed by
numerous delicate vertical pillars, giving the whole mass a
cellular structure, and dividing it into innumerable minute
quadrangular compartments. Many of the Devonian Stromato-

142

HISTORICAL PALEONTOLOGY.

pores also exhibit on their surface the rounded openings of
canals, which can hardly have served any other purpose than
that of permitting the sea-water to gain ready access to every
part of the organism.

No true Graptolites have ever been detected in strata of
Devonian age; and the whole of this group has become ex-
tinguished---unless we refer here the still surviving Dictyonema.
The Ccclenterates, however, are represented by a vast number
of Corals, of beautiful forms and very varied types. The
marbles of Devonshire, the Devonian limestones of the Eifel

Fig 79 . — a, Part of the under surface of Stromatopora tuberculata, showing the
wrinkled basement membrane and the openings of water-canals, of the natural size ;
6, Portion of the upper surf ace of the same, enlarged; c, Vertical section of a fragment,
magnified to show the internal structure. Corniferous Limestone, Canada. (Original.)

and of France, and the calcareous strata of the Corniferous
and Hamilton groups of America, are often replete with the
skeletons of these organisms — so much so as to sometimes
entitle the rock to be considered as representing an ancient
coral-reef. In some instances the Corals have preserved their
primitive calcareous composition; and if they are embedded
in soft shales, they may weather out of the rock in almost all
their original perfection. In other cases, as in the marbles of
Devonshire, the matrix is so compact and crystalline that the

DEVONIAN AND OLD RED PERIOD.

143

included corals can only be satisfactorily studied by means of
polished sections. In other cases, again, the corals have been
more or less completely converted into flint, as in the Cornifer-

Fig. 81 .— Zaphrentia cornicula, of the
natural size. Devonian, America. (Orig-
inal.)

Fig. 80. — Ci/stipfii/lluin vesiculosum,
showing a succession of cups produced by
budding from the original coral. Of the
natural size. Devonian, America and
Europe. (Original.)

F\g.82.—ffeliophyllum exiffuum, view-
ed from in front and behind. Of the nat-
ural size. Devonian.Canada. (Original.)

ous limestone of North America. When this is the case, they
often come, by the action of the weather, to stand out from
the enclosing rock in the boldest relief, exhibiting to the ob-

144 HISTORICAL PALEONTOLOGY.

server the most minute details of their organization. As before,
the principal representatives of the Corals are still referable to
the groups of the Rugosa and Tabulata. Amongst the Rugose
group we find a vast number of simple " cup-corals, " generally
known by the quarrymen as " horns, " from their shape. Of
the many forms of these, the species of Cyathophyllum, Helio-
phyllum (fig.82~),Zaphrentis (fig. 81), and Cystiphyllum (fig. 80),
are perhaps those most abundantly represented — none of these
genera, however, except Heliophyllum, being peculiar to the

Fig. 83.— Portion of a mass of Crepidophyllum Archiaci, of the natural size.
Hamilton Formation, Canada. (After Billings.)

Devonian period. There are also numerous compound Ru-
gose corals, such as species of Eridophyllum, Diphyphyl-
lum, Syringopora, Phillip sastrcea, and some of the forms of
Cyathophyllum and Crepidophyllum (fig. 83). Some of these
compound corals attain a very large size, and form of them-
selves regular beds, which have an analogy, at any rate, with
existing coral-reefs, though there are grounds for believing that
these ancient types differed from the modern reef-builders in
being inhabitants of deep water. The " Tabulate Corals " are
hardly less abundant in the Devonian rocks than the Rugosa;
and being invariably compound, they hardly yield to the latter
in the dimensions of the aggregations which they sometimes
form.

The commonest, and at the same time the largest, of these
are the " honeycomb corals, " forming the genus Favosites
(figs. 84, 85), which derive both their vernacular and their
technical names from their great likeness to masses of petrified

DEVONIAN AND OLD RED PERIOD.

145

honeycomb. The most abundant species are Favosites Goth-
landica and F. hemispherica, both here figured, which form
masses sometimes not less than two or three feet in diameter.
Whilst Favosites has acquired a popular name by its honey-
combed appearance, the resemblance of Michelinia to a fossil-
ized wasp's nest with the comb exposed is hardly less strik-
ing, and has earned for it a similar recognition from the

Fig. 84. — Portion of a mass of Favo-
titex Gottilandtca, of the natural size.
Upper Silurian and Devonian of Europe
and America. (Original.)

Fig. 85.— Fragment of Favosites fiemi-
tpherica, of the natural size. Upper Silu-
rian and Devonian of America. (After
Billings.)

non-scientific public. In addition to these, there are numer-
ous branching or plant-like Tabulate Corals, often of the most
graceful form, which are distinctive of the Devonian in all
parts of the world.

The Echinodcnns of the Devonian period call for little
special notice. Many of the Devonian limestones are " crin-
oidal;" and the Crinoids are the most abundant and widely-
distributed representatives of their class in the deposits of
this period.

The Cystideans, with doubfful exceptions, have not been
recognized in the Devonian; and their place is taken by the
allied group of the " Pentremites, " which will be further spoken
of as occurring in the Carboniferous rocks. On the other hand,
the Star-fishes, Brittle-fishes, and Sea-urchins are all continued
by types more or less closely allied to those of the preceding
Upper Silurian.

Of the remains of Ringed-worms (Annelidcs), the most
numerous and the most interesting are the calcareous envelopes
of some small tube-inhabiting species. No one who has visited
the seaside can have failed to notice the little spiral tubes of
the existing Spirorbis growing attached to shells, or covering

146

HISTORICAL PALEONTOLOGY.

Fig. 86.— a, Spirorbia omphalode» natural size
and enlarged, Devonian, Europe and America ;
b, Spirorbis Arkonensit, of the natural size and
enlarged ; c, The same, with the tube twisted in
the reverse direction. Devonian, America. (Orig-
inal.)

the fronds of the commoner Sea- weeds (especially Fucus ser-
ratus}. These tubes are inhabited by a small Annelide, and
structures of a similar character occur not uncommonly from
the Upper Silurian upwards. In the Devonian rocks, Spir-
orbis is an extremely common fossil, growing in hundreds
attached to the outer surface of corals and shells, and appearing
in many specific forms (figs. 86 and 87) ; but almost all the
known examples are of small size, and are liable to escape a

cursory examination.

The Crustaceans of
the Devonian are prin-
cipally Eurypterids and
Trilobites. Some of the
former attain gigantic
dimensions, and the
quarrymen in the Scotch
Old Red give them the
name of " seraphim, "
from their singular
scale - like ornamenta-
tion. The Trilobites,
though still sufficiently
abundant in some local-
ities, have undergone a
yet further diminution

Fig. 87.— a 6, Spirorbis laxus, enlarged, Upper since tne close of the

Silurian, America ; c, Spirorbis spinulifera, of the Tinner Silurian Tn both

natural size and enlarged, Devonian, Canada. (Af- ~PP ^ ?' 1

ter Hall and the Author. ) America and Europe

quite a number of gen-

sric types have survived from the Silurian, but few or no new
ones make their appearance during this period in either the Old
World or the New. The species, however, are distinct; and the
principal forms belong to the genera Phacops (fig. 88, a, c, d),
Homalonotus (fig. 88, 6), Proetus, and Bronteus. The species
figured opposite under the name of Phacops latifrons (fig. 88, a),
has an almost world-wide distribution, being found in the
Devonian of Britain, Belgium, France, Germany, Russia, Spain,
and South America; whilst its place is taken in North Amer-
ica by the closely-allied Phacops rana. In addition to the
Trilobites, the Devonian deposits have yielded the remains of
a number of the minute Ostracoda, such as Entomis (" Cypri-
dina"), Leperditia, &c., which sometimes occur in vast num-
bers, as in the so-called " Cypridina Slates" of the German

DEVONIAN AND OLD RED PERIOD.

147

Devonian. There are also a few forms of Phyllopods (Es-
therid). Taken as a whole, the Crustacean fauna of the
Devonian period presents many alliances with that of the

Fig. 88 — Devonian Trilobites. a, Pfiacops lalifrona, Devonian of Britain, the Con-
tinent of Europe, and South America ; 6, Homalonotua armatits, Europe ; c, Phacop*
(Trimerocepkalus) Icevis, Europe; d, Head-shield of Phacopt (Portlockia) granulatus,
Europe. (After Salter and Bucmeister.)

Upper Silurian, but has only slight relationships with that of
the Lower Carboniferous.

Besides Crustaceans, we meet here for the first time with
the remains of air-breathing Articulates, in the shape of Insects.
So far, these have only been obtained from the Devonian
rocks of North America, and they indicate the existence of 'at
least four generic types, all more or less allied to the existing
May-flies (Ephemerida). One of these interesting primitive
insects, namely, Platephemera antiqua (fig. 89), appears to have
measured five inches in ex-
panse of wing; and another
(Xenoneura antiquorum}
has attached to its wing the
remains of a " stridulating-
organ " similar to that pos-
sessed by the modern Grass-
hoppers— the instrument, as
Principal Dawson remarks,
of " the first music of living rig. 89.— wing of piatephemera anti-
things that Geology as yet ££, Devonlan' America« (After Daw'
reveals to us. "

Amongst the Mollusca, the Devonian rocks have yielded a

148

HISTORICAL PALAEONTOLOGY.

great number of the remains of Sea-mosses (Polysoa). Some
of these belong to the ancient type Ptilodictya, which seems tc

Fig. 91. — Fragment of
Ceriopora Hamiltonensls,
of the natural size and
Fig. 90. — Fragment of Clathopora intertexta, of the enlarged. Devonian, Cana-
natural size and enlarged. Devonian, Canada. (Original.) da. (Original.)

disappear here, or to the allied Clathropora (fig. 90), with its
fenestrated and reticulated fronds. We meet also with the
graceful and delicate stems of Ceriopora (fig. 91).

Fig. 92. — Fragment of Fenestella magnified,
of the natural size and enlarged. Devonian,
Canada. (Original.)

Fig. 93. — Fragment of Retepora
Phillipai, of, the natural size and
enlarged. Devonian, Canada. (Orig-
inal.)

Fig. 94.— Fragment of Fenettella
cribrosa, of the natural size and en-
larged. Devonian,Canada. (Original.)

The majority of the Devonian Polyzoa belong, however, to
the great and important Palaeozoic group of the Lace-corals
(Fenestella, figs. 92 and 94, Retepora, fig. 93, Polypora, and

DEVONIAN AND OLD RED PERIOD. 149

their allies). In all these forms there is a horny skeleton, of a
fan-like or funnel-shaped form, which grew attached by its
base to some foreign body. The frond consists of slightly-
diverging or nearly parallel branches, which are either united
by delicate cross-bars, or which bend alternately from side to
side, and become directly united with one another at short
intervals — in either case giving origin to numerous oval or
oblong perforations, which communicate to the whole plant-
like colony a characteristic netted and lace-like appearance.
On one of its surfaces — sometimes the internal, sometimes the
external — the frond carries a number of minute chambers or
" cells, " which are generally borne in rows on the branches,
and of which each originally contained a minute animal.

Fig. 95. — Spirifera

sculptilis. Devonian, Ca- Fig. 96.— Spirifera mucronata. Devonian, America,

nada. (After Billings.) (After Billings.)

The Brachiopods still continue to be represented in great
force through all the Devonian deposits, though not occurring
in the true Old Red Sandstone. Besides such old types as
Orthis, Strophomena, Lingula, Athyris, and Rhynchonella, we
find some entirely new ones ; whilst various types which only
commenced their existence in the Upper Silurian, now under-
go a great expansion and development. This last is especially
the case with the two families of the Spiriferidce and the Pro-
ductida. The Spirifers, in particular, are especially character-
istic of the Devonian, both in the Old and New Worlds — some
of th6 most typical forms, such as Spirifera mucronata (fig. 96),
having the shell " winged, " or with the lateral angles prolonged
to such an extent as to have earned for them the popular name
of " fossil-butterflies. " The closely-allied Spirifera disjuncta
occurs in Britain, France, Spain, Belgium, Germany, Russia,
and China. The family of the Productida commenced to exist
in the Upper Silurian, in the genus Chonetes; and we shall
hereafter find it culminating in the Carboniferous in many

ISO HISTORICAL PALAEONTOLOGY.

forms of the great genus Producta * itself. In the Devonian
period, there is an intermediate state of things, the genus
Chonetes being continued in new and varied types, and the
Carboniferous Producta being represented by many forms of
the allied group Productella. Amongst other well-known De-
vonian Brachiopods may be mentioned the two Iong7lived and
persistent types Atrypa reticularis (fig. 97) and Strophomena
rhomboidalis (fig. 98). The former of these commences in the
Upper Silurian, but is more abundantly developed in the De-
vonian, having a geographical range that is nothing less than

Fig. 97 —Atrypa reticularis. Upper Silurian and Devonian of Europe
and America. (After Billings.)

world-wide; whilst the latter commences in the Lower Silurian,
and, with an almost equally cosmopolitan range, survives into
the Carboniferous period.

The Bivalves (Lamellibranchiata} of the Devonian call for

Fig. 98. — Strophomena rhomboidalia. Lower Silurian, Upper Silurian, and
Devonian of Europe and America.

no special comment, the genera Pterinea and Megalodon being,
perhaps, the most noticeable. The Univalves (Gasteropods),
also, need not be discussed in detail, though many interesting

* The name of this genus is often written Productus, just as Spirifera
is often given in the masculine gender as Spirifer (the name originally
given to it). The masculine termination to these names is, however, gram-
matically incorrect, as the feminine noun cochlea (shell) is in these cases
understood.

DEVONIAN AND OLD RED PERIOD.

151

Fig. 99.— Different views of Platyceraa du-
mosum, of the natural size. Devonian, Can-
ada. (Original.)

forms of this group are known. The type most abundantly
represented, especially in America, is Platyceras (fig. 99),

comprising thin, wide-
mouthed shells, probably
most nearly allied to the
existing " Bonnet-limpets, "
and sometimes attaining
very considerable dimen-
sions. We may also note
the continuance of the
genus Euomphalus, with
its discoidal spiral shell.
Amongst the Heteropods,
the survival of Bellerophon
is to be recorded ; and in the " Winged-snails, " or Pteropods, we
find new forms of the old genera Tentaculites and Conularia
(fig. 100). The latter, with its fragile, conical, and often beauti-
fully ornamented shell, is especially noticeable.

The remains of Cephalopoda are far from uncommon in the
Devonian deposits, all the known forms
being still Tetrabranchiate. Besides the
ancient types Orthoceras and Cyrtoceras,
we have now a predominance of the
spirally-coiled chambered shells of Goni-
atites and Clymenia. In the former of
these the shell is shaped like that of the
Nautilus; but the partitions between tbe
chambers ("septa") a're more or less
lobed, folded, or angulated, and the
" siphuncle " runs along the back or con-
vex side of the shell — these being char-
acters which approximate Goniatites to
the true Ammonites of the later rocks.
In Clymenia, on the other hand, whilst

,, u 11 /c \ • -i j • o -Fig. 100. — Conularia or-

the shell (ng. 101) is coiled into a flat nata, of the natural [size.

spiral, and the partitions or septa are De™1^. Europe,
simple or only slightly lobed, there is still

this difference, as compared with the Nautilus, that the tube of
the siphuncle is placed on the inner or concave side of the
shell. The species of Clymenia are exclusively Devonian in
their range; and some of the limestones of this period in
Germany are so richly charged with fossils of this genus as to
have received the name of " Clymenien-kalk. "

152

HISTORICAL PALEONTOLOGY.

The sub-kingdom of the Vertebrates is still represented by
Fishes only ; but these are so abundant, and belong to such
varied types, that the Devonian period has been appropriately
called the " Age of Fishes. " Amongst the existing fishes there
are three great groups which are of special geological impor-
tance, as being more or less extensively represented in past time.
These groups are: (i) The Bony Fishes (Teleostei}, comprising
most existing fishes, in which the skeleton is more or less com-
pletely converted into bone; the tail is symmetrically lobed or
divided into equal moieties; and the scales are usually thin,
horny, flexible plates, which overlap one another to a greater

Fig. 101. — Clymenia SedgwickU . Devonian, Europe.

or less extent. (2) The Ganoid Fishes (Ganoidei), comprising
the modern Gar-pikes, Sturgeons, &c., in which the skeleton
usually more or less completely retains its primitive soft and
cartilaginous condition ; the tail is generally markedly unsym-
metrical, being divided into two unequal lobes ; and the scales
(when present) have the form of plates of bone, usually cov-
ered by a layer of shining enamel. These scales may overlap;
or they may be rhomboidal plates, placed edge to edge in
oblique rows; or they have the form of large-sized bony plates,
which are commonly united in the region of the head to form
a regular buckler. (3) The Placoid Fishes, or Elasmobranchii,

DEVONIAN AND OLD RED PERIOD. 153

comprising the Sharks, Rays, and Chimcerce of the present day,
in which the skeleton is cartilaginous ; the tail is unsymmetric-
ally lobed; and the scales have the form of detached bony
plates of variable size, scattered in the integument.

It is to the two last of these groups that the Devonian fishes
belong, and they are more specially referable to the Ganoids.
The order of the Ganoid fishes at the present day comprises
by some seven or eight genera, the species of which princi-
pally or exclusively inhabit fresh waters, and all of which are
confined to the northern hemisphere. As compared, there-
fore, with the Bony fishes, which constitute the great majority
of existing forms, the Ganoids form but an extremely small and
limited group. It was far otherwise, however, in Devonian
times. At this period, the bony fishes are not known to have
come into existence at all, and the Ganoids held almost undis-
puted possession of the waters. To what extent the Devonian
Ganoids were confined to fresh waters remains yet to be proved ;
and that many of them lived in the sea fs certain. It was
formerly supposed that the Old Red Sandstone of Scotland
and Ireland, with its abundant fish-remains, might perhaps be
a fresh-water deposit, since the habitat of its fishes is uncer-
tain, and it contains no indubitable marine fossils. It has
been now shown, however, that the marine Devonian strata of
Devonshire and the continent of Europe contain some of the
most characteristic of the Old Red Sandstone fishes of Scot-
land; whilst the undoubted marine deposit of the Corniferous
limestone of North America contains numerous shark-like and
Ganoid fishes, including such a characteristic Old Red genus
as Coccosteus. There can be little doubt, therefore, but that the
majority of the Devonian fishes were truly marine in their habits,
though it is probable that many of them lived in shallow water,
in the immediate neighborhood of the shore, or in estuaries.

The Devonian Ganoids belong to a number of groups; and
it is only possible to notice a few of the most important forms
here. The modern group of the Sturgeons is represented,
more or less remotely, by a few Devonian fishes — such as As-
terosteus; and the great Macro petalichthys of the Corniferous
limestone of North America is believed by Newberry to belong
to this group. In this fish (fig. 102, fr) the skull was of large
size, its outer surface being covered with a tuberculated enamel ;
and, as in the existing Sturgeons, the mouth seems to
have been wholly destitute of teeth. Somewhat allied, also, to
the Sturgeons, is a singular group of armored fishes, which is

154

HISTORICAL PALEONTOLOGY.

highly characteristic of the Devonian of Britain and Europe,
and less so of that of America. In these curious forms the
head and front extremity of the body were protected by a
buckler composed of large enameled plates, more or less
firmly united to one another; whilst the hinder end of the body
was naked, or was protected with small scales. Some forms of

Fig. 102.— Fishes of the Devonian rocks of America, a, Diagram of the jaws and
teeth of Dinichthys Hertzeri, viewed from the front, and greatly reduced ; 6, Diagram
of the skull of Macropetalichthys Sullivanti, reduced In size ; c, A portion of the en-
amelled surface of the skull of the same, magnified ; d, One of the scales of Onychodus
sigmoides, of the natural size ; e, One of the front teeth of the lower jaw of the same,
of the natural size ; /, Fin-spine of MachoRracanthus major, a shark-like fish reduced
In size. (After Newberry.;

this group — such as Pteraspis and Coccosteus — date from the
Upper Silurian; but they attain their maximum in the Devo-
nian, and none of them are known to pass upwards into the
overlying Carboniferous rocks. Amongst the most character-
istic forms of this group may be mentioned Cephalaspis (fig.
103) and Pterichthys (fig. 104). In the former of these the

DEVONIAN AND OLD RED PERIOD. 155

head-shield is of a crescentic shape, having its hinder angles
produced backwards into long " horns, " giving it the shape of
a " saddler's knife. " No teeth have been discovered ; but the
body was covered with small ganoid scales, and there was an
unsymmetrical tail-fin. In Pterichthys — which, like the preced-
ing, was first brought to light by the labors of Hugh Miller —
the whole of the head and the front part of the body were de-
fended by a buckler of firmly-united enamelled plates, whilst
the rest of the body was covered with small scales. The form
of the "pectoral fins" was quite unique — these having the
shape of two long, curved spines, somewhat like wings, covered
by finely-tuberculated ganoid plates. All the preceding forms
of this group are of small size; but few fishes, living or extinct,
could rival the proportions of the great Dinichthys, referred to

Fig. 103.— Cephalaspia Lyellii. Old Red Sandstone, Scotland. (After Page.)

this family by Newberry. In this huge fish (fig. 102, a) the
head alone is over three feet in length, and the body is sup-
posed to have been twenty-five or thirty feet long. The head
was protected by a massive cuirass of bony plates firmly articu-
lated together, but the hinder end of the body seems to have
been simply enveloped in a leathery skin. The teeth are of
the most formidable description, consisting in both jaws of
serrated dental plates behind, and in front of enormous coni-
cal tusks (fig. 102, a). Though immensely larger, the teeth of
Dinichthys present a curious resemblance to those of the exist-
ing Mud-fishes (Lepidosiren}.

In another great group of Devonian Ganoids, we meet with
fishes more or less closely allied to the living Polypteri (fig.
105) of the Nile and Senegal. In this group (fig. 106) the
pectoral fins consist of a central scaly lobe carrying the fin-

156 HISTORICAL PALAEONTOLOGY.

rays on both sides, the scales being sometimes rounded and
overlapping (fig. 106), or more commonly rhomboidal and
placed edge to edge (fig. 105, A). Numerous forms of these

Fig. IQl.—Pterichthys cornutua. Old Bed Sandstone, Scotland.

(After Agassi z.)

" Fringe-finned " Ganoids occur in the Devonian strata, such
as Holoptychius, Glyptolamus, Osteolepis, Phaneropleuron, &c.
To this group is also to be ascribed the huge Onychodus (fig.
102, d and e), with its large, rounded, overlapping scales, an
inch in diameter, and its powerful pointed teeth. It is to be
remembered, however, that some of these " Fringe-finned "
Ganoids are probably referable to the small but singular group
of the "Mud-fishes" (Dipnoi}, represented at the present day
by the singular Lepidosiren of South America and Africa, and
the Ceratodus of the rivers of Queensland.

Leaving the Ganoid fishes, it still remains to be noticed that
the Devonian deposits have yielded the remains of a number
of fishes more or less closely allied to the existing Sharks,
Rays, and Chimccrce (the Elasmobranchii). The majority of
the forms here alluded to are allied not to the true Sharks and
Dog-fishes, but to the more peaceable u Port Jackson Sharks, "
with their blunt teeth, adapted for crushing the shells of Mol-
luscs. The collective name of " Cestracionts " is applied to
these; and we have evidence of their past existence in the
Devonian seas both by their teeth, and by the defensive spines
which were implanted in front of a greater or less number of
the fins. These are bony spines, often variously grooved,
serrated, or ornamented, with hollow bases, implanted in the
integument, and capable of being erected or depressed at will.
Many of these " fin-spines " have been preserved to us in the
fossil condition, and the Devonian rocks have yielded examples
belonging to many genera. As some of the true Sharks and

DEVONIAN AND OLD RED PERIOD.

157

Dog-fishes, some of the Ganoids, and even some Bony fishes,
possess similar defences, it is often a matter of some uncer-
tainty to what group a given spine is to be referred. One of
these spines, belonging to the genus Machcer acanthus, from the
Devonian rocks of America, has been figured in a previous
illustration (fig. 102, /).

In conclusion, a very few words may be said as to the
validity of the Devonian series as an independent system of
rocks, preserving in its successive strata the record of an
independent system of life. Some high authorities have been
inclined to the view that the Devonian formation has in nature
no actual existence, but that it is made up partly of beds
which should be referred to the summit of the Upper Silurian,

B

Fig. 105.— A, Polypterus, a recent Ganoid fish ; B. Osteolepis, a Devonian Ganoid
a, a, Pectoral fins, showing the fin-rays arranged round a central lobe.

and partly of beds which properly belong to the base of the
Carboniferous. This view seems to have been arrived at in
consequence of a too exclusive study of the Devonian series
of the British Isles, where the physical succession is not wholly
clear, and where there is a striking discrepancy between the
organic remains of those two members of the series which are
known as the " Old Red Sandstone " and the " Devonian "
rocks proper. This discrepancy, however, is not complete;
and, as we have seen, can be readily explained on the sup-
position that the one group of rocks presents us with the

158 HISTORICAL PALEONTOLOGY.

shallow water and littoral deposits of the period, while in the
other we are introduced to the deep-sea accumulations of the
same period. Nor can the problem at issue be solved by an
appeal to the phenomena of the British area alone, be the
testimony of these what it may. As a matter of fact, there is
at present no sufficient ground for believing that there is any
irreconcilable discordance between the succession of rocks
and of life in Britain during the period which elapsed between
the deposition of the Upper Ludlow and the formation of the

Fig. lOG.—Holoptycfiius nobiliasimn*, restored. Old Red Sandstone, Scotland.
A, Scale of the same.

Carboniferous Limestone, and the order of the same phe-
nomena during the same period in other regions. Sohie of
the Devonian types of life, as is the case with all great forma-
tions, have descended unchanged from older types ; others
pass upwards unchanged to the succeeding period: but the
fauna and flora of the Devonian period are, as a whole, quite
distinct from those of the preceding Silurian or the succeeding
Carboniferous; and they correspond to an equally distinct
rock-system, which in point of time holds an intermediate
position between the two great groups just mentioned. As
before remarked, this conclusion may be regarded as suffi-
ciently proved even by the phenomena of a British area ;
but it may be said to be rendered a certainty by the study of
the Devonian deposits of the continent of Europe — or, still
more, by the investigation of the vast, for the most part un-
interrupted and continuous series of sediments which com-
menced to be laid down in North America at the beginning of
the Upper Silurian, and did not cease till, at any rate, the close
of the Carboniferous.

DEVONIAN AND OLD RED PERIOD. 159

LITERATURE.

The following list comprises the more important works and
memoirs to which the student of Devonian rocks and fossils
may refer: —

(1) ' Siluria. ' Sir Roderick Murchison.

(2) ' Geology of Russia in Europe. ' Murchison (together

with De Verneuil and Count von Keyserling).

(3) " Classification of the Older Rocks of Devon and Corn-
wall " — ' Proc. Geol. Soc., ' vol. iii., 1839. Sedgwick and
Murchison.

(4) " On the Physical Structure of Devonshire ; " and on the

" Classification of the Older Stratified Rocks of Devon-
shire and Cornwall"— ' Trans. Geol. Soc.,' vol. v., 1840.
Sedgwick and Murchison.

(5) "On the Distribution and Classification of the Older or

Palaeozoic Rocks of North Germany and Belgium " —
'Geol. Trans.,' 2d ser., vol. vi., 1842. Sedgwick and
Murchison.

(6) 'Report on the Geology of Cornwall, Devon, and West

Somerset.' De la Beche.

(7) ' Memoirs of the Geological Survey of Ireland and Scot-

land.' Jukes and Geikie.

(8) " On the Carboniferous Slate (or Devonian Rocks) and

the Old Red Sandstone of South Ireland and North
Devon " — ' Quart. Journ. Geol. Soc., ' vol. xxii. Jukes.

(9) " On the Physical Structure of West Somerset and North

Devon ; " and on the " Palaeontological Value of De-
vonian Fossils " — ' Quart. Journ. Geol. Soc., ' vol. iii.
Etheridge.

(10) " On the connection of the Lower, Middle, and Upper

Old Red Sandstone of Scotland "—' Trans. Edin. Geol.
Soc.,' vol. i. part ii. Powrie.

(11) ' The Old Red Sandstone, ' ' The Testimony of the Rocks, '

and ' Footprints of the Creator. ' Hugh Miller.

(12) "Report on the 4th Geological District" — 'Geology of

New York. ' vol. iv. James Hall.

(13) 'Geology of Canada,' 1863. Sir W. E. Logan.

Acadian Geology.' Dawson.
Manual of Geology. ' Dana.

(1

Geological Survey of Ohio, ' vol. i.

Geological Survey of Illinois, ' vol i.

(18) ' Palaeozoic Fossils of Cornwall, Devon, and West Somer-

set. ' Phillips.

(19) ' Recherches sur les Poissons Fossiles. ' Agassiz.

(20) ' Poissons de 1'Old Red. ' Agassiz.

(21) "On the Classification of Devonian Fishes" — 'Mem.

Geol. Survey of Great Britain. ' Decade X. Huxley.

(22) ' Monograph of the Fishes of the Old Red Sandstone of

Britain' (Palaeontographical Society). Powrie and Lan-
kester.

(23) ' Fishes of the Devonian System, Palaeontology of Ohio. '

Newberry.

160 HISTORICAL PALEONTOLOGY.

(24) 'Monograph of British Trilobites' ( Palaeontographical

Society). Salter.

(25) 'Monograph of British Merostomata ' ( Palaeontograph-

ical Society). Henry Woodward.

(26) 'Monograph of British Brachiopoda' ( Palaeontograph-

ical Society). .Davidson.

(27) '^Monograph of British Fossil Corals' Palaeontograph-

ical Society). Milne-Edwards and Haime.

(28) 'Polypiers Foss. des Terrains Paleozoiques. ' Milne-

Edwards and Jules Haime.

(29) "Devonian Fossils of Canada West "— ' Canadian Jour-
nal, ' new sen, vols. iv.-vi Billings.

(30) ' Palaeontology of New York, ' vol. iv. James Hall.

(31) 'Thirteenth, Fifteenth, and Twenty-third Annual Reports

on the State Cabinet. ' James Hall.

(32) ' Palaeozoic Fossils of Canada, ' vol. ii. Billings.

(33) 'Reports on the Palaeontology of the Province of Ontario

for 1874 and 1875. ' Nicholson.

(34) "The Fossil Plants of the Devonian and Upper Silurian

Formations of Canada "— ' Geol. Survey of Canada. '
Dawson.

(35) ' Petrefacta Germaniae. ' Goldfuss.

(36) ' Versteinerungen der Grauwacken-formation. ' &c. Geinitz.

(37) ' Beitrag zur Palaeontologie des Thuringer-Waldes. '
Richter and Unger.

(38) ' Ueber die Placodermen des Devonischen Systems. '

Pander.

(39) ' Die Gattungen der Fossilen Pflanzen. ' Goeppert.

(40) ' Genera et Species Plantarum Fossilium. ' Unger.

CHAPTER XII.

THE CARBONIFEROUS PERIOD.

Overlying the Devonian formation is the great and impor-
tant series of the Carboniferous Rocks, so called because workable
beds of coal are more commonly and more largely developed
in this formation than in any other. Workable coal-seams,
however, occur in various other formations (Jurassic, Cretace-
ous, Tertiary), so that coal is not an exclusively Carboniferous
product; whilst even in the Coal-measures themselves the coal
bears but a very small proportion to the total thickness of
strata, occurring only in comparatively thin beds intercalated
in a great series of sandstones, shales, and other genuine
aqueous sediments.

THE CARBONIFEROUS PERIOD. 161

Stratigraphically, the Carboniferous rocks usually repose
conformably upon the highest Devonian beds, so that the line
of demarcation between the Carboniferous and Devonian for-
mations is principally a palaeontological one, founded on the
observed differences in the fossils of the two groups. On the
other hand, the close of the Carboniferous period seems to
have been generally, though not universally, signalized by
movements of the crust of the earth, so that the- succeeding
Permian beds often lie unconformably upon the Carboniferous
sediments.

Strata of Carboniferous age have been discovered in almost
every large land-area which has been sufficiently investigated;
but they are especially largely developed in Britain, in various
parts of the continent of Europe, and in North America.
Their general composition, however, is, comparatively speak-
ing, so uniform, that it will suffice to take a comprehensive
view of the formation without considering any one area in
detail, though in each region the subdivisions of the formation
are known by distinctive local names. Taking such a com-
prehensive view, it is found that the Carboniferous series is
generally divisible into a Loiver and essentially calcareous
group (the " Sub-Carboniferous " or " Carboniferous Lime-
stone"); a Middle and principally arenaceous group (the
" Millstone Grit ") ; and an Upper group, of alternating shales
and sandstones, with workable seams of coal (the " Coal-
measures ").

I. The Carboniferous. Sub-Carboniferous, or Mountain Lime-
stone Series constitutes the general base of the Carboniferous
system. As typically developed in Britain, the Carboniferous
Limestone is essentially a calcareous formation, sometimes
consisting of a mass of nearly pure limestone from 1000 to
2000 feet in thickness, or at other times of successive great
beds of limestone with subordinate sandstones and shales.
In the north of England the base of the series consists of
pebbly conglomerates and coarse sandstones; and in Scot-
land generally, the group is composed of massive sandstones
with a comparatively feeble development of the calcareous
element. In Ireland, again, the base of the Carboniferous
Limestone is usually considered to be formed by a locally-
developed group of grits and shales (the " Coomhola Grits "
and "Carboniferous Slate"), which attain the thickness of
about 5000 feet, and contain an intermixture of Devonian
with Carboniferous types of fossils. Seeing that the Devonian

162 HISTORICAL PALEONTOLOGY.

formation is generally conformable to the Carboniferous, we
need feel no surprise at this intermixture of forms; nor does it
appear to be of great moment whether these strata be referred
to the former or to the latter series. Perhaps the most satis-
factory course is to regard the Coomhola Grits and Carbon-
iferous Slates as "passage-beds" between the Devonian and
Carboniferous; but any view that may be taken as to the
position of these beds, really leaves unaffected the integrity
of the Devonian series as a distinct life-system, which, on the
whole, is more closely allied to the Silurian than to the Car-
boniferous. In North America, lastly, the Sub-Carboniferous
series is never purely calcareous, though in the interior of the
continent it becomes mainly so. In other regions, however,
it consists principally of shales and sandstones, with subor-
dinate beds of limestone, and sometimes with thin beds of
coal or deposits of clay-ironstone.

II. The Millstone Grit.— The highest beds of the Carbon-
iferous Limestone series are succeeded, generally with perfect
conformity, by a series of arenaceous beds, usually known as
the Millstone Grit. As typically developed in Britain, this
group consists of hard quartzose sandstones, often so large-
grained and coarse in texture as to properly constitute fine
conglomerates. In other cases there are regular conglomer-
ates, sometimes with shales, limestones, and thin beds of coal —
the thickness of the whole series, when well developed, varying
from 1000 to 5000 feet. In North America, the Millstone
Grit rarely reaches 1000 feet in thickness; and, like its Brit-
ish equivalent, consists of coarse sandstones and grits, some-
times with regular conglomerates. Whilst the Carboniferous
Limestone was undoubtedly deposited in a tranquil ocean
of considerable depth, the coarse mechanical sediments of the
Millstone Grit indicate the progressive shallowing of
the Carboniferous seas, and the consequent supervention
of shore-conditions.

III. The Coal-measures. — The Coal-measures properly so
called rest conformably upon the Millstone Grit, and usually
consist of a vast series of sandstones, shales, grits, and coals,
sometimes with beds of limestone, attaining in some regions a
total thickness of from 7000 to nearly 14,000 feet. Beds of
workable coal are by no means unknown in some areas in the
inferior group of the Sub-Carboniferous; but the general state-
ment is true, that coal is mostly obtained from the true Coal-
measures — the largest known, and at present most produc-

THE CARBONIFEROUS PERIOD. 163

tive coal-fields of the world being in Great Britain, North
America, and Belgium. Wherever they are found, with
limited exceptions, the Coal-measures present a singular
general uniformity of mineral composition. They consist,
namely, of an indefinite alternation of beds of sandstone,
shale, and coal, sometimes with bands of clay-ironstone or beds
of limestone, repeated in no constant order, but sometimes
attaining the enormous aggregate thickness of 14,000 feet, or
little short of 3 miles. The beds of coal differ in number and
thickness in different areas, but they seldom or never exceed
one-fiftieth part of the total bulk of the formation in thickness.
The characters of the coal itself, and the way in which the
coal-beds were deposited, will be briefly alluded to in speaking
of the vegetable life of the period. In Britain, and in the Old
World generally, the Coal-measures are composed partly of
genuine terrestrial deposits — such as the Coal — and partly of
sediments accumulated in the fresh or brackish waters of vast
lagoons, estuaries, and marshes. The fossils of the Coal-
measures in these regions are therefore necessarily the remains
either of terrestrial plants and animals, or of such forms of
life as inhabit fresh or brackish waters, the occurrence of strata
with marine fossils being quite a local and occasional phe-
nomenon. In various parts of North America, on the other
hand, the Coal-measures, in addition to sandstones, shales,
coal-seams, and bands of clay-ironstone, commonly include
beds of limestone, charged with marine remains, and indicating
marine conditions. The subjoined section (fig. 107) gives, in
a generalized form, the succession of the Carboniferous strata
in such a British area as the north of England, where the series
is developed in a typical form.

As regards the life of the Carboniferous period, we naturally
find, as has been previously noticed, great differences in dif-
ferent parts of the entire series, corresponding to the different
mode of origin of the beds. Speaking generally, the Lower
Carboniferous (or the Sub-Carboniferous) is characterized by
the remains of marine animals; whilst the Upper Carbon-
iferous (or Coal-measures) is characterized by the remains
of plants and terrestrial animals. In all those cases, how-
ever, in which marine beds are found in the series of the
Coal-measures, as is common in America, then we find that the
fossils agree in their general characters with those of the older
marine deposits of the period.

Owing to the fact that coal is simply compressed and other-

1 64

HISTORICAL PALEONTOLOGY.

wise altered vegetable matter, and that it is of the highest
economic value to man, the Coal-measures have been more
thoroughly explored than any other group of strata of equiva-

GENERALIZED SECTION OF THE CARBONIFEROUS STRATA
OF THE NORTH OF ENGLAND.

Fig. 107.

Permian (New Red
Sandstone).

> Coal-measures.

Millstone Grit.

Yoredale Series.

Scar-Limestone Series

Basement Beds (Con
glomerates and
Sandstones).

lent thickness in the entire geological series. Hence we have
already a very extensive acquaintance with the plants of the

THE CARBONIFEROUS PERIOD. 165

Carboniferous period; and our knowledge on this subject is
daily undergoing increase. It is not to be supposed, however,
that the remains of plants are found solely in the Coal-
measures; for though most abundant towards the summit,
they are found in less numbers in all parts of the series.
Wherever found, they belong to the same great types of vege-
tation ; but, before reviewing these, a few words must be said
as to the orgin and mode of formation of coal.

The coal-beds, as before mentioned, occur interstratified
with shales, sandstones, and sometimes limestones; and there
may, within the limits of a single coal-field, be as many as 80
of 100 of such beds, placed one above the other at different
levels, and varying in thickness from a few inches up to 20 or
30 feet. As a general rule, each bed of coal rests upon a bed
of shale or clay, which is termed the " under-clay, " and in
which are found numerous roots of plants; whilst the strata
immediately on the top of the coal may be shaly or sandy,
but in either case are generally charged with the leaves and
stems of plants, and often have upright trunks passing vertically
through them. When we add to this that the coal itself is,
chemically, nearly wholly composed of carbon, and that its
microscopic structure shows it to be composed almost entirely
of fragments of stems, leaves, bark, seeds, and vegetable debris
derived from land-plants, we are readily enabled to understand
how the coal was formed. The " under-clay " immediately
beneath the coal-bed represents an old land-surface — some-
times, perhaps, the bottom of a swamp or marsh, covered
with a luxuriant vegetation; the coal-bed itself represents the
slow accumulation, through long periods, of the leaves, seeds,
fruits, stems, and fallen trunks of this vegetation, now hardened
and compressed into a fraction of its original bulk by the pres-
sure of the superincumbent rocks ; and the strata of sand or
shale above the coal-bed — the so-called " roof " of the coal —
represent sediments quietly deposited as the land, after a long
period of repose, commenced to sink beneath the sea. On
this view, the rank and long-continued vegetation which gave
rise to each coal-bed was ultimately terminated by a slow
depression of the surface on which the plants grew. The
land-surface then became covered by the water, and aqueous
sediments were accumulated to a greater or less thickness upon
the dense mass of decaying vegetation below, enveloping any
trunks of trees which might still be in an erect position, and
preserving between their layers the leaves and branches of

166 HISTORICAL PALEONTOLOGY.

plants brought down from the neighboring land by streams,
or blown into the water by the wind. Finally, there set in a
slow movement of elevation, — the old land again reappeared
above the water; a new and equally luxuriant vegetation
flourished upon the new land-surface ; and another coal-bed
was accumulated, to be preserved ultimately in a similar
fashion. Some few beds of coal may have been formed by
drifted vegetable matter brought down into the ocean by rivers,
and deposited directly on the bottom of the sea; but in the
majority of cases the coal is undeniably the result of the slow
growth and decay of plants in situ ; and as the plants of the
coal are not marine plants, it is necessary to adopt some such
theory as the above to account for the formation of coal-
seams. By this theory, as is obvious, we are compelled to
suppose that the vast alluvial and marshy flats upon which the
coal-plants grew were liable to constantly-recurring oscillations
of level, the successive land-surfaces represented by the suc-
cessive coal-beds of any coal-field being thus successively
buried beneath accumulations of mud or sand. We have no
need, however, to suppose that these oscillations affected large
areas at the same time ; and geology teaches us that local
elevations and depressions of the land have been matters of
constant occurrence throughout the whole of past time.

All the varieties of coal (bituminous coal, anthracite, cannel-
coal, &c.) show a more or less distinct "lamination" — that is
to say, they are more or less obviously composed of successive
thin layers, differing slightly in color and texture. All the
varieties of coal, also, consist chemically of carbon, with vary-
ing proportions of certain gaseous constituents and a small
amount of incombustible mineral or " ash. " By cutting thin
and transparent slices of coal, we are further enabled, by
means of the microscope, to ascertain precisely not only that
the carbon of the coal is derived from vegetables, but also, in
many cases, what kinds of plants, and what parts of these, enter
into the formation of coal. When examined in this way, all
coals are found to consist more or less entirely of vegetable
matter; but there is considerable difference in different coals as
to the exact nature of this. By Professor Huxley it has been
shown that many of the English coals consist largely of ac-
cumulations of rounded discoidal sacs or bags, which are
unquestionably the seed-vessels or " spore-cases " of certain of
the commoner coal-plants (such as the Lepidodendra), The
best bituminous coals seem to be most largely composed of

THE CARBONIFEROUS PERIOD. 167

these spore-cases ; whilst inferior kinds possess a progressively
increasing amount of the dull carbonaceous substance which is
known as " mineral charcoal, " and which is undoubtedly com-
posed of "the stems and leaves of plants reduced to little
more than their carbon. " On the other hand, Principal Daw-
son finds that the American coals only occasionally exhibit
spore-cases to any extent, but consist principally of the cells,
vessels, and fibres of the bark, integumentary coverings, and
woody portions of the Carboniferous plants.

The number of plants already known to have existed during
the Carboniferous period is so great, that nothing more can be
done here than to notice briefly the typical and characteristic
groups of these — such as the Ferns, the Calamites, the Lepido-
dendroids, the Sigillarioids, and the Conifers.

In accordance with M. Brongniart's generalization, that
the Palaeozoic period is, botanically speaking, the " Age of
Acrogens, " we find the Carboniferous plants to be still mainly
referable to the Flowerless or " Cryptogamous " division of the
vegetable kingdom. The flowering or " Phanerogamous "
plants, which form the bulk of our existing vegetation, are hardly
known, with certainty, to have existed at all in the Carbon-
iferous era, except as represented by trees related to the existing
Pines and Firs, and possibly by the Cycads or " false palms. "*
Amongst the " Cryptogams, " there is no more striking or
beautiful group of Carboniferous plants than the Ferns. Re-
mains of these are found all through the Carboniferous, but in
exceptional numbers in the Coal-measures, and include both
herbaceous forms like the majority of existing species, and
arborescent forms resembling the living Tree-ferns of New
Zealand. Amongst the latter, together with some new types,
are examples of the genera Psaronius and Caulopteris, both of
which date from the Devonian. The simply herbaceous ferns
are extremely numerous, and belong to such widely-distributed
and largely-represented genera as Neuropteris, Odontopteris (fig.
108), Alethopteris, Pecopteris, Sphenopteris, Hymenophyllites, &c.

The fossils known as Calamites (fig. 109) are very common
in the Carboniferous deposits, and have given occasion to an
abundance of research and speculation. They present them-
selves as prostrate and flattened striated stems, or as similar

* Whilst the vegetation of the Coal-period was mainly a terrestrial one,
aquatic plants are not unknown. Sea-weeds (such as the Spirophyton
cauda-Galli) are common in some of the marine strata ; whilst coal, accord-
ing to the researches of the Abbe Castracane, is asserted commonly to
contain the siliceous envelope of Diatoms.

i68 HISTORICAL PALEONTOLOGY.

uncompressed stems growing in an erect position, and some-
times attaining a length of twenty feet or more. Externally, the
stems are longitudinally ribbed, with transverse joints at regular
intervals, these joints giving origin to a whorl of branchlets,
which may or may not give origin to similar whorls of smaller
branchlets still. The stems, further, were hollow, with trans-
verse partitions at the joints, and having neither true wood nor
bark, but only a thin external fibrous shell. There can be little
doubt but that the Catamites are properly regarded as colossal
representatives of the little Horse-tails (Equisetacece} of the
present day. They agree with these not only in the general
details of their organization, but also in the fact that the fruit
was a species of cone, bearing " spore-cases " under scales.
According to Principal Dawson, the Calamites "grew in dense

Fig. lOS.—Odontopteris Schlothelmii. Carboniferous, Europe and North America.

brakes on the sandy and muddy flats, subject to inundation,
or perhaps even in water; and they had the power of budding
out from the base of the stem, so as to form clumps of plants,
and also of securing their foothold by numerous cord-like roots
proceeding from various heights on the lower part of the
stem. "

The Lepidodendroids, represented mainly by the genus
Lepidodendron itself (fig. no), were large tree-like plants,
which attain their maximum in the Carboniferous period, but

THE CARBONIFEROUS PERIOD. 169

which appear to commence in the Upper Silurian, are well
represented in the Devonian, and survive in a diminished form
into the Permian. The trunks of the larger species of Lepido-

Tlg. 109.— Catamites cannatformia . Carboniferous Rocks, Europe and
North America.

dendron at times reach a length of fifty feet and upwards, giv-
ing off branches in a regular bifurcating manner. The bark

170 HISTORICAL PALAEONTOLOGY.

is marked with numerous rhombic or oval scars, arranged in
quincunx order, and indicating the points where the long,
needle-shaped leaves were formerly attached. The fruit con-
sisted of cones or spikes, carried at the ends of the branches,
and consisting of a central axis surrounded by overlapping
scales, each of which supports a " spore-case " or seed-vessel.
These cones have commonly been described under the name
of Lepidostrobi. In the structure of the trunk there is nothing
comparable to what is found in existing trees, there being
a thick bark surrounding a zone principally composed of
" scalariform " vessels, this in turn enclosing a large central pith.
In their general appearance the Lipidodendra bring to mind
the existing Araucarian Pines ; but they are true " Crypto-
gams, " and are to be regarded as a gigantic extinct type of the
modern Club-mosses (Lycopodiacea). They are amongst the
commonest and most characteristic of the Carboniferous
plants ; and the majority of the " spore-cases " so commonly
found in the coal appear to have been derived from the cones
of Lepidodendroids.

The so-called Sigillarioids, represented mainly by Sigillaria
itself (fig. in), were no less abundant and characteristic of the
Carboniferous forests than the Lepidodendra. They commence
their existence, so far as known, in the Devonian period, but
they attain their maximum in the Carboniferous; and — unlike
the Lepidodendroids — they are not known to occur in the
Permian period. They are comparatively gigantic in size,
often attaining a height of from thirty to fifty feet or more;
but though abundant and well preserved, great divergence of
opinion prevails as to their, true affinities. The name of Sigil-
larioids (Lat sigilla, 'little seals or images) is derived from the
fact that the bark is marked with seal-like impressions or leaf-
scars (fig. in).

Externally, the trunks of Sigillaria present strong longitud-
inal ridges, with vertical alternating rows of oval leaf-scars
indicating the points where the leaves were originally attached.
The trunk was furnished with a large central pith, a thick
outer bark, and an intermediate woody zone — composed, accord-
ing to Dawson, partly of the disc-bearing fibres so characteristic
of Conifers ; but, according to Carruthers, entirely made up of
the " scalariform " vessels characteristic of Cryptogams. The
size of the pith was very great, and the bark seems to have been
the most durable portion of the trunk. Thus we have evidence
that in many cases the stumps and " stools " of Sigillaria, stand-

THE CARBONIFEROUS PERIOD. 171

ing upright in the old Carboniferous swamps, were completely
hollowed out by internal decay, till nothing but an exterior
shell of bark was left. Often these hollow stumps became

Fig. 110. — Lepidodendron Sternbergii, Carboniferous, Europe. The central figure
represents a portion of the trunk with its branches, much reduced In size. The right-
hand figure is a portion of a branch with the leaves partially attached to It ; and the
left-hand figure represents the end of a branch bearing a cone of fructification.

ultimately filled up with sediment, sometimes enclosing the
remains of galley-worms, land-snails or Amphibians, which

172 HISTORICAL PALEONTOLOGY.

formerly found in the cavity of the trunk a congenial home ;
and from the sandstone or shale now filling such trunks some
of the most interesting fossils of the Coal-period have been
obtained. There is little certainty as to either the leaves or
fruits of Sigillaria, and there is equally little certainty as to the
true botanical position of these plants. By Principal Dawson
they are regarded as being probably flowering plants allied to
the existing " false palms " or " Cycads; " but the high author-
ity of Mr. Carruthers is to be quoted in support of the belief
that they are Cryptogamic, and most nearly allied to the Club-
mosses.

Pig. 111.— Fragment of the external surface of Sigillaria Grceseri, showing the ribs
and leaf-scars. The left-hand figure represents a small portion enlarged. Carbon-
iferous, Europe.

Leaving the botanical position of Sigillaria thus undecided,
we find that it is now almost universally conceded that the
fossils originally described under the name of Stigmaria are
the roots of Sigillaria, the actual connection between the two
having been in numerous instances demonstrated in an unmis-
takable manner. The Stigmarice (fig. 112) ordinarily present
themselves in the form of long, compressed or rounded frag-
ments, the external surface of which is covered with rounded
pits or shallow tubercles, each of which has a little pit or de-
pression in its center. From each of these pits there proceeds,
in perfect examples, a long cylindrical rootlet; but in many
cases these have altogether disappeared. In their internal
structure, Stigmaria exhibits a central pith surrounded by a
sheath of scalariform vessels, the whole enclosed in a cellular

THE CARBONIFEROUS PERIOD.

173

envelope. The Stiginarice are generally found ramifying in
the " under-clay, " which forms the floor of a bed of coal, and
which represents the ancient soil upon which the Sigillaria grew.
The Lepidodendroids and Sigillarioids, though the first were
certainly, and the second possibly, Cryptogamic or flowerless
plants, must have constituted the main mass of the forests of
the Coal period; but we are not without evidence of the exist-
ence at the same time of genuine " trees, " in the technical
sense of this term — namely, flowering plants with large woody

Fig. 112.— Stigmariaficoides. Quarter natural size. Carboniferous.

stems. So far as is certainly known, all the true trees of the
Carboniferous formation were Conifers, allied to the existing
Pines and Firs. They are recognized by the great size and
concentric woody rings of their prostrate, rarely erect trunks,
and by the presence of disc-bearing fibres in their wood, as
demonstrated by the microscope; and the principal genera
which have been recognized are Dadoxylon, Palaoxylon,
Araucarioxylon, and Pinites. Their fruit is not known with
absolute certainty, unless it be represented, as often conjectured,
by Trigonocarpon (fig. 113). The fruits known under this
name are nut-like, often of consider-
able size, and commonly three- or six-
angled. They probably originally
possessed a fleshy envelope ; and if
truly referable to the Conifers, they
would indicate that these ancient
evergreens produced berries instead
of cones, and thus resembled the
modern Yews rather than the Pines.
It seems further, that the great
group of the Cycads, which are nearly allied to the Conifers, and

Flgr. 113. — Trigonocarpon
ovatum, Coal-measures.Brltain.
(After Lindley and Button.)

174 HISTORICAL PALAEONTOLOGY.

which attained such a striking prominence in the Secondary
period, probably commenced its existence during the Coal
period • but these anticipatory forms are comparatively few in
number, and for the most part of somewhat dubious affinities.

CHAPTER XIII.

THE CARBONIFEROUS PERIOD— Continued.
ANIMAL LIFE OF THE CARBONIFEROUS.

We have seen that there exists a great difference as to the
mode of origin of the Carboniferous sediments, some being
purely marine, whilst others are terrestrial ; and others, again,
have been formed in inland swamps and morasses, or in brack-
ish-water lagoons, creeks, or estuaries. A corresponding dif-
ference exists necessarily in the animal remains of these de-
posits, and in many regions this difference is extremely well
marked and striking. The great marine limestones which
characterize the lower portion of the Carboniferous series in
Britain, Europe, and the eastern portion of America, and the
calcareous beds which are found high up in the Carboniferous
in the western States of America, may, and do, often contain
the remains of drifted plants; but they are essentially charac-
terized by marine fossils ; and moreover, they can be demon-
strated bj the microscope to be almost wholly composed of
the remains of animals which formerly inhabited the ocean.
On the other hand, the animal remains of the beds accompany-
ing the coal are typically the r'emains of air-breathing, terres-
trial, amphibious, or aerial animals, together with those which
inhabit fresh or brackish waters. Marine fossils may be found
in the Coal-measures, but they are invariably confined to spe-
cial horizons in the strata, and they indicate temporary depres-
sions of the land beneath the sea. Whilst the distinction here
mentioned is one which cannot fail to strike the observer, it is
convenient to consider the animal life of the Carboniferous as
a whole : and it is simply necessary, in so doing, to remember

THE CARBONIFEROUS PERIOD.

175

that the marine fossils are in general derived from the inferior
portion of the system; whilst the air-breathing, fresh-water, and
brackish-water forms are almost exclusively derived from the
superior portion of the same.

The Carboniferous Protozoans consist mainly of Foramini-
fera and Sponges, The latter are still very insufficiently known,
but the former are very abundant, and belong to very varied
types. Thin slices of the limestones of the period, when ex-
amined by the microscope, very commonly exhibit the shells
of Foraminifera in greater or less plenty. Some limestones,
indeed, are made up of little else than these minute and elegant
shells, often belonging to types, such as the Textularians and
Rotalians, differing little or not at all from those now in exist-
ence. This is the case, for example, with the Carboniferous
Limestone of Spergen Hill in Indiana (fig. 114), which is
almost wholly made up of the spiral shells of a species of
Endothyra. In the same way, though to a less extent the
black Carboniferous marbles of Ireland, (and the similar mar
bles of Yorkshire, the limestones of the west of England and
of Derbyshire, and the great " Scar Limestones " of the north
of England, contain great numbers of Foraminif erous shells ;
whilst similar organisms commonly occur in the shale-beds
associated with the limestones throughout the Lower Carbon-
iferous series. One of the most interesting of the British Car-
boniferous forms is the Sac-
cammina of Mr. Henry Brady,
which is sometimes present in
considerable numbers in the
limestones of Northumberland,
Cumberland, and the west
of Scotland, and which is con-
spicuous for the .comparatively
large size of its spheroidal or
pear-shaped shell (reaching
from an eighth to a fifth of an
inch in size). More widely dis-
tributed are the generally spin-
dle-shaped shells of Fusulina
(fig. 115), which occur in vast
numbers in the Carboniferous
Limestone of Russia, Arme-
nia, the Southern Alps, and
Spain, similar forms occurring in equal profusion in the higher

Fig. 114.— Transparent slice of Carbon-
iferous Limestone, from Spergen Hill, In-
diana, U. S., showing numerous shells of
Endothyra (Rotalia), Baileyl, slightly en-
larged. (Original.)

176 HISTORICAL PALAEONTOLOGY.

limestones which are found in the Coal-measures of the United

States, in Ohio, Illinois,
Indiana, Missouri, &c. Mr.
Henry Brady, lastly, has
shown that we have in the

Nummulina pristina of the
Fig. 115. — Fumllna cylindnca. Carbon- ~ . . .. P

iferous Limestone, Russia. Carboniferous Limestone of

Namur a genuine Nummu-

lite, precursor of the great important family of the Tertiary
Nummulites.

The sub-kingdom of the Ccelenterates, so far as certainly
known, is represented only by Corals ; * but the remains of
these are so abundant in many of the limestones of the Car-
boniferous formation as to constitute a feature little or not at
all less conspicuous than that afforded by the Crinoids. As is
the case in the preceding period, the Corals belong, almost
exclusively, to the groups of the Rugosa and Tabulata; and
there is a general and striking resemblance and relationship
between the coral-fauna of the Devonian as a whole, and that
of the Carboniferous. Nevertheless, there is an equally decided
and striking amount of difference between these successive
faunas, due to the fact that the great majority of the Carbon-
iferous species are new ; whilst some of the most characteristic
Devonian genera have nearly or quite disappeared, and several
new genera now make their appearance for the first time.
Thus, the characteristic Devonian types Heliophyllum, Pachy-
phyllum, Chonophyllum, Acervularia, Spongophyllum, Smithia,
Endophyllum, and Cystiphyllum, have now disappeared ; and
the great masses of Favosites which are such a striking feature
in the Devonian limestones, are represented but by one or two
degenerate and puny successors. On the other hand, we meet
in the Carboniferous rocks not only with entirely new genera —
such as Axophyllum, Lophophyllum, and Londsdaleia — but we
have an enormous expansion of certain types which had just
begun to exist in the preceding period. This is especially
well seen in the case of the genus Lithostrotion (fig. 116, fc),
which more than any other may be considered as the predom-
inant Carboniferous group of Corals. All the species of
Lithostrotion are compound, consisting either of bundles of

* A singular fossil has been described by Professor Martin Duncan
and Mr. Jenkins from the Carboniferous rocks under the name of Palao-
corvne, and has been referred to the Hydroid Zoophytes (Corynida).
Doubt, however, has been thrown by other observers on the correctness
of this reference.

THE CARBONIFEROUS PERIOD. 177

loosely-approximated cylindrical stems, or of similar " coral-
lites " closely aggregated together into astraeiform colonies, and
rendered polygonal by mutual pressure. This genus has a
historical interest, as having been noticed as early as in the
year 1699 by Edward Lhwyd; and it is geologically important
from its wide distribution in the Carboniferous rocks of both
the Old and New Worlds. Many species are known, and whole
beds of limestone are often found to be composed of little else
than the skeletons of these ancient corals, still standing upright
as they grew. Hardly less characteristic of the Carboniferous
than the above is the great group of simple "cup-corals," of
which Clisiophyllum is the central type. Amongst types which
commenced in the Silurian and Devonian, but which are still
well represented here, may be mentioned Syringopora (fig. 116,
e), with its colonies of delicate- cylindrical tubes united at in-
tervals by cross-bars; Zaphrentis (fig. 116, rf), with its cup-
shaped skeleton and the well-marked depression (or " fossula ")•
on one side of the calice ; Amplexus (fig. 116, c), with its
cylindrical, often irregularly swollen coral and short septa;
Cyathophyllum (fig. 116, a), sometimes simple, sometimes form-
ing great masses of star-like corallites ; and Chatetes, with its
branched stems, and its minute, "tabulate" tubes (fig. 116, /).
The above, together with other and hardly less characteristic
forms, combine to constitute a coral-fauna which is not only in
itself perfectly distinctive, but • which is of especial interest,
from the fact that almost all the varied types of which it is
composed disappeared utterly before the close of the Carbon-
iferous period. In the first marine sediments of a calcareous
nature which succeeded to the Coal-measures (the magnesian
limestones of the Permian), the great group of the Rugose
corals, which flourished so largely throughout the Silurian, De-
vonian, and Carboniferous periods, is found to have all but
disappeared, and it is never again represented save sporadic-
ally and by isolated forms.

Amongst the Echinoderms, by far the most important forms
are the Sea-lilies and the Sea-urchins — the former from their
great abundance, and the latter from their singular structure ;
but the little group of the " Pentremites " also requires to be
noticed. The Sea-lilies are so abundant in the Carboniferous
rocks, that it has been proposed to call the earlier portion of
the period the " Age of Crinoids." Vast masses of the lime-
stones of the period are " crinoidal, " being more or less ex-
tensively composed of the broken columns, and detached plates

i;8 HISTORICAL PALAEONTOLOGY.

and joints of Sea-lilies, whilst perfect "heads" may be exceed-
ingly rare and difficult to procure. In North America the re-
mains of Crinoids are even more abundant at this horizon than

Fig. 116. — Corals of the Carboniferous Limestone, a, Cyathophyllumparacida, show-
ing young corallites budded forth from the disc of the old one ; a', One of the corallites
of the same, seen in cross-section -, b, Fragment of a mass of Lithostrotion irregulare;
&', One of the corallites of the same, divided transversely ; c, Portion of the simple
cylindrical coral of Amplexus coralloides; c', Transverse section of the same species ;
d, Zaphrentis vermicularis, showing the depression or "fossula" on one side of the
cup ; e, Fragment of a mass of Syringopora ramulosa; /. Fragment of Chcetetes
tumidus ; f , Portion of the surf ace of the same, enlarged. From the Carboniferous
Limestone of Britain and Belgium. (After Thomson, De Koninck, Milne-Edwards
and Haime, and the Author.)

in Britain, and the specimens found seem to be commonly
more perfect. The commonest of the Carboniferous Crinoids
belong to the genera Cyaihocrinus, Actinocrinus, Platycrinus,

THE CARBONIFEROUS PERIOD. 179

(fig. 117), Poteriocrinus, Zeacrinus, and Forbesiocrinus. Closely
allied to the Crinoids, or forming a kind of transition between
these and the Cystideans, is the little group of the " Pentre-
mites, " or Blastoids, (fig. 118). This group is first known to
have commenced its existence in the Upper Silurian, and it
increased considerably in numbers in the Devonian; but it
was in the seas of the Carboniferous period that it attained its
maximum, and no certain representative of the family has been
detected in any later deposits. The " Pentremites " resemble
the Crinoids in having a cup-shaped body (fig. 118, A) enclosed
by closely-fitting calcareous plates, and supported on a short
stem or " column, " composed of numerous calcareous pieces
flexibly articulated together. They differ from the Crinoids,
however, in the fact that the upper surface of the body does
not support the crown of branched feathery " arms, " which are
so characteristic of the latter. On the contrary, the summit of
the cup is closed up in the fashion of a flower-bud, whence the

Fig. 117.— Platycrinua tricontadactylus, Lower Carboniferous. The left-hand
figure shows the calyx, arms, and upper |part of the stem ; and the figure next this
shows the surface of one of the joints of the column. The right-hand figure shows the
proboscis. (After M'Coy.)

technical name of Blastoidea applied to the group (Gr. blastos,
a bud; eldos, form). From the top of the cup radiate five broad,

i8o

HISTORICAL PALAEONTOLOGY.

transversely-striated areas (fig. 118, C), each with a longitudi-
nal groove down its middle ; and along each side of each of
these grooves there seems to have been attached a row of
short jointed calcareous filaments or " pinnules. "

Fig. 118.— A, Pentremites pyriformia, side- view of the body ("calyx "); The same
viewed from below, showing the arrangement of the plates ; C, Body of Pentremites
conoideus, viewed from above. Carboniferous.

A few Star-fishes and Brittle-stars are known to occur in the
Carboniferous rocks; but the only other Echinoderms of this
period which need be noticed are the Sea-urchins (Echinoids).
Detached plates and spines of these are far from rare in the
Carboniferous deposits; but anything like perfect specimens
are exceedingly scarce. The Carboniferous- Sea-urchins agree
with those of the present day in having the body enclosed in
a shell, formed by an enormous number of calcareous plates
articulated together. The shell may be regarded as, typically,
nearly spherical in shape, with the mouth in the center of the
base, and the excretory opening or vent at the summit. In both
the ancient forms and the recent ones, the plates of the shell
are arranged in ten zones which generally radiate from the
summit to the center of the base. In five of these zones —
termed the " ambulacral areas " — the plates are perforated by

THE CARBONIFEROUS PERIOD. 181

minute apertures or " pores, " through which the animal can
protrude the little water-tubes ("tube-feet") by which its loco-
motion is carried on. In the other five zones — the so-called
" inter-ambulacral areas " — the plates are of larger size, and
are not perforated by any apertures. In all the modern Sea-
urchins each of these ten zones, whether perforate or imper-
forate, is composed of two rows of plates; and there are thus
twenty rows of plates in all. In the Palaeozoic Sea-urchins, on
the other hand, the " ambulacral areas " are often like those
of recent forms, in consisting of two rows of perforated plates
(fig. 119); but the "inter-ambulacral areas" are always quite
peculiar in consisting each of three, four, five, or more rows of
large imperforate plates, whilst there are sometimes four or ten
rows of plates in the " ambulacral areas " also : so that there
are many more than twenty rows of plates in the entire shell.
Some of the Palaeozoic Sea-urchins, also, exhibit a very pecu-
liar singularity of structure which is only known to exist in a

Fig. 119. — Palcecfiinut ellipticus, one of the Carboniferous Sea-urchins. The left-
hand figure shows one of the " ambulacral areas " enlarged, exhibiting the perforated
plates. The right-hand figure exhibits a single plate from one of the "inter-ambu-
lacral areas." (After M'Coy.)

very few recently-discovered modern forms (viz., Calveria and
Phormosoma). The plates of the inter-ambulacral areas,
namely, overlap one another in an imbricating manner, so as
to communicate a certain amount of flexibility to the shell ;
whereas in the ordinary living forms these plates are firmly
articulated together by their edges, and the shell forms a rigid
immovable box. The Carboniferous Sea-urchins which ex-
hibit this extraordinary peculiarity belong to the genera Lepi-
dechinus and Lepidesthes, and it seems tolerably certain that

182 HISTORICAL PALAEONTOLOGY.

a similar flexibility of the shell existed to a less degree in
the much more abundant genus Archceocidaris. The Carbon-
iferous Sea-urchins, like the modern ones, possessed movable
spines of greater or less length, articulated to the exterior of
the shell; and these structures are of very common occur-
rence in a detached condition. The most abundant genera
are Archczocidaris and Palcechinus; but the characteristic
American forms belong principally to Melonites, Oligoporus,
and Lepidechinus.

Amongst the Annelides it is only necessary to notice the little
spiral tubes of Spirorbis Carbonarius (fig. 120), which are

Fig. 120.— Spirorbis (Microconchus) Carbonarius, of the natural size, attached to a
fossil plant, and magnified. Carboniferous, Britain and North America. (After
Dawson.)

commonly found attached to the leaves or stems of the Coal-
plants. This fact shows that though the modern species of
Spirorbis are inhabitants of the sea, these old representatives
of the genus must have been capable of living in the brackish
waters of lagoons and estuaries.

The Crustaceans of the Carboniferous rocks are numerous,
and belong partly to structural types with which we are already
familar, and partly to higher groups which come into existence
here for the first time. The gigantic Eurypterids of the Upper
Silurian and Devonian are but feebly represented, and make
their final exit here from the scene of life. Their place, how-
ever, is taken by peculiar forme belonging to the allied group
of the Xiphosura, represented at the present day by the King-
crabs or "Horse-shoe Crabs" (Limulus). Characteristic forms
of this group appear in the Coal-measures both of Europe and
America; and though constituting three distinct genera (Prest-
zvichia, Belinurus, and Euproops), they are all nearly related
to one another. The best known of them, perhaps, is the

THE CARBONIFEROUS PERIOD.

183

Fig. 121 . — Prestwichia rotundata, a Llmuloid
Crustacean. Coal-measures, Britain. (After Henry
Woodward.)

Prestwichia rotundata of Coalbrookdale, here figured (fig. 121).
The ancient and for-
merly powerful order
of the Trilobites also
undergoes its final ex-
tinction here, not sur-
viving the deposition
of the Carboniferous
Limestone series in
Europe, but extending
its range in America
into the Coal-meas-
ures. All the known
Carboniferous forms
are small in size and
degraded in point of
structure, and they
are referable to but
three genera {Phil-
lipsia, GriffitJiides, and
Brachymetopus}, be-
longing to a single family. The Phillipsia seminifera here
figured (fig. 122, a,) is a characteristic species in the old World.
The water-fleas (Ostracoaa) are extremely abundant in the
Carboniferous rocks, whole strata being often made up of little
else than the little bivalved shells of these Crustaceans. Many
of them are extremely small, averaging about the size of a
millet-seed ; but a few forms, such as Entomoconchus Scouleri
(fig. 122, <r), may attain a length of from one to three quarters
of an inch. The old group of the Phyjllopods is likewise still
represented in some abundance, partly by tailed forms of a
shrimp-like appearance, such as Dithyrocaris (fig. 122, d), and
partly by the curious striated Estherice and their allies, which
present a curious resemblance to the true Bivalve Molluscs (fig.
122, &). Lastly, we meet for the first time in the Carboniferous
rocks with the remains of the highest of all the groups of
Crustaceans — namely, the so-called " Decapods, " in which there
are five pairs of walking-limbs, and the hinder end of the body
("abdomen") is composed of separate rings, whilst the anterior
end is covered by a head-shield or " carapace. " All the Carbon-
iferous Decapods hitherto discovered resemble the existing
Lobsters, Prawns, and Shrimps (the Macrura), in having a long
and well-developed abdomen terminated by an expanded tail-fin.

i84

HISTORICAL PALEONTOLOGY.

The Palaocaris typus (fig. 122, e} and the Anthrapalamon gracilis
(fig. 122, /), from the Coal-measures of Illinois, are two of the
best understood and most perfectly preserved of the few known
representatives of the " Long-tailed " Decapods in the Car-
boniferous series. The group of the Crabs or " Short-tailed "
Decapods (Brachyura), in which the abdomen is short, not
terminated by a tail-fin, and tucked away out of sight beneath
the body, is at present not known to be represented at all in
the Carboniferous deposits.

In addition to the water-inhabiting group of the Crustaceans,
we find the articulate animals to be represented by members

Fig. 122. — Crustaceans of the Carboniferous Rocks, a, Philllpsia seminifera, of the
natural size— Mountain Limestone, Europe ; 6, One valve of the shell of Estfieria
tenella, of the natural size and enlarged — Coal-measures. Europe ; c, Bivalved shell of
Entonwconchu* Scoulert, of the natural size— Mountain Limestone, Europe ;d, Dlthyro-
caris Scouleri, reduced in size— Mountain Limestone, Ireland ; e, Palceocaris typus,
slightly enlarged— Coal-measures, North America ; /, Anthrapalcemon gracAlis, of
the natural size— Coal-measures, North America. (After De Koninck, M'Coy, Rupert
Jones, a«d Meek and Worthen.)

belonging to the air-breathing classes of the Arachnida, Myria-
poda, and Insecta. The remains of these, as might have been
expected, are not known to occur in the marine limestones of
the Carboniferous series, but are exclusively found in beds asso-

THE CARBONIFEROUS PERIOD. 185

ciated with the Coal, which have been deposited in lagoons,
estuaries, or marshes, in the immediate vicinity of the land, and
which actually represent an old land-surface. The Arachnids
are at present the oldest known of their class, and are repre-
sented both by true Spiders and Scorpions. Remains of the
latter (fig. 123) have been found both in the Old and New
Worlds, and indicate the existence in the Carboniferous period
of Scorpions differing but very little from existing forms. The
group of the Myriapoda, including the recent Centipedes and
Galley-worms, is likewise represented in the Carboniferous strata,
but by forms in many respects very unlike any that are known
to exist at the present day. The most interesting of these
were obtained by Principal Dawson, along with the bones of
Amphibians and the shells of Land-snails, in the sediment filling
the hollow trunks of Sigillaria, and they belong to the genera

Fig. 123.— Cyclophthalmus senior. A fossil Scorpion from the Coal-ineasures
of Bohemia.

Xylobius (fig. 124) and Archiulus. Lastly, the true insects are
represented by various forms of Beetles (Coleoptera},Orthoptera
(such as Cockroaches), and Neur apterous insects resembling
those which we have seen to have existed towards the close of
the Devonian period. One of the most remarkable of the

186

HISTORICAL PALAEONTOLOGY.

latter is a huge May-fly (Haplophlebium Barnesi, fig. 125), with
netted wings attaining an expanse of fully seven inches, and
therefore much exceeding any existing Ephemerid in point
of size.

The lower groups of the Mollusca are abundantly represented

Fig. 124.— Xylobiiis Sigillarice, a Carboniferous Myriapod. a, A specimen, of the
natural size ; 6, Anterior portion of the same, enlarged ; c. Posterior portion, enlarged.
From the Coal-uieasures of Nova Scotia. (After Dawson.)

in the marine strata of the Carboniferous series by Polyzoans
and Brachiopods. Amongst the former, although a variety of

Fig. 125.—ffaplophlebium Barnesi, a Carboniferous insect, from the Coal-measures
of Nova Scotia. (After Dawson.)

other types are known, the majority still belong to the old
group of the "Lace-corals" (Fenestellida), some of the charac-
teristic forms of which are here figured (fig. 126). The graceful
netted fronds of Fenestella, Retepora, and Polypora(fig. 126 a)

THE CARBONIFEROUS PERIOD.

187

are highly characteristic, as are the slender toothed branches
of Glauconome (fig. 126, b). A more singular form, however, is
the curious Archimedes (fig. 126, c), which is so characteristic
of the Carboniferous formation of North America. In this re-
markable type, the colony consists of a succession of funnel-

Fig. 126.— Carboniferous Polyzoa. a, Fragment of Polypora dendroidea, of the
natural size, Ireland ; a' Small portion of the same, enlarged to show the cells ; 6,
Glauconome pulcherrima, a fragment, of the natural size, Ireland ; V, Portion of the
same, enlarged ; c, The central screw-like axis of Archimedes Wortheni, of the natural
size — Carboniferous, America ; c', Portion of the exterior of the , frond of the same,
enlarged ; c". Portion of the interior of the frond of the same showing the mouths of
the cells, enlarged. (After M'Coy and Hall. )

shaped fronds, essentially similar to Fenestella in their structure,
springing in a continuous spiral from a strong screw-like vertical
axis. The outside of the fronds is simply striated ; but the
branches exhibit on the interior the mouths of the little cells

i88 HISTORICAL PALEONTOLOGY.

in which the semi-independent beings composing the colony
originally lived.

The Brachiopods are extremely abundant, and for the most
part belong to types which are exclusively or principally
Palaeozoic in their range. The old genera Strophomena, Orthis
(fig. 127, c~), Athyris (fig. 127, e), Rhynchonella (fig. 127, g), and
Spirifera (fig. 127, /?), are still well represented — the latter, in
particular, existing under numerous specific forms, conspicuous
by their abundance and sometimes by their size. Along with
these ancient groups, we have representatives — for the first time
in any plenty — of the great genus Terebratula (fig. 127, d),
which underwent a great expansion during later periods, and
still exists at the present day. The most characteristic Car-
boniferous Brachiopods, however, belong to the family of the
Productida, of which the principal genus is Producta itself.
This family commenced its existence in the Upper Silurian
with the genus Chonetes, distinguished by its spinose hinge-
margin. This genus lived through the Devonian, and flourished
in the Carboniferous (fig. 127, /). The genus Producta itself,
represented in the Devonian by the nearly allied Productella,
appeared first in the Carboniferous, at any rate in force, and
survived into the Permian ; but no member of this extensive
family has yet been shown to have over-lived the Palaeozoic
period. The Producta of the Carboniferous are not only ex-
ceedingly abundant, but they have in many instances a most
extensive geographical range, and some species attain what
may fairly be considered gigantic dimensions. The shell (fig.
127, a and b} is generally more or less semicircular, with a
straight hinge-margin, and having its lateral angles produced
into larger or smaller ears (hence its generic name — " cochlea
producta"). One valve (the ventral) is usually strongly convex,
whilst the other (the dorsal) is flat or concave, the surface of
both being adorned with radiating ribs, and with hollow
tubular spines, often of great length. The valves are not
locked together by teeth, and there is no sign in the fully-
grown shell of an opening in or between the valves for the
emission of a muscular stalk for the attachment of the shell to
foreign objects. It is probable, therefore, that the Producta,
unlike the ordinary Lamp-shells, lived an independent exist-
ence, their long spines apparently serving to anchor them
firmly in the mud or ooze of the sea-bottom; but Mr. Robert
Etheridge, jun., has recently shown that in one species the
spines were actually employed as organs of adhesion, whereby

THE CARBONIFEROUS PERIOD.

189

the shell was permanently attached to some extraneous object,
such as the stem of a Crinoid. The two species here figured
are interesting for their extraordinarily extensive geographical
range — Producta semireticulata (fig. 127, o) being found in the
Carboniferous rocks of Britain, the continent of Europe,
Central Asia, China, India, Australia, Spitsbergen, and North
and South America; whilst P. longispina (fig. 127, b) has a
distribution little if at all less wide.

Fig. 127 —Carboniferous BracMopoda a, Producta semiretic-ulala, showing th*
slightly concave dorsal valve ; a' Side view of the same, showing the convex ventral valve ;
b, Producta longispina, c, Orthia resupinata ; d, Terebratula fiattata; e, Athyria subtil-
ita; /, Cho?ietf8 Harclre nuts , g, Rhynchonellapleurodon; h, Spirtfera trigonalia. Most
of these forms are widely distributed in the Carboniferous Limestone of Britain,Europe,
America, &c. All the figures are of the natural size. (After Davidson, De Koninck, and
Meek.)

The higher Mollusca are abundantly represented in the
Carboniferous rocks by Bivalves (Lamellibranchs), Univalves
(Gasteropoda), Winged-snails (Pteropoda), and Cephalopods.
Amongst the Bivalves we may note the great abundance of

HISTORICAL PALEONTOLOGY.

Scallops (Aviculopecten and other allied forms), together with
numerous other types — some of ancient origin, others repre-
sented here for the first time. Amongst the Gasteropods, we
find the characteristically Palaeozoic genera Macrocheilus and
Loxonema, the almost exclusively Palaeozoic Euomphalus, and
the persistent genus Pleurotomaria; whilst the free-swimming
Univalves (Heteropoda) are represented by Bellerophon and Por-
cellia, and the Pteropoda by the old genus Conularia. With regard
to the Carboniferous Univalves, it is also of interest to note here
the first appearance of true air-breathing or terrestrial Molluscs,
as discovered by Dawson and Bradley in the Coal-measures of
Nova Scotia and Illinois. Some of these (Conulus priscus) are
true Land-snails, resembling the existing Zonites; whilst others
(Pupa vetusta, fig. 128) appear to be generically inseparable
from the " Chrysalis-shells "
(Pupa) of the present day.
All the known forms — three
in number — are of small size,
and appear to have been local
in their distribution or in their
preservation. More import-
ant, however, than any of the
preceding, are the Cephalo-
poda, represented, as before,
exclusively by the chambered
shells of the Tetrabranchiates.
The older and simpler type of
these, with simple plain septa,
and mostly a central siphuncle,
is represented by the straight
conical shells of the ancient
genus Orthoceras, and the bow-
shaped shells of the equally
ancient Cyrtoceras — some of
the former attaining a great size.
The spirally-curved discoidal

shells of the persistent genus Nautilus are also not unknown,
and some of these likewise exhibit very considerable dimen-
sions. Lastly, the more complex family of the Ammonitida,
with lobed or angulated septa, and a dorsally-placed siphuncle
(situated on the convex side of the curved shells), now for the
first time commences to acquire a considerable prominence.
The principal representative of this group is the genus Gonia-

Flg. 128.— Pupa (Dendropupa) vetusta,
a Carboniferous Land-snail from theCoal-
measures of Nova Scotia, a, The shell, of
the natural size ; 6, The same, magnified;
c, Apex of the shell, enlarged ; d, Portion
of the surface, enlarged. (Alter Dawson.)

THE CARBONIFEROUS PERIOD.

191

tites (fig. 129), which commenced its existence in the Upper
Silurian, is well represented in the De-
vonian, and attains its maximum here.
In this genus, the shell is spirally
curved, the septa are strongly lobed
or angulated, though not elaborately
frilled as in the Ammonites, and the
siphuncle is dorsal. In addition to
Goniatites, the shells of true Ammon-
ites, so characteristic of the Secondary
period, have been described by Dr.
Waagen as occurring in the Carbon-
iferous rocks of India.

Fig. 129.— Gonlatitet (Aganides) Jossce. Carboniferous Limestone.

Coming finally to the Vertcbrata, we have in the first place
to very briefly consider the Carboniferous fishes. These are
numerous; but, with the exception of the still dubious " Cono-
donts, " belong wholly to the groups of the Ganoids and the
Placoids (including under the former head remains which per-
haps are truly referable to the group of the Dipnoi or Mud-
fishes). Amongst the Ganoids, the singular buckler-headed
fishes of the Upper Silurian and Devonian (Cephalaspida) have
apparently disappeared; and the principal types of the Car-
boniferous belong to the groups respectively represented at
the present day by the Gar pike (Lepidosteus} of the North
American lakes, and the Polypterus of the rivers of Africa. Of

192

HISTORICAL PALEONTOLOGY.

the former, the genera Pal&oniscus and Amblypterus (fig. 130),
with their small rhomboidal and enamelled scales, and their
strongly unsymmetrical tails, are perhaps the most abundant.
Of the latter, the most important are species belonging to

Fig. 130. — Amblypterua macropterus. Carboniferous.

the genera Megalichthys and Rhizodus, comprising large fishes,
with rhomboidal scales, unsymmetrical .(" heterocercal ") tails,
and powerful conical teeth. These fishes are sometimes said
to be " sauroid, " from their presenting some Reptilian features
in their organization, and they must have been the scourges
of the Carboniferous seas. The remains of Placoid fishes in
the Carboniferous strata are very numerous, but consist wholly
of teeth and fin-spines, referable to forms more or less closely
allied to our existing Port Jackson Sharks, Dog-fishes, and
Rays. The teeth are of very various shapes and sizes, — some
with sharp, cutting edges (Petalodus, Cladodus, &c.) ; others in
the form of broad crushing plates, adapted, like the teeth of the
existing Port Jackson Shark (Cestracion Philip pi), for breaking
down the hard shells of Molluscs and Crustaceans. Amongst
the many kinds of these latter, the teeth of Psammodus and
Cochliodus (fig. 131) may be mentioned as specially charac-
teristic. The fin-spines are mostly similar to those so common
in the Devonian deposits, consisting of hollow defensive spines
implanted in front of the pectoral or other fins, usually slightly
curved, often superficially ribbed or sculptured, and not un-
commonly serrated or toothed. The genera Ctenacanthus,
Gyracanthus, Homacanthus, &c., have been founded for the
reception of these defensive weapons, some of which indicate
fishes of great size and predaceous habits.

In the Devonian rocks we meet with no other remains of

THE CARBONIFEROUS PERIOD. 193

Vertebrated animals save fishes only; but the Carboniferous
deposits have yielded re-
mains of the higher group
of the Amphibians. This
class, comprising our ex-
isting Frogs, Toads, and
Newts, stands to some ex-
tent in a position midway
between the class of the
fishes- and that of the true
reptiles, being distinguished
from the latter by the fact mg 131 .-Teeth of CochUodw, contort™.
that its members invariably Carboniferous Limestone, Britain,

possess gills in their early

condition, if not throughout life; whilst they are separated from
the former by always possessing true lungs when adult, and
by the fact that the limbs (when present at all) are never in
the form of fins. The Amphibians, therefore, are all water-
breathers when young, and have respiratory organs adapted
for an aquatic mode of life; whereas, when grown up, they
develop lungs, and with these the capacity for breathing air
directly. Some of them, like the Frogs and Newts, lose their
gills altogether on attaining the adult condition ; but others,
such as the living Proteus and Menobranchus, retain their gills
even after acquiring their lungs, and are thus fitted indiffer-
ently for an aquatic or terrestrial existence. The name of
" Amphibia, " though applied to the whole class, is thus not
precisely appropriate except to these last-mentioned forms
(Gr. amphi, both; bios, life). The Amphibians also differ
amongst themselves according as to whether they keep per-
manently the long tail which they all possess when young (as
do the Newts and Salamanders), or lose this appendage when
grown up (as do the Frogs and Toads). Most of them have
naked skins, but a few living and many extinct forms have
hard structures in the shape of scales developed in the integu-
ment. All of them have well-ossified skeletons, though some
fossil types are partially deficient in this respect; and all of
them which possess limbs at all have these appendages sup-
ported by bones essentially similar to those found in the limbs
of the higher Vertebrates. All the Carboniferous Amphibians
belong to a group which has now wholly passed away — namely,
that of the Labyrinthodonts. In the marine strata which form
the base of the Carboniferous series these creatures have only
13

194

HISTORICAL PALEONTOLOGY.

been recognized by their curious hand-shaped footprints, similar
in character to those which occur in the Triassic rocks, and which
will be subsequently spoken of under the name of Cheirotherium.
In the Coal-measures of Britain, the continent of Europe, and
North America, however, many bones of these animals have
been found, and we are now tolerably well acquainted with a
considerable number of forms. All of them seem to have be-
longed to the division of Amphibians in which the long tail
of the young is permanently retained; and there is evidence
that some of them kept the gills also throughout life. The
skull is of the characteristic Amphibian type (fig. 132, a), with
two occipital condyles, and having its surface singularly pitted
and sculptured; and the vertebrae are hollowed out at both
ends. The lower surface of the body was defended by an
armor of singular integumentary shields or scales (fig. 132, c) ;
and an extremely characteristic feature (from which the entire

Pig. 132.— a, Upper surf ace of the skull of Anthracoaaurus RvAselU, one-sixth of the
natural size ; 6, Part of one of the teeth cut across, and highly magnified to show the
characteristic labyrinthine structure ; c, One of the integumentary shields or scales,
one-half of the natural size. Coal-measures, Northumberland. (After Atthey.)

group derives its name) is, that the walls of the teeth are deeply
folded, so as to give rise to an extraordinary " labyrinthine "
pattern when they are cut across (fig. 132, b). Many of the

THE CARBONIFEROUS PERIOD. 195

Carboniferous Labyrinthodonts are of no great size, some of
them very small, but others attain comparatively gigantic
dimensions, though all fall short in this respect of the huge
examples of this group which occur in the Trias. One of the
largest, and at the same time most characteristic, forms of the
Carboniferous series, is the genus Anthracosaurus, the skull of
which is here figured.

No remains of the true Reptiles, Birds, or Quadrupeds have
as yet been certainly detected in the Carboniferous deposits in
any part of the world. It should, however, be mentioned,
that Professor Marsh, one of the highest authorities on the
subject, has described from the Coal-formation of Nova Scotia
certain vertebrae which he believes to have belonged to a
marine reptile (Eosaurus Acadianus}, allied to the great
Ichthyosauri of the Lias. Up to this time no confirmation
of this determination has been obtained by the discovery of
other and more unquestionable remains, and it therefore remains
doubtful whether these bones of Eosaurus may not really belong
to large Labyrinthodonts.

LITERATURE.

The following list contains some of the more important of the
original sources of information to which the student of Carbonif-
erous rocks and fossils may refer : —

(1) 'Geology of Yorkshire,' vol. ii. ; 'The Mountain Lime-

stone District. ' John Phillips.

(2) ' Siluria. ' Sir Roderick Murchison.

(3) ' Memoirs of the Geological Survey of Great Britain and

Ireland. '

(4) ' Geological Report on Londonderry, ' &c. Portlock.

(5) ' Acadian Geology. ' Dawson.

(6) ' Geology of Iowa. ' vol. i. James Hall.

(7) 'Reports of the Geological Survey of Illinois' (Geology

and Palaeontology). Meek, Worthen, &c.

(8) 'Reports of the Geological Survey of Ohio' (Geology

and Palaeontology). Newberry, Cope, Meek, Hall, &c.

(9) * Description des Animaux fossiles qui se trouvent dans le

Terrain Carbonif ere de la Belgique, ' 1843 ; with sub-
sequent monographs on the genera Prnductus and
Chonetcs, on Crinoids, on Corals, &c. De Koninck.

(10) 'Synopsis of the Carboniferous Fossils of Ireland.'

M'Coy.
(n) 'British Palaeozoic Fossils.' M'Coy.

(12) 'Figures of Characteristic British Fossils.' Baily.

(13) 'Catalogue of British Fossils.' Morris.

(14) ' Monograph of the Carboniferous Brachiopoda of Britain

(Palaeontographical Society). Davidson.

(15) 'Monograph of the British Carboniferous Corals'

Palaeontographical Society). Milne-Edwards and Haime.

196 HISTORICAL PALEONTOLOGY.

(16) 'Monograph of the Carboniferous Bivalve Entomos-

traca of Britain' ( Palseontographical Society). Rupert
Jones, Kirkby, and George S. Brady.

(17) ' Monograph of the Carboniferous Foraminifera of

Britain' (Palseontographical Society). H. B. Brady.

(18) "On the Carboniferous Fossils of the West of Scotland"
— ' Trans. Geol. Soc., ' of Glasgow, vol. iii., Supplement.
Young and Armstrong.

(19) ' Poissons Fossiles. ' Agassiz.

(20) " Report on the Labyrinthodonts of the Coal-meas-

ures " — ' British Association Report, ' 1873. L. C. Miall.

(21) 'Introduction to the Study of Palaeontological Botany.'

John Hutton Balfour.

(22) ' Traite de Paleontologie Vegetale. ' Schimper.

(23) ' Fossil Flora. ' Lindley and Hutton.

(24) ' Histoire des Vegetaux Fossiles. ' Brongniart.

(25) 'On Calamites and Calamodendron ' (Monographs of

the Palaeontographical Society). Binney.

(26) ' On the Structure of Fossil Plants found in the Carbonif-

erous Strata ' (Palseontographical Society). Binney.
Also numerous memoirs by Huxley, Davidson, Martin Duncan,
Professor Young, John Young, R. Etheridge, jun. ; Baily, Car-
ruthers, Dawson, Binney, Williamson, Hooker, Jukes, Geikie,
Rupert Jones, Salter, and many other British and Foreign
observers.

CHAPTER XIV.

THE PERMIAN PERIOD.

The Permian formation closes the long series of the Palaeo-
zoic deposits, and may in some respects be considered as a
kind of appendix to the Carboniferous system, to which it can-
not be compared in importance, either as regards the actual
bulk of its sediments or the interest and variety of its life-
record. Consisting, as it does, largely of red rocks — sand-
stones and marls — for the most part singularly destitute of
organic remains, the Permian rocks have been regarded as a
lacustrine or fluviatile deposit; but the presence of well-devel-
oped limestones with indubitable marine remains entirely
negatives this view. It is, however, not improbable that we
are presented in the Permian formation, as known to us at
present, with a series of sediments laid down in inland seas of
great extent, due to the subsidence over large areas of the
vast land-surfaces of the Coal-measures. This view, at any
rate, would explain some of the more puzzling physical char-
acters of the formation, and would not be definitely negatived
by any of its fossils.

A large portion of the Permian series, as already remarked,

THE PERMIAN PERIOD. 197

consists of sandstones and marls, deeply reddened by peroxide
of iron, and often accompanied by beds of gypsum or deposits
of salt. In strata of this nature few or no fossils are found;
but their shallow-water origin is sufficiently proved by the
presence of the footprints of terrestrial animals, accompanied
in some cases by well-defined " ripple-marks. " Along with
these are occasionally found massive breccias, holding larger
or smaller blocks derived from the older formations; and these
have been supposed to represent an old " boulder-clay, " and
thus to indicate the prevalence of an arctic climate. Beds of
this nature must also have been deposited in shallow water.
In all regions, however, where the Permian formation is well
developed, one of its most characteristic members is a Mag-
nesian limestone, often highly and fantastically concretionary,
but containing numerous remains of genuine marine animals,
and clearly indicating that it was deposited beneath a mod-
erate depth of salt water.

It is not necessary to consider here whether this formation
can be retained as a distinct division of the geological series.
The name of Permian was given to it by Sir Roderick Murchi-
son, from the province of Perm in Russia, where rocks of this
age are extensively developed. Formerly these rocks were
grouped with the succeeding formation of the Trias under the
common name of " New Red Sandstone. " This name was
given them because they contain a good deal of red sandstone,
and because they are superior to the Carboniferous rocks,
while the Old Red Sandstone is inferior. Nowadays, how-
ever, the term " New Red Sandstone " is rarely employed,
unless it be for red sandstones and associated rocks, which
are seen to overlie the Coal-measures, but which contain no
fossils by which their exact age may be made out. Under
these circumstances, it is sometimes convenient to employ the
term " New Red Sandstone. " The New Red, however, of the
older geologists, is now broken up into the two formations of
the Permian and Triassic rocks — the former being usually con-
sidered as the ,top of the Palaeozoic series, and the latter con-
stituting the base of the Mesozoic.

In many instances, the Permian rocks are seen to repose
unconformably upon the underlying Carboniferous, from which
they can in addition be readily separated by their lithological
characters. In other instances, however, the Coal-measures
terminate upwards in red rocks, not distinguishable by their
mineral characters from Permian; and in other cases no

198 HISTORICAL PALAEONTOLOGY.

physical discordance between the Carboniferous and Per-
mian strata can be detected. As a general rule, also, the
Permian rocks appear to pass upwards conformably into the
Trias. The division, therefore, between the Permian and Tri-
assic rocks, and consequently between the Palaeozoic and Me-
sozoic series, is not founded upon any conspicuous or universal
physical break, but upon the difference in life which is ob-
served in comparing the marine animals of the Carboniferous
and Permian with those of the Trias. It is to be observed, how-
ever, that this difference can be solely due to the fact that the
Magnesian Limestone of the Permian series presents us with
only a small, and not a typical, portion of the marine deposits
which must have been accumulated in some area at present
unknown to us during the period which elapsed between the
formation of the great marine limestones of the Lower Carbon-
iferous and the open-sea and likewise calcareous sediments of
the Middle Trias.

The Permian rocks exhibit their most typical features in
Russia and Germany, though they are very well developed in
parts of Britain, and they occur in North America. When
well developed, they exhibit three main divisions : a lower set
of sandstones, a middle group, generally calcareous, and an
upper series of sandstones, constituting respectively the Lower,
Middle, and Upper Permians.

In Russia, Germany, and Britain, the Permian rocks con-
sist of the following members : —

1. The Lower Permians, consisting mainly of a great series
of sandstones, of different colors, but usually red. The base
of this series is often constituted by massive breccias with
included fragments of the older rocks, upon which they may
happen to repose; and similar breccias sometimes occur in
the upper portion of the series as well. The thickness of this
group varies a good deal, but may amount to 3000 or 4000
feet.

2. The Middle Permians, consisting, in their typical de-
velopment, of laminated marls, or " marl-slate, " surmounted
by beds of magnesian limestone (the " Zechstein " of the Ger-
man geologists). Sometimes the limestones are degenerate or
wholly deficient, and the series may consist of sandy shales
and g)^psiferous clays. The magnesian limestone, however, of
the Middle Permians is, as a rule, so well marked a feature
that it was long spoken of as the Magnesian Limestone.

3. The Upper Permians, consisting of a series of sandstones

THE PERMIAN PERIOD.

199

and shales, or of red or mottled marls, often gypsiferous, and
sometimes including becjs of limestone.

In North America, the Permian rocks appear to be confined
to the region west of the Mississippi, being especially well de-
veloped in Kansas. Their exact limits have not as yet been
made out, and their total thickness is not more than a few
hundred feet. They consist of sandstones, conglomerates,
limestones, marls, and beds of gypsum. ,

The following diagrammatic section shows the general
sequence of the Permian deposits in the north of England,
where the series is extensively developed (fig. 133) : —

GENERALIZED SECTION OF THE PERMIAN ROCKS IN
THE NORTH OF ENGLAND.

Fig. 133.

,»,.. I Upper Red Sand-
1 stones and Marls.

•• Magnesian Limestone.

Marl Slate.

( Lower Red Sand-
{ stones and Breccias.

— - Coal-measures.

200

HISTORICAL PALEONTOLOGY.

The record of the life of the Permian period is but a scanty
one, owing doubtless to the special peculiarities of such of the
deposits of this age with which we are as yet acquainted. Red
rocks are, as a general rule, more or less completely unfossil-
iferous, and sediments of this nature are highly characteristic of
the Permian. Similarly, magnesian limestones are rarely as
highly charged with organic remains as is the case with normal
calcareous deposits, especially when they have been subjected
to concretionary action, as is observable to such a marked ex-
tent in the Permian limestones. Nevertheless, much interest
is attached to the organic remains, as marking a kind of transi-
tion-period between the Palaeozoic and Mesozoic epochs.

The plants of the Permian period, as a whole, have a dis-
tinctly Palaeozoic aspect, and are far more nearly allied to those
of the Coal-measures than they are to those of the earlier
Secondary rocks ; though the Permian species are mostly dis-
tinct from the Carboniferous, and there are some new genera.
Thus, we find species of Lepidodendron, Catamites, Equisetites,
Asterophyllites, Annularia, and other highly characteristic
Carboniferous genera. On the other hand, the Sigillarioids of
the Coal seem to have finally disappeared at the close of the

Fig. 134.— Walchia pinijormis, from the Permian of Saxony,
a, Branch ; b, Twig. (After Gutbier.)

Carboniferous period. Ferns are abundant in the Permian
rocks, and belong for the most part to the well-known Carbon-
iferous genera Alethopteris, Neuropteris, Sphenopteris, and Pecop-
teris. There are also Tree-ferns referable to ancient genus
Psaronius. The Conifers of the Permian period are numerous,

THE PERMIAN PERIOD. 201

and belong in part to Carboniferous genera. A characteristic
genus, however, is Walchia (fig. 134), distinguished by its lax
short leaves. This genus, though not exclusively Permian, is
mainly so, the best-known species being the W. piniformis.
Here, also, we meet with Conifers which produce true cones,
and which differ, therefore, in an important degree from the
Taxoid Conifers of the Coal-measures. Besides Walchia, a
characteristic form of these is the Ullmania selaginoides, which
occurs in the Magnesian Limestone of Durham, the Middle
Permian of Westmorland, and the " Kupfer-schiefer " of Ger-
many. The group of the Cycads, which we shall subsequently
find to be so characteristic of the vegetation of the Secondary
period, is, on the other hand, only doubtfully represented in
the Permian deposits by the singular genus Nceggerathia.

The Protozoans of the Permian rocks are few in number, and
for the most part imperfectly known. A few Foraminifera have
been obtained from the Magnesian Limestone of England,
and the same formation has yielded some ill-understood
Sponges. It does not seem, however, altogether impossible
that some of the singular " concretions " of this formation may
ultimately prove to have an organic structure, though others
would appear to be clearly of purely inorganic origin. From
the Permian of Saxony, Professor Geinitz has described two
species of Spongillopsis, which he believes to be most nearly
allied to the existing fresh-water Sponges (Spongilla). This
observation has an interest as bearing upon the mode of de-
position and origin of the Permian sediments.

The Ccelenterates are represented in the Permian by but a
few Corals. These belong partly to the Tabulate and partly
to the Rugose division ; but the latter great group, so abun-
dantly represented in Silurian, Devonian, and Carboniferous
seas, is now extraordinarily reduced in numbers, the British
strata of this age yielding only species of the single genus
Polyccclia. So far, therefore, as at present known, all the
characteristic genera of the Rugose Corals of the Carboniferous
had become extinct before the deposition of the limestones of
the Middle Permian.

The Echinodcrms are represented by a few Crinoids, and by a
Sea-urchin belonging to the genus Eocidaris. The latter genus
is nearly allied to the Archceocidaris of the Carboniferous, so
that this Permian form belongs to a characteristically Palaeozoic
type.

A few Annelides (Spirorbis, Vermilia, &c.) have been de-

202

HISTORICAL PALEONTOLOGY.

scribed, but are of no special importance. Amongst the
Crustaceans, however, we have to note the total absence of
the great Palaeozoic group of the Trilobites; whilst the little
Ostracoda and Phyllopods still continue to be represented.
We have also to note the first appearance here of the " Short-
tailed" Decapods or Crabs (Brachyura), the highest of all the
groups of Crustacea, in the person of Hemitrochiscus paradoxus,
an extremely minute Crab from the Permian of Germany.

Amongst the Mollusca, the remains of Polyzoa may fairly be
said to be amongst the most abundant of all the fossils of the
Permian formation. The principal forms of these are the
fronds of the Lace-corals (Fenestella, Retepora, and Synocladia),
which are very abundant in the Magnesian Limestone of the
north of England, and belong to various highly characteristic
species (such as Fenestella retiformis, Retepora Ehrenbergi, and
Synocladia virgulacea). The Brachiopoda are also represented
in moderate numbers in the Permian. Along with species of
the persistent genera Discina Crania, and Lingula, we still
meet with representatives of the old groups Spirifera, Athyris,
and Streptorhynchus ; and the Carboniferous Products yet
survive under well-marked and characteristic types, though in
much-diminished numbers. The species of Brachiopods here
figured (fig. 135) are characteristic of the Magnesian Limestone
in Britain and of the corresponding strata on the Continent.

Fig. 135. — Brachiopods of the Permian formation, a, Producta horrida; b, Lingula
Credneri; c, Perebratula elongata; dand e, Camarophoria globulina. (After King.)

Upon the whole, the most characteristic Permian Brachiopods
belong to the genera Producta, Strophalosia, and Camaro-
phoria.

The Bivalves (Lamellibranchiata} have a tolerably varied

THE PERMIAN PERIOD.

203

development in the Permian rocks; but nearly all the old
types, except some of those which occur in the Carboniferous,
have now disappeared. The principal Permian Bivalves
belong to the groups of the Pearl Oysters (Aviculida) and the
Trigoniadtf, represented by genera such as Bakewellia and
Schizodus; the true Mussels (Mytilida), represented by species
which have been referred to Mytilus itself; and the Arks
(Arcadce), represented by species of the genera Area (fig. 136)
and Byssoarca. The first and last of these three families have
a very ancient origin ; but the family of the Trigoniadce, though
feebly represented at the present day, is one which attains its
maximum development in the Mesozoic period.

The Univalves (Gasteropoda) are rare, and do not demand
special notice. It may be ob-
served, however, that the Palaeo-
zoic genera Euomphalus, Mur-
chisonia, Loxonema, and
Macrocheilus are still in exist-
ence, together with the per-
sistent genus Pleurotomaria.
Pteropods of the old genera
Theca and Conularia have been
discovered; but the first of
these characteristically Palaeo-
zoic types finally dies out here, Fig. 136.— Area antigua. Permian,
and the second only survives
but a short time longer. Lastly, a few Cephalopods have been

Fig. 137. — Platysomus gibbosua, a " heterocercal " Ganoid, from the
Middle Permian of Russia.

found, still wholly referable to the Tetrabranchiate group, and

204 HISTORICAL PALAEONTOLOGY.

belonging to the old genera Orthoceras and Cyrtoceras and the
long-lived Nautilus.

Amongst Vertebrates, we meet in the Permian period not
only with the remains of Fishes and Amphibians, but also, for
the first time, with true Reptiles. The Fishes are mainly
Ganoids, though there are also remains of a few Cestraciont
Sharks. Not only are the Ganoids still the predominant group
of Fishes, but all the known forms possess the unsymmetrical
(" heterocercal ") tail which is so characteristic of the Palaeozoic
Ganoids. Most of the remains of the Permian Fishes have
been obtained from the " Marl-slate " of Durham and the
corresponding " Kupfer-schief er " of Germany, on the horizon
of the Middle Permian ; and the principal genera of the Ganoids
are Palaoniscus and Platysomus (fig. 137).

The Amphibians of the Permian period belong principally
to the order of the Labyrinthodonls, which commenced to be
represented in the Carboniferous, and has a large development
in the Trias. Under the name, however, of Paloeosiren Beinerti,
Professor Geinitz has described an Amphibian from the Lower
Permian of Germany, which he believes to be most nearly
allied to the existing " Mud-eel " (Siren lacertina} of North
America, and therefore to be related to the Newts and Sala-
manders (Urodela).

Finally, we meet in the Permian deposits with the first un-
doubted remains of true Reptiles. These are distinguished, as
a class, from the Amphibians, by the fact that they are air-
breathers throughout the whole of their life, and therefore are
at no time provided with gills ; whilst they are exempt from
that metamorphosis which all the Amphibia undergo in early
life, consequent upon their transition from an aquatic to a
more or less purely aerial mode of respiration. Their skel-
eton is well ossified ; they usually have horny or bony plates,
singly or in combination, developed in the skin; and their
limbs (when present) are never either in the form of fins or
wings, though sometimes capable of acting in either of these
capacities, and liable to great modifications of form and struc-
ture. Though there can be no doubt whatever as to the occur-
rence of genuine Reptiles in deposits of unquestionable Per-
mian age, there is still uncertainty as to the precise number
of types which may have existed at this period. This uncer-
tainty arises partly from the difficulty of deciding in all cases
whether a given bone be truly Labyrinthodont or Reptilian,
but more especially from the confusion which exists at pres-

THE PERMIAN PERIOD.

205

ent between the Permian and the overlying Triassic deposits.
Thus there are various deposits in different regions which
have yielded the remains of Reptiles, and which cannot in
the meanwhile be definitely referred either to the Permian
series or to the Trias by clear stratigraphical or palseonto-

Fig. l38.—Protoro8auru8 Speneri, Middle Permian, Thuringla, reduced in size.
(After Von Meyer.) [Copied from Dana.]

logical evidence. All that can be done in such cases is to be
guided by the characters of the Reptiles themselves, and to
judge by their affinities to remains from known Triassic or Per-

206 HISTORICAL PALEONTOLOGY.

mian rocks to which of these formations the beds containing
them should be referred; but it is obvious that this method
of procedure is seriously liable to lead to error. In accor-
dance, however, with this, the only available mode of deter-
mination in some cases, the remains of Thecodontosaurus and
Palaosaurus discovered in the dolomitic conglomerates near
Bristol will be considered as Triassic, thus leaving Protoro-
saurus * as the principal and most important representative of
the Permian Reptiles, f The type-species of the genus Pro-
torosaurns is the P. Speneri (fig. 138) of the "' Kupfer-schiefer " of
Thuringia, but other allied species have been detected in the
Middle Permian of Germany and the north of England. This
Reptile attained a length of from three to four feet ; and it has
been generally referred to the group of the Lizards ( Lac ert ilia},
to which it is most nearly allied in its general structure, at the
same time that it differs from all existing members of this group
in the fact that its numerous conical and pointed teeth were
implanted in distinct sockets in the jaws — this being a Croco-
dilian character. In other respects, however, Protorosaurus
approximates closely to the living Monitors (Varanida} ; and
the fact that the bodies of the vertebrae are slightly cupped or
hollowed out at the ends would lead to the belief that the
animal was aquatic in its habits. At the same time, the
structure of the hind-limbs and their bony supports proves
clearly that it must have also possessed the power of progres-
sion upon the land. Various other Reptilian bones have been
described from the Permian formation, of which some are prob-
ably really referable to Labyrinthodonts, whilst others are
regarded by Professor Owen as referable to the order of the
" Theriodonts, " in which the teeth are implanted in sockets,
and resemble those of carnivorous quadrupeds in consisting
of three groups in each jaw (namely, incisors, canines, and
molars). Lastly, in red sandstones of Permian age in Dum-
friesshire have been discovered the tracks of what would ap-

* Though commonly spelt as above, it is probable that the name of
this Lizard was really intended to have been Proterosaurus — from the Greek
prof eras, first ; and saura, lizard : and this spelling is followed by many
writers.

t In ah extremely able paper upon the subject (Quart. Journ. Geol.
Soc., vol. xxvi.), Mr. Etheridge has shown that there are good physical
grounds for regarding the dolomitic conglomerate of Bristol as of Triassic
age, and as probably corresponding in time with the Muschelkalk of the
Continent.

THE PERMIAN PERIOD. 207

pear to have been Chelonians (Tortoises and Turtles) ; but it
would not be safe to accept this conclusion as certain upon the
evidence of footprints alone. The Chelichnus Duncani, how-
ever, described by Sir William Jardine in his magnificent work
on the ' Ichnology of Annandale, ' bears a great resemblance
to the track of a Turtle.

No remains of Birds or Quadrupeds have hitherto been
detected in deposits of Permian age.

LITERATURE.

The following works may be consulted by the student with
regard to the Permian formation and its fossils: —

1 i ) "On the Geological Relations and Internal Structure of

the Magnesian Limestone and the Lower Portions of
the New Red Sandstone Series, &c. " — ' Trans. Geol.
Soc., ' ser. 2, vol. iii. Sedgwick.

(2) ' The Geology of Russia in Europe. ' Murchison, De

Verneuil, and von Keyserling.

(3) ' Siluria. ' Murchison.

(4) ' Das Permische System in Sachsen. ' Geinitz and Gutbier.

(5) 'Die Versteinerungen des Deutschen Zechsteingebirges. '

Geinitz.

(6) ' Die Animalischen Ueberreste der Dyas. ' Geinitz.

(7) ' Monograph of the Permian Fossils of England' Palaeon-

tographical Society). King.

(8) ' Monograph of the Permian Brachiopoda of Britain '

(Palaeontographical Society). Davidson.

(9) "On the Permian Rocks of the North-West of England

and their Extension into Scotland " — ' Quart. Journ.
Geol. Soc., ' vol. xx. Murchison and Harkness.

(10) 'Catalogue of the Fossils of the Permian System of the

Counties of Northumberland and Durham. ' Howse.

(11) ' Petrefacta Germanise. ' Goldfuss.

(12) ' Beitrage zur Petref aktenkunde. ' Miinster.

(13) ' Ein Beitrag zur Palaeontologie des Deutschen Zech-

steingebirges. ' Von Schauroth.

(14) ' Saurier aus dem Kupfer-schiefer der Zechstein-forma-

tion. ' Von Meyer.

(15) 'Manual of Palaeontology.' Owen.

(16) 'Recherches sur les Poissons Fossiles. ' Agassiz.

208 HISTORICAL PALAEONTOLOGY.

(17) ' Ichnology of Annandale. ' Sir William Jardine.

(18) 'Die Fossile Flora der Permischen Formation.' Goeppert

(19) 'Genera et Species I^lantarum Fossilium. ' Unger.

(20) " On the Red Rocks of England of older Date than the

Trias " — ' Quart. Journ. Geol. Soc., ' vol. xxvii. Ramsay.

CHAPTER XV.

THE TRIASSIC PERIOD.

We come now to the consideration of the great Mesozoic, or
Secondary series of formations, consisting, in ascending order,
of the Triassic, Jurassic, and Cretaceous systems. The Trias-
sic group forms the base of the Mesozoic series, and corre-
sponds with the higher portion of the New Red Sandstone of
the older geologists. Like the Permian rocks, and as implied
by its name, the Trias admits of a subdivision into three
groups — a Lower, Middle, and Upper Trias. Of these sub-
divisions the middle one is wanting in Britain; and all have
received German names, being more largely and typically de-
veloped in Germany than in any other country. Thus, the
Lower Trias is known as the Bunter Sandstein; the Middle
Trias is called the Muschelkalk; and the Upper Trias is known
as the Keuper.

I. The lowest division of the Trias is known as the Bunter
Sandstein (the Gres bigarre of the French), from the generally
variegated colors of the beds which compose it (German,
bunt, variegated). The Bunter Sandstein of the continent of
Europe consists of red and white sandstones, with red clays,
and thin limestones, the whole attaining a thickness of about
1500 feet. The term " marl " is very generally employed to
designate the clays of the Lower and Upper Trias ; but the

THE TRIASSIC PERIOD. 209

term is inappropriate, as they may contain no lime, and are
therefore not always genuine marls. In Britain the Bunter
Sandstein consists of red and mottled sandstones, with uncon-
solidated conglomerates, or " pebble-beds, " the whole having
a thickness of 1000 to 2000 feet. The Bunter Sandstein, as
a rule, is very barren of fossils.

II. The Middle Trias is not developed in Britain, but it
is largely developed in Germany, where it constitutes what is
known as the Muschelkalk (Germ. Muschel, mussel; kalk, lime-
stone), from the abundance of fossil shells which it contains.
The Muschelkalk (the Calcaire coquillier of the French) consists
of compact grey or yellowish limestones, sometimes dolomitic,
and including occasional beds of gypsum and rock-salt.

III. The Upper Trias, or Keuper (the Marnes irisees of the
French), as it is generally called, occurs in England; but is
not so well developed as it is in Germany. In Britain, the
Keuper is 1000 feet or more in thickness, and consists of white
and brown sandstones with red marls, the whole topped by
red clays with rock-salt and gypsum.

The Keuper in Britain is extremely unfossiliferous ; but it
passes upwards with perfect conformity into a very remarkable
group of beds, at one time classed with the Lias, and now
known under the names of the Penarth beds (from Penarth, in
Glamorganshire), the Rhaetic beds (from the Rhaetic Alps), or
the Avicula contorta beds (from the occurrence in them of
great numbers of this peculiar Bivalve). These singular beds
have been variously regarded as the highest beds of the Trias,
or the lowest beds of the Lias, or as an intermediate group.
The phenomena observed on the Continent, however, render
it best to consider them as Triassic, as they certainly agree
with the so-called Upper St. Cassian or Kossen beds which
form the top of the Trias in the Austrian Alps.

The Penarth beds occur in Glamorganshire, Gloucestershire,
Warwickshire, Staffordshire, and the north of Ireland; and
they generally consist of a small thickness of grey marls, white
limestones, and black shales, surmounted conformably by the
lowest beds of the Lias. The most characteristic fossils which
they contain are the three Bivalves Cardium Rhceticum, Avicula
contorta, and Pecten Valoniensis; but they have yielded many
other fossils, amongst which the most important are the re-
mains of Fishes and small Mammals (Microlestes).

In the Austrian Alps the Trias terminates upwards in an
extraordinary series of fossiliferous beds, replete with marine
14

210

HISTORICAL PALEONTOLOGY.

fossils. Sir Charles Lyell gives the following table of these
remarkable deposits : —

Strata below the Lias

Kossen beds,

(Synonyms, Up-
per St Cassian
beds of Escher
and Merian.)

2. Dachstein beds.

3. Hallstadt beds
(or St Cassian),

4. A. Guttenstein

beds.
B. Werfen beds,

base of Upper

Trias ?
Lower Trias of

some geologists.

in the Austrian Alps, in descending order.

( Grey and black limestone, with calcar-
eous marls having a thickness of
about 50 feet. Among the fossils,
Brachiopoda very numerous ; some
few species common to the genuine
Lias; many peculiar. Avicula con-
torta, Pecten Valoniensis, Cardium
Rh&ticum, Avicula inaquivalvis, Spir-
ifer Munsteri, Dev. Strata contain-
ing the above fossils alternate with
the Dachstein beds, lying next below.

White or greyish limestone, often in
beds three or four feet thick. Total
thickness of the formation above
2000 feet. Upper part fossiliferous,
with some strata composed of corals
(Lithodendron.) Lower portion with-
out fossils. Among the character-
istic shells are Hemicardium Wulfeni,
Megalodon triqueter, and other large
bivalves.

Red, pink, or white marbles, from 800
to 1000 feet in thickness, containing
more than 800 species of marine fos-
sils, for the most part mollusca. Many
species of Orthoceras. True Am-
monites, besides Ceratites and Gon-
iatites, Belemnites (rare), Porcellia,
Pleurotomaria, Trochus,Monotis Sali-
11 ana, &c

A. Black and grey
limestone 150 feet
thick, alternating with
the underlying Wer-
fen beds.

B. Red and green
shale and sandstone,
with salt and gyp-
sum.

Among the fossils
are Ceratite*
cassianua. My-
acites fassaen-
8i8, Naticella
costata, dec.

J

In the United States, rocks of Triassic age occur in several
areas between the Appalachians and the Atlantic seaboard;
but they show no such triple division as in Germany, and their
exact place in the system is uncertain. The rocks of these
areas consist of red sandstones, sometimes shaly or conglomer-
atic, occasionally with beds of impure limestone. Other more
extensive areas where Triassic rocks appear at the surface, are
found west of the Mississippi, on the slopes of the Rocky Moun-

THE TRIASSIC PERIOD.

211

tains, where the beds consist of sandstones and gypsiferous
marls. The American Trias is chiefly remarkable for having
yielded the remains of small Marsupial (Dromatherium} , and
numerous footprints, which have generally been referred to
Birds (Brontozoum), along with the tracks of undoubted Rep-
tiles (Otosoum, Anisopus, &c.)

The subjoined section (fig. 139) expresses, in a diagram-
matic manner, the general sequence of the Triassic rocks when
fully developed, as, for example, in the Bavarian Alps: —

GENERALIZED SECTION OF THE TRIASSIC ROCKS OF

CENTRAL EUROPE.

Fig. 139-

Upper Keuper (Kos-
sen or Rhsetic beds,
and Dachsteln beds).

'- \ n

i — i — T— T

JLJLJLji

rnr-r

\\' \

1...

Middle Keuper (Hall-
stadt or St. Cassian
beds).

j Lower Keuper (Keuper
I Sandstones proper).

Muschelkalk.

/ Bunter Sandstein. Gut-
tenstein and Werfen
beds?)

With regard to the life of the Triassic period, we have to

212 HISTORICAL PALEONTOLOGY.

notice a difference as concerns the different members of the
group similar to that which has been already mentioned in
connection with the Permian formation. The arenaceous
deposits of the series, namely, resemble those of the Permian,
not only in being commonly red or variegated in their color,
but also in their conspicuous paucity of organic remains.
They for the most part are either wholly unfossiliferous, or
they contain the remains of plants or the bones of reptiles,
such as may easily have been drifted from some neighboring
shore. The few fossils which may be considered as properly
belonging to these deposits are chiefly Crustaceans (Estheria)
or Fishes, which may well have lived in the waters of estuaries
or vast inland seas. We may therefore conclude, with con-
siderable probability, that the barren sandy and marly accumu-
lations of the Bunter Sandstein and Lower Keuper were not
laid down in an open sea, but are probably brackish-water
deposits, formed in estuaries or land-locked bodies of salt
water. This at any rate would appear to be the case as regards
these members of the series as developed in Britain and in
their typical areas on the continent of Europe; and the origin
of most of the North American Trias would appear to be
much the same. Whether this view be correct or not, it is
certain that the beds in question were laid down in shallow
water, and in the immediate vicinity of land, as shown by the
numerous drifted plants which they contain and the common
occurrence in them of the footprints of air-breathing animals
(Birds, Reptiles, and Amphibians). On the other hand, the
middle and the highest members of the Trias are largely calca-
reous, and are replete with the remains of undoubted marine
animals. There cannot, therefore, be the smallest doubt but
that the Muschelkalk and the Rhsetic or Kossen beds were
slowly accumulated in an open sea, of at least a moderate
depth; and they have preserved for us a very considerable
selection from the marine fauna of the Triassic period.

The plants of the Trias are, on the whole, as distinctively
Mesozoic in their aspect as those of the Permian are Palaeo-
zoic. Tn spite, therefore, of the great difficulty which is ex-
perienced in e-ffecting a satisfactory stratigraphical separation
between the Permian and the Trias, we have in this fact a
proof that the two formations were divided by an interval of
time sufficient to allow of enormous changes in the terrestrial
vegetation of the world. The Lepidodendroids, Asterophyllites,
and Annularies, of the Goal and Permian formations, have now

THE TRIASSIC PERIOD. 213

apparently wholly disappeared ; and the Triassic flora consists
mainly of Ferns, Cycads, and Conifers, of which only the two
last need special notice. The Cycads (fig. 140) are true exo-
genus plants, which in general form and habit of growth pre-

Fig. llQ.—Zamia spirali», a living Cycad. Australia.

sent considerable resemblance to young Palms, but which in
reality are most nearly related to the Pines and Firs (Conifers).
The trunk is unbranched, often much shortened, and bears a
crown of feathery pinnate fronds. The leaves are usually
" circinate " — they unroll in expanding, like the fronds of
ferns. The seeds are not protected by a seed-vessel, but are
borne upon the edge of altered leaves, or are carried on the
scales of a cone. All the living species of Cycads are natives
of warm countries, such as South America, the West Indies,
Japan, Australia, Southern Asia, and South Africa. The
remains of Cycads, as we have seen, are not known to occur
in the Coal formation, or only to a very limited extent towards
its close; nor are they known with certainty as occurring in
Permian deposits. In the Triassic period, however, the re-
mains of Cycads belonging to such genera as Pterophyllum
(fig. 141, b), Zamites, and Podozamites (fig. 141 c), are suffi-
ciently abundant to constitute quite a marked feature in the
vegetation ; and they continue to be abundantly represented
throughout the whole Mesozoic series. The name " Age of
Cycads, " as applied to the Secondary epoch, is therefore,
from a botanical point of view, an extremely appropriate one.
The Conifers of the Trias are riot uncommon, the principal
form being Voltzia (fig. 141, a), which possesses some peculiar

214 HISTORICAL PALAEONTOLOGY.

characters, but would appear to be mostly nearly related to the
recent Cypresses.

As regards the Invertebrate animals of the Trias, our knowl-
edge is still principally derived from the calcareous beds
which constitute the center of the system (the Muschelkalk)
on the continent of Europe, and from the St. Cassian and
Rhsetic beds still higher in the series; whilst some of the

Fig. 141. — Trlassic Conifers and Cycads. a, Voltzia (Schizoneura) heterophylla,
portion of a branch, Europe and America ; 6, Part of the frond of Pterophyllum
Jcegeri, Europe ; c, Part of the frond of Podozamites lanceolatus, America.

Triassic strata of California and Nevada have likewise yielded
numerous remains of marine Invertebrates. The Protozoans
are represented by Foraminifera and Sponges, and the C&len-
terates by a small number of Corals; but these require no
special notice. It may be mentioned, however, that the great

THE TRIASSIC PERIOD.

215

Palaeozoic group of the Rugose corals has no known repre-
sentative here, its place being taken by corals of Secondary
type (such as Montlivaltia, Synastraa, &c.)

The Echinoderms are represented principally by Crinoids,
the remains of which are extremely abundant in some of the
limestones. The best-known species is the famous " Lily-
Encrinite" (Encrinus liUiformis, fig. 142), which is character-
istic of the Muschelkalk. In this beautiful species, the flower-
like head is supported upon a rounded stem, the joints of
which are elaborately articulated with one
another; and the fringed arms are com-
posed each of a double series of alter-
nating calcareous pieces. The Palaeozoic
Urchins, with their supernumerary rows of
plates, the Cystideans, and the Pentremites
have finally disappeared; but both Star-
fishes and Brittle-stars continue to be rep-

Fig. 143.

Aipidura loricata, a Triassic Ophlurold.
Muschelkalk, Germany.

Fig. 142. — Head and
upper part of the column
of Encrinus liUiformis.
The lower figure shows
the articulating surface
of one of the joints of the
column. Muschelkalk,
Germany.

period. Remains of

resented. One of the latter — namely, the
Asf>idura loricata of Goldfuss (fig. 143) — is
highly characteristic of the Muschelkalk.

The remains of Articulate Animals are
not very abundant in the Trias, if we except
the bivalved cases of the little Water-fleas
(Ostracoda), which are occasionally very
plentiful. There are also many species
of the horny, concentrically-striated valves
of the Esthericz (see fig. 122, &), which
might easily be taken for small Bivalve
Molluscs. The " Long-tailed " Decapods,
of the type of the Lobster, are not with-
out examples, but they become much more
numerous in the succeeding Juriassic
insects have also been discovered.

216

HISTORICAL PALEONTOLOGY.

Amongst the Mollusca we have to note the disappearance,
amongst the lower groups, of many characteristic Palaeozoic
types. Amongst the Polyzoans, the characteristic " Lace-
corals, " Fenestella, Retepora, * Synocladia, Polypora, &c., have

Fig. 144. — Triassic Lamellibranchs, a, Daonella (Halobia) Lommelli ; b, Pecten
Valoniensis; c, Myophoria lineata; d, Cardium Rhaticum ; e, Avicula contorta;
f, Avicula socialis.

become apparently extinct. The same is true of many of the
ancient types of Brachiopods, and conspicuously so of the
great family of the Productida, which played such an important
part in the seas of the Carboniferous and Permian periods.

Bivalves (Lamellibranchiata) and Univalves (Gasteropoda}
are well represented in the marine beds of the Trias, and
some of the former are particularly characteristic either of the

* The genus Retepora is really a recent one, represented by living
forms ; and the so-called Retepora' of the Palaeozoic rocks should properly
receive another name (Phyllopora), as being of a different nature. The
name Retepora has been here retained for these old forms simply in ac-
cordance with general usage.

THE TRIASSIC PERIOD. 217

formation as a whole or of minor subdivisions of it. A few of
these characteristic species are figured in the accompanying
illustration (fig. 144). Bivalve shells of the genera Daonella
(fig. 144, a) and Halobia (Monotis) are very abundant, and are
found in the Triassic strata of almost all regions. These
groups belong to the family of the Pearl-oysters (Aviculida},
and are singular from the striking resemblance borne by some
of their included forms to the Strophomena amongst the Lamp-
shells, though, of course, no real relation exists between the
two. The little Pearl-oyster, Avicula socialis (fig. 144, /), is
found throughout the greater part of the Triassic series, and is
especially abundant in the Muschelkalk. The genus Myo-
phoria (fig. 144, c), belonging to the Trigoniadce, and related
therefore to the Permian Schizodus, is characteristically Trias-
sic, many species of the genus being known in deposits of this
age. Lastly, the so-called " Rhaetic " or " Kossen " beds are
characterized by the occurrence in them of the Scallop, Pecten
Valoniensis (fig. 144, b) ; the small Cockle, Cardium Rhceticum
(fig. 144, d} ; and the curiously-twisted Pearl-oyster, Avicula
contorta (fig. 144, e) — this last Bivalve being so abundant that
the strata in question are often spoken of as the "Avicula
contorta beds. "

Passing over the groups of the Heteropods and Pteropods,
we have to notice the Cephalopoda, which are represented in
the Trias not only by the chambered shells of Tetrabranchiates,
but also, for the first time, by the internal skeletons of Dibran-
chiate forms. The Trias, therefore, masks the first recognized
appearance of true Cuttle-fishes. All the known examples of
these belong to the great Mesozoic group of the Belemnitida;
and as this family is much more largely developed in the suc-
ceeding Jurassic period, the consideration of its characters
will be deferred till that formation is treated of. Amongst the
chambered Cephalopods we find quite a number of the Palae-
ozoic Orthoceratites, some of them of considerable size, along
with the ancient Cyrtoceras and Goniatites; and these old types,
singularly enough, occur in the higher portion of the Trias
(St. Cassian beds), but have, for some unexplained reason, not
yet been recognized in the lower and equally fossiliferous

218

HISTORICAL PALAEONTOLOGY.

Fig. 145. — Ceratites nodosus, viewed from the side
and from behind. Muschelkalk.

formation of the Muschelkalk. Along with these we meet for
the first time with true Ammonites, which fill such an extensive
place in the Jurassic
seas, and which will
be spoken of here-
after. The form, how-
ever, which is most
characteristic of the
Trias is Ceratites (fig.
145). In this genus
the shell is curved into
a flat spiral, the volu-
tions of which are in
contact ; and it further
agrees with both Go-
niatites and Ammon-
ites in the fact that the
septa or partitions be-
tween the air-cham-
bers are not simple and plain (as in the Nautilus and its allies),
but are folded and bent as they approach the outer wall of the
shell. In the Goniatite these foldings of the septa are of a simply
lobed or angulated nature, and in the Ammonite they are ex-
tremely complex; whilst in the Ceratite there is an inter-
mediate state of things, the special feature of which is, that
those foldings which are turned towards the mouth of the
shell are merely rounded, whereas those which are turned
away from the mouth are characteristically toothed. The
genus Ceratites, though principally Triassic, has recently been
recognized in strata of Carboniferous age in India.

From the foregoing it will be gathered that one of the most
important points in connection with the Triassic Mollusca is
the remarkable intermixture of Palaeozoic and Mesozoic types
which they exhibit. It is to be remembered, also, that this
intermixture has hitherto been recognized, not in the Middle
Triassic limestones of the Muschelkalk, in which — as the
oldest Triassic beds with marine fossils — we should naturally
expect to find it, but in the St. Cassian beds, the age of which
is considerably later than that of the Muschelkalk. The
intermingling of old and new types of Shell-fish in the Upper
Trias is well brought out in the annexed table, given by Sir

THE TRIASSIC PERIOD.

219

Charles Lyell in his 'Student's Elements of Geology' (some
of the less important forms in the table being omitted here) : —

GENERA OF FOSSIL MOLLUSCA IN THE ST. CASSIAN
AND HALLSTADT BEDS.

Common to Older Bocks.

Orthoceras.

Bactrites.

Macrocheilus.

Loxonema.

Holopella.

Murchisonia.

Porcellia.

Athyris.

Retzia.

Cyrtina.

Euomphalus.

Characteristic of Triassic
Rocks.

Common to Newer Bocks.

Ceratites. .

Ammonites.

Cochloceras.

Chemnitzia.

Rhabdoceras.

Cerithium.

Aulacoceras.

Monodonta.

Naticella.

Sphoera.

Platystoma.

Cardita.

Halobia.
Hornesia.

Myoconcha.
Hinnites.

Koninckia.

Monotis.

Scoliostoma.

Plicatula.

Myophoria.

Pachyrisma.

(The last two are

Thecidium.

principally but

not exclusively

Triassic.)

Thus, to emphasize the more important points alone, the Trias
has yielded, amongst the Gasteropods, the characteristically
Palaeozoic Loxoncma, Holopella, Murchisonia, Euomphalus, and
Porcellia, along with typically Triassic forms like Platystoma
and Scoliostoma, and the great modern groups Chemnitzia and
Cerithium. Amongst the Bivalves we find the Palaeozoic
Mcgalodon side by side with the Triassic Halobia and Myo-
phoria, these being associated with the Cardita, Hinnites,
Plicatulce, and Trigonia of later deposits. The Brachiopods
exhibit the Palaeozoic Athyris, Retzia, and Cyrtina, with the
Triassic Koninckia and the modern Thecidium. Finally, it is
here that the ancient genera Orthoceras, Cyrtoceras, and Gonia-
tites make their last appearance upon the scene of life, the
place of the last of these being taken by the more complex
and almost exclusively Triassic Ceratites; whilst the still more
complex genus Ammonites first appears here in force, and is
never again wanting till we reach the close of the Mesozoic
period. The first representatives of the great Secondary
family of the Belemnites are also recorded from this horizon.
Amongst the Vertebrate Animals of the Trias, the Fishes are

220 HISTORICAL PALEONTOLOGY.

represented by numerous forms belonging to the Ganoids and
the Placoids. The Ganoids of the period are still all provided
with unsymmetrical (" heterocercal ") tails, and belong prin-
cipally to such genera as Palaoniscus and Catopterus. The
remains of Placoids are in the form of teeth and spines, the
two principal genera being the two important Secondary
groups Acrodus and Hybodus. Very nearly at the summit
of the Trias in England, in the Rhaetic series, is a singular
stratum, which is well known as the " bone-bed, " from the
number of fish-remains which it contains. More interesting,
however, than the above, are the curious palate-teeth of the
Trias, upon which Agassiz founded the genus Ceratodus. The
teeth of Ceratodus (fig. 146) are singular flattened plates,
composed of spongy bones beneath, covered superficially with
a layer of enamel. Each plate is approximately triangular,
one margin (which we know to be the outer one) being
prolonged into prongs or conical prominences, whilst the
surface ' is more or less regularly undulated. Until recently,
though the master-mind of Agassiz recognized that these
singular bodies were undoubtedly the teeth of fishes, we were
entirely ignorant as to their precise relation to the animal, or

Fig. 146. — a, Dental plate of Ceratodus serratus, Keuper ; b, Dental plate of
Ceratodus altus, Keuper. (After Agassiz.)

as to the exact affinities of the fish thus armed. Lately, how-
ever, there has been discovered in the rivers of Queensland
(Australia) a living species of Ceratodus (C. Fosteri, fig. 147),
with teeth precisely similar to those of its Triassic predecessor;
and we thus have become acquainted with the use of these
structures and the manner in which they were implanted in
the mouth. The palate carries two of these plates, with their
longer straight sides turned towards each other, their sharply-
sinuated sides turned outwards, and their short straight sides

THE TRIASSIC PERIOD. 221

or bases directed backwards. Two similar plates in the lower
jaw correspond to the upper, their undulated surfaces fitting
exactly to those of the opposite teeth. There are also two
sharp-edged front teeth, which are placed in the front of the
mouth in the upper jaw; but these have not been recognized
in the fossil specimens. The living Ceratodus feeds on vege-
table matters, which are taken up or torn off from plants by
the sharp front teeth, and then partially crushed between the
undulated surfaces of the back teeth (Giinther) ; and there
need be little doubt but that the Triassic Ceratodi followed
a similar mode of existence. From the study of the living
Ceratodus, it is certain that the genus belongs to the same
group as the existing Mud-fishes (Dipnoi) ; and we therefore
learn that this, the highest, group of the entire class of Fishes
existed in Triassic times under forms little 01 not at all differ-
ent from species now alive ; whilst it has become probable
that the order can be traced back into the Devonian period.

The Amphibians of the Trias all belong to the old order of

Fig. 147.— Ceratodus Foateri, the Australian Mud-fish, reduced In size.

the Labyrinthodonts, and some of them are remarkable for
their gigantic dimensions. They were first known by their
footprints, which were found to occur plentifully in the Tri-
assic sandstones of Britain and the continent of Europe, and
which consisted of a double series of alternately-placed pairs
of hand-shaped impressions, the hinder print of each pair being
much larger than the one in front (fig. 148). So like were these
impressions to the shape of the human hand, that the at that
time unknown animal which produced them was at once chris-
tened Cheirotherium, or " Hand-beast. " Further discoveries,
however, soon showed that the footprints of Cheirotherium
were really produced by species of Amphibians which, like the
existing Frogs, possessed hind-feet of a much larger size than

222

HISTORICAL PALAEONTOLOGY.

the fore-feet and to which the
name of Labyrinthodonts was
applied in consequence of the
complex microscopic structure of
the teeth (fig. 149). In the essen-
tial details of their structure, the
Triassic Labyrinthodonts did not
differ materially from their pre-
decessors in the Coal-measures
and Permian rocks. They pos-
sessed the same frog-like skulls
(fig. 150), with a lizard-like body,
a long tail, and comparatively
feeble limbs. The hind-limbs
were stronger and longer than
the fore-limbs, and the lower

Fig. 148.— Footprints of a Labyrinthodont (Ckeirotherium), from the Triassic Sand-
stones of Hessberg, near Hildburghausen. Germany, reduced one-eighth. The lower
figure shows a slab, with several prints, and traversed by reticulated sun-cracks ; the
upper figure shows the impression of one of the hind- feet, one-half of the natural size.
(After Sickler.)

THE TRIASSIC PERIOD.

223

surface of the body was protected by an armor of bony plates.
Some of the Triassic Labyrinthodonts must have attained
dimensions utterly unapproached amongst existing Amphibians,
the skull of Labyrinthodon J&geri (fig. 150) being upwards of
three feet in length and two feet in breadth. Restorations of
some of these extraordinary creatures have been attempted in
the guise of colossal Frogs; but they must in reality have more
closely resembled huge Newts.

Remains of Reptiles are very abundant in Triassic deposits,
and belong to very varied types. The most marked feature,
in fact, connected with the Vertebrate fauna of the Trias, and
of the Secondary rocks in general, is the great abundance of
Reptilian life. Hence the Secondary period is often spoken
of as the " Agfe of Reptiles. " Many of the Triassic reptiles
depart widely in their structure from any with which we are
acquainted as existing on the earth at the present day, and it is
only possible here to briefly note some of the more important
of these ancient forms. Amongst the group of the Lizards
(Lacertilia}, represented by Protorosaurus in the older Permian
strata, three types more or less certainly referable to this order
may be mentioned. One of these is a small reptile which

Fig. 149.— Section of the tooth of Labyrinthodon
(Mastodonsaurua) Jcegeri, showing the microscopic
structure. Greatly enlarged. Trias.

Fig. 150.— a, Skull of La-
byrinthodon Jcegeri, much
reduced in size ; 6, Tooth
of the same, Trias, Wurt-
temberg.

was found many years ago in sandstones near Elgin, in Scot-
land, and which excited special interest at the time in conse-
quence of the fact that the strata in question were believed to

224 HISTORICAL PALAEONTOLOGY.

belong to the Old Red Sandstone formation. It is, however,
now certain that the Elgin sandstones which contain Telerpeton
Elginense, as this reptile is termed, are really to be regarded as
of Triassic age. By Professor Huxley, Telerpeton is regarded
as a Lizard, which cannot be considered as " in any sense
a less perfectly-organized creature than the Gecko, whose
swift and noiseless run over walls and ceilings surprises the
traveler in climates warmer than our own. " The " Elgin Sand-
stones " have also yielded another Lizard, which was originally
described by Professor Huxley under the name of Hyperoda-
pedon, the remains of the same genus having been subsequently
discovered in Triassic strata in India and South Africa. The
Lizards of this group must therefore have at one time enjoyed
a very wide distribution over the globe; and the living Spheno-
don of New Zealand is believed by Professor Huxley to be the
nearest living ally of this family. The Hyperodapedon of the
Elgin Sandstones was about six feet in length, with limbs
adapted for terrestrial progression, but with the bodies of the
vertebrae slightly biconcave, and having two rows of palatal
teeth, which become worn down to the bone in old age.
Lastly, the curious Rhynchosaurus of the Trias is also referred,
by the eminent comparative anatomist above mentioned, to the
order of the Lizards. In this singular reptile (fig. 151) the skull

is somewhat bird-like, and the
jaws appear to have been desti-
tute of teeth, and to have been
encased in a horny sheath like
the beak of a Turtle or a Bird.
It is possible, however, that the
palate was furnished with teeth.
Fig. I5i.-Staiuof Bhyncho^auru* arti- The group of the Crocodiles

and Alligators (Crocodilia},

distinguished by the fact that the teeth are implanted in dis-
tinct sockets and the skin more or less extensively provided
with bony plates, is represented in the Triassic rocks by the
Stagonolepis of the Elgin Sandstones. The so-called " Theco-
dont" reptiles (such as Belodon, Thecodontosaurus, and Palao-
saurus, fig 152, c, d, e) are also nearly related to the Croco-
diles, though it is doubtful if they should be absolutely referred
to this group. In these reptiles, the teeth .are implanted in
distinct sockets in the jaws, their crowns being more or less
compressed and pointed, "with trenchant and finely serrate
margins" (Owen). The bodies of the vertebrae are hollowed

THE TRIASSIC PERIOD.

225

out at both ends, but the limbs appear to be adapted for pro-
gression on the land. The genus Belodon (fig. 152, c) is
known to occur in the Keuper of Germany and in America;
and Palaosaurus (fig. 153, e) has also been found in the Trias
of the same region. Teeth of the latter, however, are found,
along with remains of Thecodontosaurus (fig. 153, d), in a
singular magnesian conglomerate near Bristol, which was
originally believed to be of Permian age, but which appears
to be undoubtedly Triassic.

The Trias has also yielded the remains of the great marine
reptiles which are often spoken of collectively as the " Enalio-
saurians " or " Sea-lizards, " and which will be more particularly
spoken of in treating of the Jurassic period, of which they are
more especially characteristic. In all these reptiles the limbs
are flattened out, the digits being enclosed in a continuous
skin, thus forming powerful swimming-paddles, resembling the
" flippers " of the Whales and Dolphins both in their general
structure and in function. The tail is also long, and adapted
to act as a swimming-organ ; and there can be no doubt but
that these extraordinary and often colossal reptiles frequented
the sea, and only occasionally came to the land. The Triassic
Enaliosaurs belong to a group of which the later genus
Plesiosaurus is the type (the Sauropterygia}. One of the best
known of the Triassic genera is Nothosaurus (fig. 152, a), in
which the neck was long and bird-like, the jaws being im-

Fig. 152.— Triassic Reptiles, a. Skull of Nothosaurus mirabttis, reduced in size—
Muschelkalk, Germany ; b, Tooth of Simomurus Gaillardoti, of the natural size—
Muschelkalk, Germany ; c. Tooth of Belodon Carohnensis—Trlas, America ; d, Tooth
of Thecodontotaurua antiquus, slightly enlarged— Britain ; e, Tooth of Palceo»auru»
platyodon, of the natural size — Britain.

mensely elongated, and carrying numerous powerful conical
teeth implanted in distinct sockets. The teeth in Simosaurus
15

226 HISTORICAL PALAEONTOLOGY.

(152, b) are of a similar nature; but the orbits are of enormous
size, indicating eyes of corresponding dimensions, and perhaps
pointing to the nocturnal habits of the animal. In the singular
Placodus, again, the teeth are in distinct sockets, but resemble
those of many fishes in being rounded and obtuse (fig. 153),

forming broad crushing plates
adapted for the comminu-
tion of shell-fish. There is a
row of these teeth all round
the upper jaw proper, and a
double series on the palate,
but the lower jaw has only a
single row of teeth. Placodus
is found in the Muschelkalk,
and the characters of its den-
tal apparatus indicate that

Fig. 153.-Under surface of the upper !t was much more Peaceful
jaw and palate of Piacodua gigaa. Mus- in its habits than its asso-
cholkalk, Germany. . . ,, . j c"

ciates the Nothosaur and Si-

mosaur.

The Triassic rocks of South Africa and India have yielded
the remains of some extraordinary Reptiles, which have been
placed by Professor Owen in a separate order under the name
of Anomodontia. The two principal genera of this group are
Dicynodon and Oudenodon, both of which appear to have been
large Reptiles, with well-developed limbs, organized for pro-
gression upon the dry land. In Oudenodon (fig. 154, B) the
jaws seem to have been wholly destitute of teeth, and must
have been encased in a horny sheath, similar to that with
which we are familiar in the beak of a Turtle. In Dicynodon
(fig. 154, A), on the other hand, the front of the upper jaw
and the whole of the lower jaw were destitute of teeth, and
the front of the mouth must have constituted a kind of beak;
but the upper jaw possessed on each side a single huge conical
tusk, which is directed downwards, and must have continued
to grow during the life of the animal.

It may be mentioned that the above-mentioned Triassic
sandstones of South Africa have recently yielded to the re-
searches of Professor Owen a new and unexpected type of
Reptile, which exhibits some of the structural peculiarities
which we have been accustomed to regard as characteristic
of the Carnivorous quadrupeds. The Reptile in question has
been named Cynodraco, and it is looked upon by its distin-

THE TRIASSIC PERIOD.

227

guished discoverer as the type of a new order, to which he has
given the name of Theriodontia. The teeth of this singular
form agree with those of the Carnivorous quadrupeds in con-
sisting of three distinct groups — namely, front teeth or incisors,
eye teeth or canines, and back teeth or molars. The canines
also are long and pointed, very much compressed, and having
their lateral margins finely serrated, thus presenting a singular
resemblance to the teeth of the extinct " Sabre-toothed Tiger "
(Machairodus} . The bone of the upper arm (humerus) further
shows some remarkable resemblances to the same bone in the
Carnivorous Mammals. As has been previously noticed, Pro-
fessor Owen is of opinion that some of the Reptilian remains

Fig. 154.— Tr lassie Anoinodont Keptiles. A, Skull of Dieynodon lacerticeps. showing
one of the great maxillary tusks ; B, Skull of Oudenodon Bainii, showing the toothless,
beak- like jaws. From the Trias of South Africa. (After Owen.)

of the Permian deposits 'will also be found to belong to this
group of the " Theriodonts. "

Lastly, we find in the Triassic rocks the remains of Reptiles
belonging to the great Mesozoic order of the Deinosauria.
This order attains its maximum at a later period, and will be
spoken of when the Jurassic and Cretaceous deposits come to
be considered. The chief interest of the Triassic Reptiles of
this group arises from the fact that they are known by their

228 HISTORICAL PALEONTOLOGY.

footprints as well as by their bones; and a question has arisen
whether the supposed footprints of birds which occur in the
Trias have not really been produced by Deinosaurs. This
leads us, therefore, to speak at the same time as to the evi-
dence which we have of the existence of the class of Birds
during the Triassic period. No actual bones of any bird have
as yet been detected in any Triassic deposit ; but we have
tolerably clear evidence of their existence at this time in 'he
form of footprints. The impressions in question are found in
considerable numbers in certain red Sandstones of the age of
the Trias in the valley of the Connecticut River, in the United
States. They vary much in size, and have evidently been
produced by many different animals walking over long
stretches of estuarine mud and sand exposed at low water.
The footprints now under consideration form a double series
of single prints, and therefore, beyond all question, are the
tracks of a biped — that is, of an animal which walked upon

Fig. 155.— Supposed footprint of a Bird, from the Triassic Sandstones of the Con-
necticut River. The slab shows also numerous "rain- prints."

two legs. No living animals, save Man and the Birds, walk
habitually on two legs ; and there is, therefore, a prima facie
presumption that the authors of these prints were Birds.
Moreover, each impression consists of the marks of three toes
turned forward (fig. 155), and therefore are precisely such as
might be produced by Wading or Cursorial Birds. Further,
the impressions of the toes show exactly the same numerical

THE TRIASSIC PERIOD.

229

progression in the number of the joints as is observable in
living Birds — that is to say, the innermost of the three toes con-
sists of three joints, the middle one of four, and the outer
one of five joints. Taking this evidence collectively, it would
have seemed, until lately, quite certain that these tracks could
only have been formed by Birds. It has, however, been
shown that the Deinosaurian Reptiles possess, in some cases
at any rate, some singularly bird-like characters, amongst
which is the fact that the animal possessed the power of
walking, temporarily at least, on its hind-legs, which were
much longer and stronger than the fore-limbs, and which
were sometimes furnished with no more than three toes.
As the bones and teeth of Deinosaurs have been found in
the Triassic deposits of North America, it may be regarded as
certain that some of the bipedal tracks originally ascribed to
Birds must have really been produced by these Reptiles. It
seems at the same time almost a certainty that others of the
three-toed impressions of the Connecticut sandstones were in
truth produced by Birds, since it is doubtful if the bipedal
mode of progression was more than an occasional thing
amongst the Deinosaurs, and the greater number of the
many known tracks exhibit no impressions of fore-feet.
Upon the whole, therefore, we may, with much probability,
conclude that the great class of Birds (Aves} was in existence
in the Triassic period. If this be so, not only must there
have been quite a number of different forms, but some of
them must have been of very large size. Thus the largest

Fig. 156.— Lower jaw of Dromatherium sylvestre,
Trias, North Carolina. (After Emmons.)

a

Fig. 157.— a, Molar tooth of
Microleates antiquus, magni-
fied ; 6, Crown of the same,
magnified still further. Trias,
Germany.

footprints hitherto discovered in the Connecticut sandstones
are 22 inches long and 12 inches wide, \?ith a proportionate
length of stride. These measurements indicate a foot four
times as large as that of the African Ostrich; and the animal
which produced them — whether a Bird or a Deinosaur — must
have been of colossal dimensions.

230

HISTORICAL PALAEONTOLOGY.

Finally, the Trias completes the tale of the great classes of
the Vertebrate sub-kingdom by presenting us with remains of
the first known of the true Quadrupeds or Mammalia. These
are at present only known by their teeth, or, in one instance,
by one of the halves of the lower jaw; and these indicate
minute Quadrupeds, which present greater affinities with the

Fig. 158.— The Banded Ant-eater (MyrmecoMiis fasciatua) of Australia.

little Banded Ant-eater (Myrmecobius fasciatus, fig. 158) of
Australia than with any other living form. If this conjecture
be correct, these ancient Mammals belonged to the order of
the Marsupials or Pouched Quadrupeds (Marsupialia}, which
are now exclusively confined to the Australian province, South
America, and the southern portion of North America. In
the Old World, the only known Triassic Mammals belong to
the genus Microlestes, and to the probably identical Hypsi-
prymnopsis of Professor Boyd Dawkins. The teeth of Micro-
lestes (fig. 157) were originally discovered by Plieninger in
1847 in the " bone-bed " which is characteristic of the sum-
mit of the Rhaetic series both in Britain and on the continent
of Europe; and the known remains indicate two species. In
Britain, teeth of Microlestes have been discovered by Mr.
Charles Moore in deposits of Upper Triassic age, filling a
fissure in the Carboniferous limestone near Frome, in Somerset-
shire; and a molar tooth of Hypsiprymnopsis was found by
Professor Boyd Dawkins in Rhaetic marls below the "bone-
bed, " at Watchet, also in Somersetshire. In North America,

THE TRIASSIC PERIOD. 231

lastly, there has been found in strata of Triassic age one of
the branches of the lower jaw of a small Mammal, which has
been described under the name of Dromatherium sylvestre
(fig. 156). The fossil exhibits ten small molars placed side
by side, one canine, and three incisors, separated by small
intervals, and it indicates a small insectivorous animal, prob-
ably most nearly related to the existing Myrmecobius.

LITERATURE.

The following list comprises a few of the more important
sources of information as to the Triassic strata and their fossil
contents : —

(1) 'Geology of Oxford and the Valley of the Thames.'

Phillips.

(2) ' Memoirs of the Geological Survey of Great Britain and

Ireland. '

(3) ' Report on the Geology of Londonderry, ' &c. Portlock.

(4) " On the Zone of Avicula contorta, " &c. — ' Quart. Journ.

Geol. Soc., ' vol. xvi., 1860. Dr. Thomas Wright.

(5) " On the Zones of the Lower Lias and the Avicula con-

torta Zone " — ' Quart. Journ. Geol. Soc., ' vol. xvii., 1861.
Charles Moore.

(6) " On Abnormal Conditions of Secondary Deposits, " &c.

— ' Quart. Journ. Geol. Soc., ' vol. xxiii., 1876-77. Charles
Moore.

(7) ' Geognostische Beschreibung des Bayerischen Alpenge-

birges. ' Giimbel.

(8) 'Lethaea Rossica. ' Pander.

(9) ' Lethaea Geognostica. ' Bronn.

(10) ' Petrefacta Germaniae. ' Goldfuss.
(n) ' Petrefaktenkunde. ' Quenstedt.

(12) 'Monograph of the Fossil Estheriae' ( Palaeontographical

Society). Rupert Jones.

(13) "Fossil Remains of Three Distinct Saurian Animals,

recently discovered in the Magnesian Conglomerate
near Bristol "- -' Trans. Geol. Soc., ' ser. 2, vol. v., 1840.
Riley and Stutchbury.

(14) 'Die Saurier des Muschelkalkes. ' Von Meyer.

(15) ' Beitrage zur Palasontologie Wiirttembergs. ' Von

Meyer and Plieninger.

(16) 'Manual of Palaeontology.' Owen.

(17) ' Odontography. ' Owen.

(18) 'Report of Fossil Reptiles' (British Association, 1841).

Owen.

232 HISTORICAL PALEONTOLOGY.

(19) "On Dicynodon" — 'Trans. Geol. Soc., ' vol. Hi., 1845.

Owen.

(20) ' Descriptive Catalogue of Fossil Reptilia and Fishes in
the Museum of the Royal College of Surgeons, Eng-
land. ' Owen.

(21 ) " On Species of Labyrinthodon from Warwickshire " —

'Trans. Geol. Soc., ' ser. 2, vol. vi. Owen.

(22) "On a Carnivorous Reptile" (Cynodraco major), &c. —

' Quart. Journ. Geol. Soc., ' vol. xxxii., 1876. Owen.

(23) "On Evidences of Theriodonts in Permian Deposits,"
&c. — ' Quart. Journ. Geol Soc., ' vol. xxxii., 1876. Owen.

(24) " On the Stagonolepis Robertsoni, " &c. — ' Quart. Journ.

Geol. Soc., ' vol. xv., 1859. Huxley.

(25) "On a New Specimen of Telerpeton Elginense " —

'Quart. Journ. Geol. Soc., ' vol. xxiii., 1866. Huxley.

(26) " On Hyperodapedon " — ' Quart. Journ. Geol. Soc., ' vol.
xxv., 1869. Huxley.

(27) " On the Affinities between the Deinosaurian Reptiles

and Birds " — ' Quart. Journ. Geol. Soc., ' vol xxvi., 1870.
Huxley.

(28) " On the Classification of the Deinosauria. " &c. —

* Quart. Journ. Geol. Soc., ' vol. xxvi., 1870. Huxley.

(29) " Patoeontologica Indica " — ' Memoirs of the Geol. Sur-

vey of India. '

(30) " On the Geological Position and Geographical Distribu-
tion of the Dolomitic Conglomerate of the Bristol Area "
— ' Quart. Journ. Geol. Soc., ' vol. xxvi., 1870. R. Ethe-
ridge, sen.

(31) "Remains of Labyrinthodonta from the Keuper Sand-

stone of Warwick " — ' Quart. Journ. Geol. Soc., ' vol.
xxx., 1874. Miall.

(32) ' Manual of Geology. ' Dana.

(33) ' Synopsis of Extinct Batrachia and Reptilia of North

America. ' Cope.

(34) ' Fossil Footmarks. ' Hitchcock.

(35) ' Ichnology of New England.' Hitchcock.

(36) ' Traite de Paleontologie Vegetale. ' Schimper.

(37) ' Histoire des Vegetaux Fossiles. ' Brongniart.

(38) ' Monographic der Fossilen Coniferen. ' Goeppert.

CHAPTER XVI.

THE JURASSIC PERIOD.

Resting upon the Trias, with perfect conformity, and with
an almost undeterminable junction, we have the great series of

THE JURASSIC PERIOD. 233

deposits which are known as the Oolitic Rocks, from the com-
mon occurrence in them of oolitic limestones, or as the Juras-
sic Rocks, from their being largely developed in the mountain-
range of the Jura, on the western borders of Switzerland.
Sediments of this series occupy extensive areas in Great Britain,
on the continent of Europe, and in India. In North America,
limestones and marls of this age have been detected in " the
Black Hills, the Laramie range, and other eastern ridges of the
Rocky Mountains ; also over the Pacific slope, in the Uintah,
Wahsatch, and Humboldt Mountains, and in the Sierra Ne-
vada" (Dana); but in these regions their extent is still un-
known, and their precise subdivisions have not been deter-
mined. Strata belonging to the Jurassic period are also known
to occur in South America, in Austrafia, and in the Arctic
zone. When fully developed, the Jurassic series is capable of
subdivision into a number of minor groups, of which some are
clearly distinguished by their mineral characters, whilst others
are separated with equal certainty by the differences of the
fossils that they contain. It will be sufficient for our present
purpose, without entering into the more minute subdivisions
of the series, to give here a very brief and general account
of the main sub-groups of the Jurassic rocks, as developed in
Britain — the arrangement of the Jura-formation of the continent
of Europe agreeing in the main with that of England.

I. THE LIAS. — The base of the Jurassic series of Britain
is formed by the great calcareo-argillaceous deposit of the
" Lias, " which usually rests conformably and almost inseparably
upon the Rhaetic beds (the so-called "White Lias"), and
passes up, generally conformably, into the calcareous sand-
stones of the Inferior Oolite. The Lias is divisible into the
three principal groups of the Lower, Middle, and Upper Lias,
as below, and these in turn contain many well-marked " zones ; "
so that the Lias has some claims to be considered as an inde-
pendent formation, equivalent to all the remaining Oolitic
rocks. The Lower Lias (Terrain Sinemurien of D'Orbigny)
sometimes attains a thickness of as much as 600 feet, and con-
sists of a great series of bluish or greyish laminated clays,
alternating with thin bands of blue or grey limestone — the
whole, when seen in quarries or cliffs from a little distance,
assuming a characteristically striped and banded appearance.
By means of particular species of Ammonites, taken along with
other fossils which are confined to particular zones, the Lower
Lias may be subdivided into several well-marked horizons.

234 HISTORICAL PALEONTOLOGY.

The Middle Lias, or Marlstone Series (Terrain Liasien of
D'Orbigny), may reach a thickness of 200 feet, and consists of
sands, arenaceous marls, and argillaceous limestones, sometimes
with ferruginous beds. The Upper Lias (Terrain Toarcien of
D'Orbigny) attains a thickness of 300 feet, and consists princi-
pally of shales below, passing upwards into arenaceous strata.

II. THE LOWER OOLITES.— Above the Lias comes a com-
plex series of partly arenaceous and argillaceous, but prin-
cipally calcareous strata, of which the following are the more
important groups: a, the Inferior Oolite (Terrain Bajocien
of D'Orbigny), consisting of more than 200 feet of oolitic
limestones, sometimes more or less sandy; b, The Fuller's
Earth, a series of shales, clays, and marls, about 120 feet in
thickness; c, The Great Oolite or Bath Oolite (Terrain Bath-
onien of D'Orbigny), consisting principally of oolitic lime-
stones, and attaining a thickness of about 130 feet. The well-
known " Stonesfield Slates " belong to this horizon ; and the
locally developed " Bradford Clay, " " Cornbrash, " and " For-
est-marble " may be regarded as constituting the summit of
this group.

III. THE MIDDLE OOLITES. — The central portion of the
Jurassic series of Britain is formed by great argillaceous de-
posit, capped by calcareous strata, as follows : a, The Oxford
Clay (Terrain Callovien and Terrain Oxjordien of D'Orbigny),
consisting of dark-colored laminated clays, sometimes reach-
ing a thickness of 700 feet, and in places having its lower por-
tion developed into a hard calcareous sandstone ("Kelloway
Rock"); b, The Coral-Rag (Terrain Corallien of D'Orbigny,
" Nerinean Limestone " of the Jura, " Diceras Limestone " of
the Alps), consisting, when typically developed, of a central
mass of oolitic limestone, underlaid and surmounted by cal-
careous grits.

IV. THE UPPER OOLITES. — a, The base of the Upper
Oolites of Britain is constituted by a great thickness (600 feet
or more) of laminated, sometimes carbonaceous or bituminous
clays, which are known as the Kimmeridge Clay (Terrain Kim-
meridgien of D'Orbigny) ; b, The Portland Beds (Terrain Port-
landien of D'Orbigny) succeed the Kimmeridge clay, and con-
sist inferiorly of sandy beds surmounted by oolitic limestones
("Portland Stone"), the whole series attaining a thickness of
150 feet or more, and containing marine fossils; c, The Pur-
beck Beds are apparently peculiar to Great Britain, where they
form the summit of the entire Oolitic series, attaining a total

THE JURASSIC PERIOD. 235

thickness of from 150 to 200 feet. The Purbeck beds consist
of arenaceous, argillaceous, and calcareous strata, which can
be shown by their fossils to consist of a most remarkable alter-
nation of fresh-water, brackish-water, and purely marine sedi-
ments, together with old land-surfaces, or vegetable soils, which
contain the upright stems of trees, and are locally known as
" Dirt-beds. "

One of the most important of the Jurassic deposits of the
continent of Europe, which is believed to be on the horizon
of the Coral-rag or of the lower part of the Upper Oolites, is
the " Solenhofeu Slate " of Bavaria, an exceedingly fine-grained
limestone, which is largely used in lithography, and is cele-
brated for the number and beauty of its organic remains, and
especially for those of Vertebrate animals.

The subjoined sketch-section (fig. 159) exhibits in a dia-
grammatic form the general succession of the Jurassic rocks of
Britain.

Regarded as a whole, the Jurassic formation is essentially
marine ; and though remains of drifted plants, and of insects
and other air-breathing animals, are not uncommon, the fossils
of the formation are in the main marine. In the Purbeck
series of Britain, anticipatory of the great .river-deppsit of the
Wealden, there are fresh-water, brackish-water, and even terres-
trial strata, indicating that the floor of the oolitic ocean was
undergoing upheaval, and that the marine conditions which
had formerly prevailed were nearly at an end. In places
also, as in Yorkshire and Sutherlandshire, are found actual
beds of coal : but the great bulk of the formation is an indu-
bitable sea-deposit; and its limestones, oolitic as they com-
monly are, nevertheless are composed largely of the commin-
uted skeletons of marine animals. Owing to the enormous
number and variety of the organic remains which have been
yielded by the richly fossiliferous strata of the Oolitic series,
it will not be possible here to do more than to give an outline-
sketch of the principal forms of life which characterize the
Jurassic period as a whole. It is to be remembered, however,
that every minor group of the Jurassic formation has its own
peculiar fossils, and that by the labors of such eminent ob-
servers as Quenstedt, Oppel, D'Orbigny, Wright, De la Beche,
Tate, and others, the entire series of Jurassic sediments admits
of a more complete and more elaborate subdivision into zones
characterized by special life-forms than has as yet been found
practicable in the case of any other rock-series.

HISTORICAL PALAEONTOLOGY.

GENERALIZED SECTION OF THE JURASSIC ROCKS
OF ENGLAND.

Fig. 159-

— Purbeck Beds.
—- Portland Beds.

Kimmeridge Clay.

Coral -Rag.

Oxford Clay.

5 Cornbrash and Forest-
l marble.
Great Oolite.

Fuller's Earth.
Inferior Oolite.

Upper Lias.

Middle Lias (Marl-
stone series).

Lower Lias.

J Rhsetic Marls (" White
I Lias").

The plants of the Jurassic period consist principally of
Ferns, Cycads, and Conifers — agreeing in this respect, there-
fore, with those of the preceding Triassic formation. The
Ferns are very abundant, and belong partly to old and partly
to new genera. The Cycads are also very abundant, and, on

THE JURASSIC PERIOD. 237

/

the whole, constitute the most marked feature of the Jurassic
vegetation, many genera of this group being known (Ptero-
phyllum, Otozamites, Zamites, Crossozamia, Williamsonia, Buck-
landia, &c.) The so-called "dirt-bed" of the Purbeck series
consists of an ancient soil, in which stand erect the trunks of
Conifers and the silicified stools of Cycads of the genus Mantel-
lia (fig. 160). The Co-nifera of the Jurassic are represented by
various forms more or less nearly allied to the existing Arau-
carice; and these are known not only by their stems or
branches, but also in some cases by their cones. We meet,
also, with the remains of undoubted Endogenous plants, the
most important of which are the fruits of forms allied to the
existing Screw-pines (Pandanece}, such as Podocarya and Kaida-
carpum. So far, however, no remains of Palms have been
found; nor are we acquainted with any Jurassic plants which
could be certainly referred to the great " Angiospermous "
group of the Exogens, including the majority of our ordinary
plants and trees.

Amongst animals, the Protozoans are well represented in
the Jurassic deposits by numerous Foraminifers and Sponges;
as are the Coclenterates by numerous Corals, Remains

Fig. 160.— Mantellia (Cycadeoidea) megalophylla, a Cycad from the Purbeck
"dirt-bed." Upper Oolites, England.

of these last-mentioned organisms are extremely abundant
in some of the limestones of the formation, such as the
" Coral-rag " and the Great Oolite ; and the former of these
may fairly be considered as an ancient " reef. " The Rugose
Corals have not hitherto been detected in the Jurassic rocks;
and the " Tabulate Corals, " so-called, are represented only by
examples of the modern genus Millepora. With this excep-
tion, all the Jurassic Corals belonging to the great group which
predominates in recent seas (Zoantharia sclerodermata) ; and

238 HISTORICAL PALAEONTOLOGY.

the majority belong to the important reef -building family of
the "Star-corals" (Astrccida) . The form here figured (Thecos-
milia annularis, fig. 161) is one of the characteristic species
of the Coral-rag.

The Echinoderms are very numerous and abundant fossils
in the Jurassic series, and are represented by Sea-lilies, Sea-
urchins, Star-fishes, and Brittle-stars. The Crinoids are still
common, and some of the limestones of the series are largely
composed of the debris of these organisms. Most of the
Jurassic forms resemble those with which we are already
familiar, in having the body permanently attached to some
foreign object by means of a longer or shorter jointed stalk

Fig. 161. — Tkecosmilia annularis. Coral-rag, England.

or " column. " One of the most characteristic Jurassic genera
of these " stalked " Crinoids (though not exclusively confined
io this period) is Pentacrinus (fig. 162). In this genus, the
column is five-sided, with whorls of " side-arms ; " and the arms
are long, slender, and branched. The genus is represented
at the present day by the beautiful " Medusa-head Pentacrin-
ite" (Pentacrinus caput-medusa). Another characteristic Oolitic
genus is Apiocrinus, comprising the so-called " Pear Encrinites. "
In this group the column is long and rounded, with a dilated
base, and having its uppermost joints expanded so as to form,
with the cup itself, a pear-shaped mass, from the summit of
which spring the comparatively short arms. Besides the

THE JURASSIC PERIOD. 239

" stalked " Crinoids, the Jurassic rocks have yielded the re-
mains of the higher group of the " free " Crinoids, such as

Fig. 162.— Pentacrinusfaaciculoaw, Lias. The left-hand figure shows a few of the
joints of the column ; the middle figure shows the arms, and the summit of the column
with its side-arms ; and the right-hand figure shows the articulating surface of one of
the column-joints.

Saccosoma. These forms resemble the existing " Feather-
stars" (Comatula) in being attached when young to some

240 HISTORICAL PALAEONTOLOGY.

foreign body by means of a jointed stem, from which they
detach themselves when fully grown to lead an independent
existence. In this later stage of their life, therefore, they
closely resemble the Brittle-stars in appearance. True Star-
fishes (Asteroids) and Brittle-stars (Ophiuroids) are abundant
in the Jurassic rocks, and the Sea-urchins (Echinoids) are so
numerous and so well preserved as to constitute quite a marked
feature of some beds of the series. All the Oolitic urchins
agree with the modern Echinoids in having the shell composed
of no more than twenty rows of plates. Many different genera
are known, and a characteristic species of the Middle Oolites
(Hemicidaris crenularis, fig. 163) is here figured.

Fig. Wd.—Hemicidaria crenularis, showing the great tubercles on which the
spines were supported. Middle Oolites.

Passing over the Annelides, which, though not uncommon,
are of little special interest, we come to the Articulates, which
also require little notice. Amongst the Crustaceans, whilst the
little Water-fleas (Ostracoda) are still abundant, the most
marked feature is the predominance which is now assumed by the
Decapods — the highest of the known groups of the class. True
Crabs (Brachyura) are by no means unknown; but the prin-
cipal Oolitic Decapods belonged to the " Long-tailed " group
(Macrura), of which the existing Lobsters, Prawns, and
Shrimps are members. The fine-grained lithographic slates of
Solenhofen are especially famous as a depot for the remains
of these Crustaceans, and a characteristic species from this
locality (Eryon arctiformis, fig. 164) is here represented.
Amongst the air-breathing Articulates, we meet in the Oolitic
rocks with the remains of Spiders (Arachnids), Centipedes
(Myriapoda), and numerous true Insects (Insecta), In con-
nection with the last-mentioned of these groups, it is of interest

THE JURASSIC PERIOD.

241

to note the occurrence of the oldest known fossil Butterfly
— the Palceontina Oolitica of the Stonesfield slate — the rela-
tionships of which appear to be with some of the living
Butterflies of Tropical America.

Coming to the Mollusca, the Polyzoans, numerous and

Fig. 164.— Eryon arctifonuis, a " Long-tailed Decapod," from the Middle
Oolites (Solenhof en Slate.)

beautiful as they are, must be at once dismissed; but the
Brachiopods deserve a moment's attention. The Jurassic
Lamp-shells (fig. 165) do not fill by any means such a pre-
dominant place in the marine fauna of the period, as in many
Palaeozoic deposits, but they are still individually numerous.
The two ancient genera Left tana (fig. 165, a) and Spirifera (fig.
165, fc), dating the one from the Lower and the other from the
Upper Silurian, appear here for the last time upon the scene,
but they have not hitherto been recognized in deposits later
than the Lias. The great majority of the Jurassic Brachiopods,
however, belong to the genera Terebratula (fig. 165 c, e, /)
and Rhynchonella (fig. 165, d}, both of which are represented
by living forms at the present day. The Terebratula, in par-
16

242

HISTORICAL PALEONTOLOGY.

ticular, are very abundant, and the species are often confined
to special horizons in the series.

Remains of Bivalves (Lamcllibranchiata} are very numerous
in the Jurassic deposits, and in many cases highly character-
istic. In the marine beds of the Oolites, which constitute by
far the greater portion of the whole formation, the Bivalves
are of course marine, and belong to such genera as Trigonia,
Lima, Pholadomya, Cardinia, Avicula, Hippo podium, &c. ; but
in the Purbeck beds, at the summit of the series, we find
bands of Oysters alternating with strata containing fresh-water
or brackish-water Bivalves, such as Cyrcncc and Corbula. The
predominant Bivalves of the Jurassic, however, are the Oysters,

Fig. 165. — Jurassic Brachiopods. «, Lept&na Liasaica, enlarged, the small cross be-
low the figure indicating the true size of the shell— Lias, b, Spirifera rostrata, Lias ; c,
Terebratula quadrifida, Lias ; d, d', Rhynchonella varians, Fuller's Earth and Kello-
way Rock ; e. Terebratula spficeroidalis, Inferior Oolite ; /, Terebratula dlgona, Brad-
ford Clay, Forest- marble, and Great Oolite. (After Davidson).

which occur under many forms, and often in vast numbers,
particular species being commonly restricted to particular
horizons. Thus of the true Oysters, Ostrea distorta is char-
acteristic of the Purbeck series, where it forms a bed twelve
feet in thickness, known locally as the " Cinder-bed ; " Ostrea
expansa abounds in the Portland beds; Ostrea deltoidea is
characteristic of the Kimmeridge clay ; Ostrea gregaria pre-
dominates in the Coral-rag; Ostrea acuminata characterizes the
small group of the Fuller's Earth; whilst the plaited Ostrea

THE JURASSIC PERIOD.

243

Marshii (fig. 166) is a common shell in the Lower and Middle
Oolites. Besides the more typical Oysters, the Oolitic rocks
abound in examples of the singularly unsymmetrical forms
belonging to the genera Exogyra and Gryphaa (fig. 167). In
the former of these are included Oysters with the beaks
" reversed " — that is to say, turned towards the hinder part of
the shell; whilst in the latter are Oysters in which the lower
valve of the shell is much the largest, and has a large incurved
beak, whilst the upper valve is small and concave. One of
the most characteristic Exogyra is the E. Virgula of the Oxford
Clay, and of the same horizon on the Continent; and the
Gryphaa incurva (fig. 167) is equally abundant in, and char-
acteristic of, the formation of the Lias. Lastly, we may

Fig. 166.— Ostrea Marshii. Middle
and Lower Oolites.

Fig. 167. — Gryphcea incurva. Lias.

notice the extraordinary shells belonging to the genus Diceras
(fig. 168), which are exclusively confined to the Middle

Oolites. In this formation in
the Alps they occur in such
abundance as to give rise to
the name of " Calcaire a Di-
cerates, " applied to beds of
the same age as the Coral-
rag of Britain. The genus Di-
ceras belongs to the same fam-
ily as the " Thorny Clams "
(Chama) of the present day —
the shell being composed of

nearly equally-sized valves, the
Fig. m.-Dicera^arietina. Middle beakg Qf whkh arg extremely

prominent and twisted into a

spiral. The shell was attached to some foreign body by the
l:eak of one of its valves.

244

HISTORICAL PALEONTOLOGY.

Amongst the Jurassic Univalves (Gasteropoda) there are
many examples of the ancient and long-lived Pleurotomaria;
but on the whole the Univalves begin to have a modern
aspect. The round-mouthed (" holostomatous "), vegetable-
eating Sea-snails, such as the Limpets (Patellidcc), the Nerites
(Nerita), the Turritellcu, Chemnitzice, &c., still hold a predomi-
nant place. The two most noticeable genera of this group
are Cerithium and Ner'maa — the former of these attaining
great importance in the Tertiary and Recent seas, whilst the
latter (fig. 169) is highly characteristic of the Jurassic series,
though not exclusively confined to
it. One of the limestones of the
Jura, believed to be of the age of
the Coral-rag (Middle Oolite) of Bri-
tain, abounds to such an extent in
the turreted shells of Nerincea as to
have gained the name of " Calcaire
a Nerinees. " In addition to forms
such as the preceding, we now for
the first time meet, in any force,
with the Carnivorous -Univalves, in
which the mouth of the shell is
notched or produced into a canal,
giving rise to the technical name Fig. IGO. — Nerincea Goodhaiiu,

f « . , „ r , one-fourth of the natural size. The

SlpnonostomatOUS, applied to left-hand figure shows the appear-

the shell. Some of the carnivorous
forms belong to extinct types, such land,
as the Purpuroidea of the Great Oo-
lite; but others are referable to well-known existing genera.
Thus we meet here with species of the familiar groups of the
Whelks (Buccinum), the Spindle-shells (Fusus), the Spider-
shells (Pteroceras), Murex, Rostellaria, and others which are
not at present known to occur in any earlier formation.

Amongst the Wing-shells (Pteropoda),it is sufficient to mark
the final appearance in the Lias of the ancient genus Conularia.

Lastly, the order of the Cephalopoda, in both its Tetrabran-
chiate and Dibranchiate sections, undergoes a vast devel-
opment in the Jurassic period. The old and comparatively
simple genus Nautilus is still well represented, one species
being very similar to the living Pearly Nautilus (N. pompilius) ;
but the Orthocerata and Goniatites of the Trias have finally
disappeared; and the great majority of the Tetrabranchiate
forms are referable to the comprehensive genus Ammonites,

THE JURASSIC PERIOD.

245

with its many sub-genera and its hundreds of recorded species.
The shell in Ammonites is in the form of a flat spiral, all the
coils of which are in contact (figs. 170 and 171). The inner-

Fig, no.— Ammonites Humphrcaianus . Inferior Oolite.

most whorls of the shell are more or less concealed ; and the
body-chamber is elongated and narrow, rather than expanded
towards the mouth. The tube or siphuncle which runs through
the air-chambers is placed on the dorsal or convex side of the

Fig. 171.— Ammonites bifrons. Lias.

shell ; but the principal character which distinguishes Ammon-
ites from Goniatites and Ceratites is the wonderfully complex
manner in which the septa, or partitions between the air-cham-
bers, are folded and undulated. To such' an extent does this

246 HISTORICAL PALEONTOLOGY.

take place, that the edges of the septa, when exposed by the
removal of the shell-substance, present in an exaggerated man-
ner the appearance exhibited by an elaborately-dressed shirt-
frill when viewed edgewise. The species of Ammonites range
from the Carboniferous to the Chalk; but they have not been
found in deposits older than the Secondary, in any region
except India; and they are therefore to be regarded as essen-
tially Mesozoic fossils. Within these limits, each formation
is characterized by particular species, the number of individ-
uals being often very great, and the size which is sometimes
attained being nothing short of gigantic. In the Lias, par-
ticular species of Ammonites may succeed one another regu-
larly, each having a more or less definite horizon, which it does
not transgress. It is thus possible to distinguish a certain
number of zones, each characterized by a particular Ammonite,
together with other associated fossils. Some of these zones
are very persistent and extend over very wide areas, thus af-
fording valuable aid to the geologist in his determination of
rocks. It is to be remembered, however, that there are other
species which are not thus restricted in their vertical range,
even in the same formations in which definite zones occur.

The Cuttle-fishes or Dibranchiate Cephalopods constitute a
feature in the life of the Jurassic period little less conspicuous
and striking than that afforded by the multitudinous and varied
chambered shells of the Ammonitidte. The remains by which
these animals are recognized are necessarily less perfect, as a
rule, than those of the latter, as no external shell is present
(except in rare and more modern groups), and the internal
skeleton is not necessarily calcareous. Nevertheless, we have
an ample record of the Cuttle-fishes of the Jurassic period, in
the shape of the fossilized jaws or beak, the ink-bag, and, most
commonly of all, the horny or calcareous structure which is
embedded in the soft tissues, and is variously known as the
" pen " or " bone. " The beaks of Cuttle-fishes, though not
abundant, are sufficiently plentiful to have earned for them-
selves the general title of " Rhyncholites ; " and in their form
and function they resemble the horny, parrot-like beak of the
existing Cephalopods. The ink-bag or leathery sac in which
the Cuttle-fishes store up the black pigment with which they
obscure the water when attacked, owes its preservation to the
fact that the coloring-matter which it contains is finely-divided
carbon, and therefore nearly indestructible except by heat.
Many of these ink-bags have been found in the Lias; and the

THE JURASSIC PERIOD.

247

coloring-matter is sometimes so well preserved that it has
been, as an experiment, employed in painting as a fossil
" sepia. " The " pens " of the Cuttle-fishes are not commonly
preserved, owing to their horny consistence, but they are not
unknown. The form here figured (Beloteuthis subcostata, fig.
172) belonged to an old type essentially similar to our modern
Calamaries, the skeleton of which consists of a horny shaft
and two lateral wings, somewhat like a feather in general
shape. When, on the other hand, the internal skeleton is
calcareous, then it is very easily preserved
in a fossil condition; and the abundance
of remains of this nature in the Secondary
rocks, combined with their apparent total
absence in Palaeozoic strata, is a strong pre-
sumption in favor of the view that the order
of the Cuttle-fishes did not come into exist-
ence till the commencement of the Meso-
zoic period. The great majority of the skele-
tons of this kind which are found in the Jur-
assic rocks belong to the great extinct family
of the "Belemnites" (Belemnitidce}, which, so
far as known, is entirely confined to rocks
of Secondary age. From its pointed, ' gener-
ally cylindro-conical form, the skeleton of
the Belemnite is popularly Known as a "thun-
derbolt" (fig. 173, C). In its perfect condition
— in which it is, however, rarely obtainable —
the skeleton consists of a chambered conical
shell (the " phragmacone "), the partitions between the chambers
of which are pierced by a marginal tube or " Siphuncle. " This
conical shell — curiously similar in its structure to the external
shell of the Nautilus — is extended forwards into a horny
"pen," and is sunk in a corresponding conical pit (fig. 173, B),
excavated in the substance of a nearly cylindrical fibrous
body or "guard," which projects backwards for a longer or
shorter distance, and is the part most usually found in a fossil
condition. Many different kinds of Belemnites are known, and
their guards literally swarm in many parts of the Jurassic series,
whilst some specimens attain very considerable dimensions.
Not only is the internal skeleton known, but specimens of
Belemnites and the nearly allied Belemnoteuthis have been found
in some of the fine-grained sediments of the Jurassic formation,
from which much has been learnt even as to the anatomy of

Fig. 172.— Beioteu-
Jur"

248

HISTORICAL PALAEONTOLOGY.

the soft parts of the animal. Thus we know that the Belem-
nites were in many respects comparable with the existing

Fig. 173.— A, Restoration of the animal of the Belemnite ; B, Diagram showing the
complete skeleton of a Belemnite, consisting of the chambered phragmacone (a;, the
guard (6), and the horny pen (c) ; C, Specimen of Belemnites canaliculatus, from the
Inferior Oolite. (After Phillips.)

Calamaries or Squids, the body being furnished with lateral
fins, and the head carrying a circle of ten " arms, " two of

Fig. Yl^.—Tetragonolepis (restored), and scales of the same. Lias.

which were longer than the others (fig. 173, A). The suckers
on the arms were provided, further, with horny hooks; there

THE JURASSIC PERIOD.

249

was a large ink-sac ; and the mouth was armed with horny
mandibles resembling in shape the beak of a parrot.

Coming next to the Vertebrates, we find that the Jurassic
Fishes are still represented by Ganoids and Placoids. The
Ganoids, however, unlike the old forms, now for the most
part possess nearly or quite symmetrical (" homocercal") tails.
A characteristic genus is Tetragonolepis (fig. 174), with its
deep, compressed body, its rhomboidal, closely-fitting scales,
and its single long dorsal fin. Amongst the Placoids the teeth
of true Sharks (Notidanus) occur for the first time; but by far
the greater number of remains referable to this group are still
the fin-spines and teeth of " Cestracionts, " resembling the
living Port-Jackson Shark. Some of these teeth are pointed
(Hybodus} ; but others are rounded, and are adapted for crush-
ing shell-fish. Of these latter, the commonest are the teeth of
Acrodus (fig. 175), of which the hinder ones are of an elon-
gated form, with a rounded
surface, covered with fine
transverse striae proceed-
ing from a central longi-
tudinal line. From their
general form and striation,
and their dark color, these
teeth are commonly called
" fossil leeches " by the quarrymen.

The Amphibian group of the Labyrinthodonts, which was so
extensively developed in the Trias, appears to have become
extinct, no representative of the order having hitherto been
detected in rocks of Jurassic age.

Much more important than the Fishes of the Jurassic series
are the Reptiles, which are both very numerous, and belong to
a great variety of types, some of these being very extraordinary

Fig. 175.— Tooth of Acrodut nobilis. Lias.

Fig. 176. — Ichthyosaurus communis. Lias.

in their anatomical structure. The predominant group is that
of the " Enaliosaurs " or " Sea-lizards, " divided into two great
orders, represented respectively by the Ichthyosaurus and the
Plesiosaurus.

250 HISTORICAL PALEONTOLOGY.

The Ichthyosauri or "Fish-Lizards" are exclusively Meso-
zoic in their distribution, ranging from the Lias to the Chalk,
but abounding especially in the former. They were huge
Reptiles, of a fish-like form, with a hardly conspicuous neck
(fig. 176), and probably possessing a simply smooth or
wrinkled skin, since no traces of scales or bony integumentary
plates have ever been discovered. The tail was long, and
was probably furnished at its extremity with a powerful ex-
pansion of the skin, constituting a tail-fin similar to that pos-
sessed by the Whales. The limbs are also like those of Whales
in the essentials of their structure, and in their being adapted
to act as swimming-paddles. Unlike the Whales, however,
the Ichthyosaurs possessed the hind-limbs as well as the fore-
limbs, both pairs having the bones flattened out and the fin-
gers completely enclosed in the skin, the arm and leg being at
the same time greatly shortened. The limbs are thus con-
verted into efficient "flippers," adapting the animal for an
active existence in the sea. The different joints of the back-
bone (vertebrae) also show the same adaptation to an aquatic
mode of life, being hollowed out at both ends, like the bicon-
cave vertebrae of Fishes. The spinal column in this way was
endowed with the flexibility necessary for an animal intended
to pass the greater part of its time in water. Though the Ich-
thyosaurs are undoubtedly marine animals, there is, however,
reason to believe that they occasionally came on shore, as they
possess a strong bony arch, supporting the fore-limbs, such as
would permit of partial, if laborious, terrestrial progression.
The head is of enormous size, with greatly prolonged jaws,
holding numerous powerful conical teeth lodged in a common
groove. The nature of the dental apparatus is such as to
leave no doubt as to the rapacious and predatory habits of the
Ichthyosaurs — an inference which is further borne out by the
examination of their petrified droppings, which are known to
geologists as " coprolites, " and which contain numerous frag-
ments of the bones and scales of the Ganoid fishes which
inhabited the same seas. The orbits are of huge size ; and as
the eyeball was protected, like that of birds, by a ring of bony
plates in its outer coat, we even know that the pupils of the
eyes were of correspondingly large dimensions. As these bony
plates have the function of protecting the eye from injury
under sudden changes of pressure in the surrounding medium,
it has been inferred, with great probability, that the Ichthy-
osaurs were in the habit of diving to considerable depths in

THE JURASSIC PERIOD.

251

the sea. Some of the larger specimens of Ichthyosaurus which
have been discovered in the Lias indicate an animal of from
20 to nearly 40 feet in length; and many species are known to
have existed, whilst fragmentary remains of their skeletons are
very abundant in some localities. We may therefore safely
conclude that these colossal Reptiles were amongst the most
formidable of the many tyrants of the Jurassic seas.

The Plesiosaurus (fig. 177) is another famous Oolitic
Reptile, and, like the preceding, must have lived mainly or
exclusively in the sea. It agrees with the Ichthyosaur in some
important features of its organization, especially in the fact
that both pairs of limbs are converted into " flippers " or
swimming-paddles, whilst the skin seems to have been equally
destitute of any scaly or bony investiture. Unlike the Ichthy-

Fig. in.—Plesiosauru8 dolicfiodeirua , restored. Lias.

osaur, however, the Plesiosaur had the paddles placed far back,
the tail being extremely short, and the neck greatly lengthened
out, and composed of from twenty to forty vertebrae. The
bodies of the vertebras, also, are not deeply biconcave, but are
flat, or only slightly cupped. The head is of relatively small
size, with smaller orbits than those of the Ichthyosaur, and with
a snout less elongated. The jaws, however, were armed with
numerous conical teeth, inserted in distinct sockets. As re-
gards the habits of the Plesiosaur, Dr. Conybeare arrives at the
following conclusions: "That it was aquatic is evident from
the form of its paddles; that it was marine is almost equally
so from the remains with which it is universally associated;

252 HISTORICAL PALEONTOLOGY.

that it may have occasionally visited the shore, the resem-
blance of its extremities to those of the Turtles may lead us to
conjecture: its movements, however, must have been very
awkward on land; and its long neck must have impeded its
progress through the water, presenting a strong contrast to the
organization which so admirably fits the Ichthyosaurus to cut
through the waves. " As its respiratory organs were such that
it must of necessity have required to obtain air frequently, we
may conclude "that it swam upon or near the surface, arching
back its long neck like a swan, and occasionally darting it
down at l!ie fish which happened to float within its reach. It
may perhaps have lurked in shoal water along the coast, con-
cealed amongst the sea-weed ; and raising its nostrils to a
level with the surface from a considerable depth, may have
found a secure retreat from the assaults of powerful enemies;
while the length and flexibility of its neck may have compen-
sated for the want of strength in its jaws, and its incapacity
for swift motion through the water. "

About twenty species of Plesiosaurus are known, ranging
from the Lias to the Chalk, and specimens have been found
indicating a length of from eighteen to twenty feet. The
nearly related " Pliosaurs," however, with their huge heads
and short necks, must have occasionally reached a length of at
least forty feet — the skull in some species being eight, and the
paddles six or seven feet long, whilst the teeth are a foot in
length.

Another extraordinary group of Jurassic Reptiles is that of
the " Winged Lizards " or Pterosauria. These are often spoken
of collectively as " Pterodactyles, " from Pterodactylus, the
type-genus of the group. As now restricted, however, the
genus Pterodactylus is more Cretaceous than Jurassic, and it is
associated in the Oolitic rocks with the closely allied genera
Dimorphodon and Rhamphorhynchus. In all three of these
genera we have the same general structural organization, in-
volving a marvellous combination of characters, which we are in
the habit of regarding as peculiar to Birds on the one hand, to
Reptiles on another hand, and to the Flying Mammals or
Bats in a third direction. The " Pterosaurs " are " Flying "
Reptiles, in the true sense of the term, since they were indu-
bitably possessed of the power of active locomotion in the air,
after the manner of Birds. The so-called "Flying" Reptiles
of the present day, such as the little Draco volans of the East
Indies and Indian Archipelago, possess, on the other hand, no

THE JURASSIC PERIOD. 253

power of genuine flight, being merely able to sustain themselves
in the air through the extensive leaps which they take from tree
to tree, the wing-like expansions of the skin simply exercising
the mechanical function of a parachute. The apparatus of flight
in the " Pterosaurs " is of the most remarkable character, and
most resembles the " wing " of a Bat, though very different in
some important particulars. The " wing " of the Pterosaurs is
like that of Bats, namely, in consisting of a thin leathery expan-
sion of the skin which is attached to the sides of the body, and
stretches between the fore and hind limbs, being mainly sup-
ported by an enormous elongation of certain of the digits of

Fig. I1%.—Pterodactylu8 crasslrostris. From the Lithographic Slates of Solenhofen
(Middle Oolite. ) The figure is " restored," and it seems certain that the restoration
is incorrect in the comparatively unimportant particular, that the hand should consist
of no more than four fingers, three short and one long, Instead of five, as represented.

the hand. In the Bats, it is the four outer fingers which are
thus lengthened out; but in the Pterosaurs, the wing-membrane
is borne by a single immensely-extended finger (fig. 178).
No trace of the actual wing-membrane itself has, of course,
been found fossilized ; but we could determine that the " Ptero-
dactyles " possessed the power of flight, quite apart from the ex-
traordinary conformation of the hand. The proofs of this are to
be found partly in the fact that the breast-bone was furnished
with an elevated ridge or keel, serving for the attachment of
the great muscles of flight, and still more in the fact that the

254 HISTORICAL PALEONTOLOGY.

bones were hollow and were filled with air — a peculiarity
wholly confined amongst living animals to Birds only. The
skull of the Pterosaurs is long, light, and singularly bird-like in
appearance — a resemblance which is further increased by the
comparative length of the neck and the size of the vertebrae of
this region (fig. 178). The jaws, however, unlike those of any
existing Bird, were, with one exception to be noticed hereafter,
furnished with conical teeth sunk in distinct sockets; and
there was always a longer or shorter tail composed of distinct
vertebrae ; whereas in all existing Birds the tail is abbreviated,
and the terminal vertebrae are amalgamated to form a single
bone, which generally supports the great feathers of the tail.

Modern naturalists have been pretty generally agreed that
the Pterosaurs should be regarded as a peculiar group of the
Reptiles; though they have been and are still regarded by
high authorities, like Professor Seeley, as being really referable
to the Birds, or as forming a class by themselves. The chief
points which separate them from Birds, as a class, are the
character of the apparatus of flight, the entirely different struc-
ture of the fore-limb, the absence of feathers, the composition
of the tail out of distinct vertebrae, and the general presence
of conical teeth sunk in distinct sockets in the jaws. The gap
between the Pterosaurs and the Birds has, however, been
greatly lessened of late by the discovery of fossil animals
(Ichthyornis and Hesperornis} with the skeleton proper to Birds
combined with the presence of teeth in the jaws, and by the
still more recent discovery of other fossil animals (Pteranodon)
with a Pterosaurian skeleton, but without teeth; whilst the un-
doubtedly feathered Archaopteryx possessed a long tail com-
posed of separate vertebras. Upon the whole, therefore, the
relationships of the Pterosaurs cannot be regarded as absolutely
settled. It seems certain, however, that they did not possess
feathers — this implying that they were cold-blooded animals;
and their affinities with Reptiles in this, as in other characters,
are too strong to be overlooked.

The Pterosaurs are wholly Mesozoic, ranging from the Lias
to the Chalk inclusive; and the fine-grained Lithographic Slate
of Solenhofen has proved to be singularly rich in their remains.
The genus Pterodactylus itself has the jaws toothed to the ex-
tremities with equal-sized conical teeth, and its species range
from the Middle Oolites to the Cretaceous series, in connec-
tion with which they will be again noticed, together with the
toothless genus Pteranodon. The genus Dimorphodon is Li-

THE JURASSIC PERIOD. 255

assic, and is characterized by having the front teeth long and
pointed, whilst the hinder teeth are small and lancet-shaped.
Lastly, the singular genus Rhamphorhynchus, also from the
Lower Oolites, is distinguished by the fact that there are teeth
present in the hinder portions of both jaws; but the front por-
tions are toothless, and may have constituted a horny beak.
Like most of the other Jurassic Pterosaurs, Rhamphorhynchus
(fig. 179) does not seem to have been much bigger than a
pigeon, in this respect falling far below the giant " Dragons "
of the Cretaceous period. It differed from its relatives, not

Fig. IVZ.—Rhamphorhynchua Bucklandi, restored. Bath Oolite, England.
(After the late Professor Phillips.)

only in the armature of the mouth, but also in the fact that
the tail was of considerable length. With regard to its habits
and mode of life, Professor Phillips remarks that, "gifted with
ample means of flight, able at least to perch on rocks and
scuffle along the shore, perhaps competent to dive, though not
so well as a Palmiped bird, many fishes must have yielded to
the cruel beak and sharp teeth of Rhamphorhynchus. If we
ask to which of the many families of Birds the analogy of
structure and probable way of life would lead us to assimilate
Rhamphorhynchus, the answer must point to the swimming
races with long wings, clawed feet, hooked beak, and habits of
violence and voracity; and for preference, the shortness of the
legs, and other circumstances, may be held to claim for the
Stonesfield fossil a more than fanciful similitude to the groups
of Cormorants, and other marine divers, which constitute an
effective part of the picturesque army of robbers of the sea. "

Another extraordinary and interesting group of the Meso-
zoic Reptiles is constituted by the Deinosauria, comprising a
series of mostly gigantic forms, which range from the Trias to
the Chalk. All the " Deinosaurs " are possessed of the two pairs
of limbs proper to Vertebrate animals, and these organs are in
the main adapted for walking on the dry land. Thus, whilst

256

HISTORICAL PALEONTOLOGY.

the Mesozoic seas swarmed with the huge Ichthyosaurs and
Plesiosaurs, and whilst the air was tenanted by the Dragon-like
Pterosaurs, the land-surfaces of the Secondary period were
peopled by numerous forms of Deinosaurs, some of them of
even more gigantic dimensions than their marine brethren.
The limbs of the Deinosaurs are, as just said, adapted for pro-
gression on the land; but in some cases, at any rate, the
hind-limbs were much longer and stronger than the fore-limbs;
and there seems to be no reason to doubt that many of these
forms possessed the power of walking, temporarily or perman-
ently, on their hind-legs, thus presenting a singular resemblance
to Birds. Some very curious and striking points connected
with the structure of the skeleton have also been shown to
connect these strange Reptiles with the true Birds ; and such
high authorities as Professors Huxley and Cope are of opinion
that the Deinosaurs are distinctly related to this class, being in
some respects intermediate between the proper Reptiles and
the great wingless Birds, like the Ostrich and Cassowary. On
the other hand, Professor Owen has shown that the Deinosaurs
possess some weighty points of relationship with the so-called

Fig. 180.— Skull of Megalosaurus, on a scale one-tenth of nature. Restored.
(After Professor Phillips.)

" Pachydermatous " Quadrupeds, such as the Rhinoceros and
Hippopotamus. The most important Jurassic genera of
Deinosauria are Megalosaurus and Cetiosaurus, both of which
extend their range into the Cretaceous period, in which
flourished, as we shall see, some other well-known members
of this order.

THE JURASSIC PERIOD. 257

Megalosaurus attained gigantic dimensions, its thigh and
shank bones measuring each about three feet in length, and its
total length, including the tail, being estimated at from forty
to fifty feet. As the head of the thigh-bone is set on nearly
at right angles with the shaft, whilst all the long bones of the
skeleton are hollowed out internally for the reception of the
marrow, there can be no doubt as to the terrestrial habits of
the animal. The skull (fig. 180) was of large size, four or five
feet in length, and the jaws were armed with a series of power-
ful pointed teeth. The teeth are conical in shape, but are
strongly compressed towards their summits, their lateral edges
being finely serrated. In their form and their saw-like edges,
they resemble the teeth of the " Sabre-toothed Tiger " Machai-
rodus}, and they render it certain that the Megalosaur was in
the highest degree destructive and carnivorous in its habits.
So far as is known, the skin was not furnished with any armor
of scales or bony plates ; and the fore-limbs are so dispro-
portionately small as compared with the hind-limbs, that this
huge Reptile — like the equally huge Iguanodon — may be
conjectured to have commonly supported itself on its hind-
legs only.

The Cetiosaur attained dimensions even greater than those
of the Megalosaur, one of the largest thigh-bones measuring
over five feet in length and a foot in diameter in the middle,
and the total length of the animal being probably not less than
fifty feet. It was originally regarded as a gigantic Crocodile,
but it has been shown to be a true Deinosaur. Having ob-
tained a magnificent series of remains of this reptile, Professor
Phillips has been able to determine many very interesting
points as to the anatomy and habits of this colossal animal,
the total length of which he estimates as being probably not
less than sixty or seventy feet. As to its mode of life, this
accomplished writer remarks : —

" Probably when ' standing at ease ' not less than ten feet
in height, and of a bulk in proportion, this creature was un-
matched in magnitude and physical strength by any of the
largest inhabitants of the Mesozoic land or sea. Did it live
in the sea, in fresh waters, or on the land? This question
cannot be answered, as in the case of Ichthyosaurus, by appeal
to the accompanying organic remains ; for some of the bones
lie in marine deposits, others in situations marked by estuarine
conditions, and, out of the Oxfordshire district, in Sussex, in
fluviatile accumulations. Was it fitted to live exclusively in
17

258 HISTORICAL PALEONTOLOGY.

water? Such an idea was at one time entertained, in conse-
quence of the biconcave character of the caudal vertebrae, and
it is often suggested by the mere magnitude of the creature,
which would seem to have an easier life while floating in water,
than when painfully lifting its huge bulk, and moving with
slow steps along the ground. But neither of these arguments
is valid. The ancient earth was trodden by larger quadrupeds
than our elephant; and the biconcave character of vertebrae,
which is not uniform along the column in Cetiosaurus, is per-
haps as much a character of geological period as of a me-
chanical function of life. Good evidence of continual life in
water is yielded in the case of Ichthyosaurus and other Ena-
liosaurs, by the articulating surfaces of their limb-bones, for
these, all of them, to the last phalanx, have that slight and
indefinite adjustment of the bones, with much intervening
cartilage, which fits the leg to be both a flexible and forcible
instrument of natation, much superior to the ordinary oar-
blade of the boatman. On the contrary, in Cetiosaur, as well
as in Megalosaur and Iguanodon, all the articulations are
definite, and made so as to correspond to determinate move-
ments in particular directions, and these are such as to be
suited for walking. In particular, the femur, by its head pro-
jecting freely from the acetabulum, seems to claim a movement
of free stepping more parallel to the line of the body, and
more approaching to the vertical than the sprawling gait of
the crocodile. The large claws concur in this indication of
terrestrial habits. But, on the other hand, these characters
are not contrary to the belief that the animal may have been
amphibious ; and the great vertical height of the anterior part
of the tail seems to support this explanation, but it does not
go further. . . . We have therefore a marsh-loving or
river-side animal, dwelling amidst filicine, cycadaceous, and
coniferous shrubs and trees full of insects and small mamma-
lia. What was its usual diet? If ex ungue leonem, surely ex
dente cibum. We have indeed but one tooth, and that small
and incomplete. It resembles more the tooth of Iguanodon
than that of any other reptile; for this reason it seems prob-
able that the animal was nourished by similar vegetable food
which abounded in the vicinity, and was not obliged to con-
tend with Megalosaurus for a scanty supply of more stimu-
lating diet. "

All the groups of Jurassic Reptiles which we have hitherto
been considering are wholly unrepresented at the present day,

THE JURASSIC PERIOD.

259

3.nd do not even pass upwards into the Tertiary period. It
may be mentioned, however, that the Oolitic deposits have
also yielded the remains of Reptiles belonging to three of the
existing orders of the class — namely, the Lizards (Lacertilia),

Fig. 181. — Arc/tcKopteryx macrura, showing tall and tail-feathers, with detached bones.
Reduced. From the Lithographic Slate of Solenhofen.

the Turtles (Chelonia}, and the Crocodiles (Crocodilia). The
Lizards occur both in the marine strata of the Middle Oolites
and also in the fresh-water beds of the Purbeck series; and

Fig. 182.— Restoration of Arckceopteryx macrura. (After Owen).

they are of such a nature that their affinities with the typical
Lacertilians of the present day cannot be disputed. The
Chelonians, up to this point only known by the doubtful evi-

260 HISTORICAL PALEONTOLOGY.

dence of footprints in the Permian and Triassic sandstones, are
here represented by unquestionable remains, indicating the ex-
istence of marine Turtles (the Chelone planiceps of the Portland
Stone). No remains of Serpents (Ophidians} have as yet been
detected in the Jurassic; but strata of this age have yielded
the remains of numerous Crocodilians, which probably inhab-
ited the sea. The most important member of this group is
Teleosaurus, which attained a length of over thirty feet, and
is in some respects allied to the living Gavials of India.

The great class of the Birds, as we have seen, is represented
in rocks earlier than the Oolites simply by the not absolutely
certain evidence of the three-toed footprints of the Connecti-
cut Trias. In the Lithographic Slate of Solenhofen (Middle
Oolite), there has been discovered, however, the at present
unique skeleton of a Bird well known under the name of the
Archaopteryx macrura (figs. 181, 182). The only known
specimen — now in the British Museum — unfortunately does
not exhibit the skull ; but the fine-grained matrix has pre-
served a number of the other bones of the skeleton, along with
the impressions of the tail and wing feathers. From these
remains we know that Archaopteryx differed in some remark-
able peculiarities of its structure from all existing members of
the class of Birds. This extraordinary Bird (fig. 182) appears
to have been about as big as a Rook — the tail being long and
extremely slender, and composed of separate vertebrae, each
of which supports a single pair of quill-feathers. In the flying
Birds of the present day, as before mentioned, the terminal
vertebrae of the tail are amalgamated to form a single bone
("ploughshare-bone"), which supports a cluster of tail-feathers;
and the tail itself is short. In the embryos of existing Birds
the tail is long, and is made up of separate vertebrae, and the
same character is observed in many existing Reptiles. The
tail of Archoeopteryx, therefore, is to be regarded as the per-
manent retention of an embryonic type of structure, or as an
approximation to the characters of the Reptiles. Another
remarkable point in connection with Archaopteryx, in which
it differs from all known Birds is, that the wing was furnished
with two free claws. From the presence of feathers, Archce-
opteryx may be inferred to have been hot-blooded; and this
character, taken along with the structure of the skeleton of the
wing, may be held as sufficient to justify its being considered
as belonging to a class of Birds. In the structure of the
tail, however, it is singularly Reptilian; and there is reason to

THE JURASSIC PERIOD.

261

believe that its jaws were furnished with teeth sunk in distinct
sockets, as is the case in no existing Bird. This conclusion,
at any rate, is rendered highly probable by the recent discovery
of "Toothed Birds" (Odontornithes) in the Cretaceous rocks
of North America.

The Mammals of the Jurassic period are known to us by
a number of small forms which occur in the " Stonesfield
Slate" (Great Oolite) and in the Purbeck beds (Upper
Oolite). The remains of these are almost exclusively sepa-
rated halves of the lower jaw, and they indicate the existence

Fig. 183. — Lower jaw of Ampkitherium ( Thylacotherium) PrevosM,
Stonesfield Slate (Great Oolite.)

during the Oolitic period in Europe of a number of small
"Pouched animals" (Marsupials). In the horizon of the
Stonesfield Slate four genera of these little Quadrupeds have
been described — viz., Amphilestes, Amphitherium, Phascolo-
therium, and Stereognathus. In Amphitherium (fig. 183), the
molar teeth are 'furnished with small pointed eminences of
" cusps ; " and the animal was doubtless insectivorous. By

Fig. 184 —Oolitic Mammals.— 1, Lower jaw and teeth of Pkaacolotherium, Stones-
field Slate ; 2. Lower jaw and teeth of Amphitherium, Stonesfield Slate ; 3, Lower jaw
and teeth of Triconodon. Purbeck beds ; 4. Lower jaw and teeth of Plagiaulax, Pur-
beck beds. All the figures are of the natural size.

Professor Owen, the highest living authority on the subject,
Amphitherium is believed to be a small Marsupial, most
nearly allied to the living Banded Ant-eater (Myrmecobius) of
Australia (fig. 158). Amphilestes and Phascolotherium (fig.

262 HISTORICAL PALEONTOLOGY.

184) are also believed by the same distinguished anatomist
and palaeontologist to have been insect-eating Marsupials, and
the latter is supposed to find its nearest living ally in the
Opossums (Didelphys) of America. Lastly, the Stereognathus
of the Stonesfield Slate is in a dubious position. It may have
been a Marsupial; but, upon the whole, Professor Owen is
inclined to believe that it must have been a hoofed and her-
bivorous Quadruped belonging to the series of the higher Mam-
mals (Placentalia). In the Middle Purbeck beds, near to the
close of the Oolitic period, we have also evidence of the exist-
ence of a number of small Mammals, all of which are probably
Marsupials. Fourteen species are known, all of small size,
the largest being no bigger than a Polecat or Hedgehog. The
genera to which these little quadrupeds have been referred are
Plagiaulax, Spalacotherium, Triconodon, and Galestes. The
first of these (fig. 184, 4) is believed by Professor Owen to
have been carnivorous in its habits ; but other authorities
maintain that it was most nearly allied to the living Kangaroo-
rats (Hypsiprymnus} of Australia, and that it was essentially
herbivorous. The remaining three genera appear to have
been certainly insectivorous, and find their nearest living rep-
resentatives in the Australian Phalangers and the American
Opossums.

Finally, it is interesting to notice in how many respects the
Jurassic fauna of Western Europe approached to that now
inhabiting Australia. At the present day, Australia is almost
wholly tenanted by Marsupials; upon its land-surface flourish
Araucarice and Cycadaceous plants, and in its seas swim the
Port-Jackson Shark (Ccstracion Philip pi*) ; whilst the Mollus-
can genus Trigonia is nowadays exclusively confined to the
Australian coasts. In England, at the time of the deposition
of the Jurassic rocks, we must have had a fauna and flora very
closely resembling what we now see in Australia. The small
Marsupials, Amphitherium, Phascolotherium, and others, prove
jhat the Mammals were the same in order; cones of Arau-
carian pines, with tree-ferns and fronds of Cycads, occur
throughout the Oolitic series; spine-bearing fishes, like the
Port-Jackson Shark, are abundantly represented by genera
such as Acrodus and Strophodus; and lastly, the genus Tri-
gonia, now exclusively Australian, is represented in the Oolites
by species which differ little from those now existing. More-
over, the discovery during recent years of the singularMud-fish,
the Ceratodus Fosteri, in the rivers of Queensland, has added

THE JURASSIC PERIOD. 263

another and a very striking point of resemblance to those
already mentioned; since this genus of Fishes, though pre-
eminently Triassic, nevertheless extended its range into the
Jurassic. Upon the whole, therefore, there is reason to con-
clude that Australia has undergone since the close of the
Jurassic period fewer changes and vicissitudes than any other
known region of the globe ; and that this wonderful continent
has therefore succeeded in preserving a greater number of
the characteristic life-features of the Oolites than any other
country with which we are acquainted.

LITERATURE.

The following list comprises some of the more important
sources of information as to the rocks and fossils of the Juras-
sic series : —

(1) 'Geology of Oxford and the Thames Valley.' Phillips.

(2) ' Geology of Yorkshire, ' vol. ii. Phillips.

(3) ' Memoirs of the Geological Survey of Great Britain. '

(4) ' Geology of Cheltenham. ' Murchison, 2d ed. Buckman.

(5) ' Introduction to the Monograph of the Oolitic Aster-

iadas ' (Palaeontographical Society). Wright.

(6) " Zone of Avicula contorta and the Lower Lias of the

South of England " — ' Quart. Journ Soc., ' vol. xvi.,
1860. Wright.

(7) " Oolites of Northamptonshire " — ' Quart. Journ. Geol.

Soc., ' vols. xxvi. and xxix. Sharp.

(8) ' Manual of Geology. ' Dana.

(9) ' Der Jura. ' Quenstedt.

(10) 'Das Flotzgebirge Wurttembergs. ' Quenstedt.

(n) 'Jura Formation.' Oppel.

(12) ' Paleontologie du Departement de la Moselle.' Terquem.

(13) ' Cours elementaire de Paleontologie.' D'Orbigny.

(14) 'Paleontologie Franchise. ' D'Orbigny.

(15) 'Fossil Echinodermata of the Oolitic Formation.'

(Palaeontographical Society). Wright.

(16) ' Brachiopoda of the Oolitic Formation' (Palaeon-

tographical Society). Davidson.

(17) ' Mollusca of the Great Oolite' ( Palaeontographical So-

ciety). Morris and Lycett.

(18) 'Monograph of the Fossil Trigoniae* (Palaeontographical

Society). Lycett.

(19) 'Corals of the Oolitic Formation' (Palaeontographical

Society). Edwards and Haime.

(20) ' Supplement to the Corals of the Oolitic Formation '

(Palaeontographical Society). Martin Duncan.

(21) 'Monograph of the Belemnitidae ' (Palaeontographical

Society). Phillips.

(22) 'Structure of the Belemnitidae' (Mem. Geol. Survey).

Huxley.

264 HISTORICAL PALAEONTOLOGY.

(23) ' Sur les Belemnites. ' Blainville.

(24) ' Cephalopoden. ' Quenstedt.

(25) ' Mineral Conchology. ' Sowerby.

(26) 'Jurassic Cephalopoda' ( Palaeontologica Indica). Waa-

gen.

(27) 'Manual of the Mollusca. ' Woodward.

(28) ' Petrefaktenkunde. ' Schlotheim.

(29) ' Bridgewater Treatise. ' Buckland.

(30) ' Versteinerungen des Oolithengebirges. ' Roemer.

(31) 'Catalogue of British Fossils.' Morris.

(32) ' Catalogue of Fossils in the Museum of Practical Geol-

ogy. ' Etheridge.

(33) ' Beitrage zur Petrefaktenkunde.' Miinster.

(34) ' Petrefacta Germanise. ' Goldfuss.

(35) ' Lethcea Rossica. ' Eichwald.

(36) 'Fossil Fishes' (Decades of the Geol. Survey). Sir

Philip Egerton.

(37) ' Manual of Palaeontology. ' Owen.

(38) ' British Fossil Mammals and Birds. ' Owen.

(39)' Monographs of the Fossil Reptiles of the Oolitic For-
mation.' (Palseontographical Society). Owen.

(40) ' Fossil Mammals of the Mesozoic Formations ' Palae-
ontographical Society). Owen.

(41) 'Catalogue of Ornithosauria. ' Seeley.
(42)

' Classification of the Deinosauria " — ' Quart. Journ. Geol.
Soc., ' vol. xxvi., 1870. Huxley.

CHAPTER XVII.
THE CRETACEOUS PERIOD.

The next series of rocks in ascending order is the great and
important series of the Cretaceous Rocks, so called from the
general occurrence in the system of chalk (Lat. creta, chalk).
As developed in Britain and Europe generally, the following
leading subdivisions may be recognized in the Cretaceous
series : —

2. Lowefcreensand or Neocomian, } Lower Cretaceous.

3. Gault, >,

4. Upper Greensand, TT ^

5. Chalk, § [ UPPer Cretaceous.

6. Maestricht beds,

I. Wealden. — The Wealden formation, though of consider-

THE CRETACEOUS PERIOD. 265

able importance, is a local group, and is confined to the south-
east of England, France, and some other parts of Europe. Its
name is derived from the Weald, a district comprising parts of
Surrey, Sussex, and Kent, where it is largely developed. Its
lower portion, for a thickness of from 500 to 1000 feet, is
arenaceous, and is known as the Hastings Sands. Its Upper
portion, for a thickness of 150 to nearly 300 feet, is chiefly
argillaceous, consisting of clays with sandy layers, and occa-
sionally courses of limestone. The geological importance of
the Wealden formation is very great, as it is undoubtedly the
delta of an ancient river, being composed almost wholly of
fresh-water beds, with a few brackish-water and even marine
strata, intercalated in the lower portion. Its geographical
extent, though uncertain, owing to the enormous denudation
to which it has been subjected, is nevertheless great, since it
extends from Dorsetshire to France, and occurs also in North
Germany. Still, even if it were continuous between all these
points, it would not be larger than the delta of such a modern
river as the Ganges. The river which produced the Wealden
series must have flowed from an ancient continent occupying
what is now the Atlantic Ocean ; and the time occupied in
the formation of the Wealden must have been very great,
though we have, of course, no data by which we can accurately
calculate its duration.

The fossils of the Wealden series are, naturally, mostly the
remains of such animals as we know at the present day as in-
habiting rivers. We have, namely, fresh-water Mussels (Unto),
River-snails (Paludina'), and other fresh-water shells, with
numerous little bivalved Crustaceans, and some fishes.

II. Lower Greensand (Niocomien of D'Orbigny). — The
Wealden beds pass upward, often by insensible gradations,
into the Lower Greensand. The name Lower Greensand is
not an appropriate one, for green sands only occur sparingly
and occasionally, and are found in other formations. For this
reason it has been proposed to substitute for Lower Greensand
the name Neocomian, derived from the town of Neufchatel —
anciently called Neocomum — in Switzerland. If this name
were adopted, as it ought to be, the Wealden beds would be
called the Lower Neocomian.

The Lower Greensand or Neocomian of Britain has a thick-
ness of about 850 feet, and consists of alternations of sands,
sandstones, and clays, with occasional calcareous bands. The
general color of the series is dark brown, sometimes red; and

266 HISTORICAL PALEONTOLOGY.

the sands are occasionally green, from the presence of silicate
of iron.

The fossils of the Lower Greensand are purely marine, and
among the most characteristic are the shells of Cephalopoda.

The most remarkable point, however, about the fossils of
the Lower Cretaceous series, is their marked divergence from
the fossils of the Upper Cretaceous rocks. Of 280 species of
fossils in the Lower Cretaceous series, only 51, or about 18
per cent, pass on into the Upper Cretaceous. This break in
the life of the two periods is accompanied by a decided phy-
sical break as well; for the Gault is often, if not always, un-
conformably superimposed on the Lower Greensand. At the
same time, the Lower and Upper Cretaceous groups form a
closely-connected and inseparable series, as shown by a com-
parison of their fossils with those of the underlying Jurassic
rocks and the overlying Tertiary beds. Thus, in Britain no
marine fossil is known to be common to the marine beds of
the Upper Oolites and the Lower Greensand ; and of more
than 500 species of fossils in the Upper Cretaceous rocks,
almost every one died out before the formation of the lowest
Tertiary strata, the only survivors being one Brachiopod and a
few Foraminifera.

III. Gault (Aptien of D'Orbigny). — The lowest member of
the Upper Cretaceous series is a stiff, dark-grey, blue, or
brown clay, often worked for brick-making, and known as the
Gault, from a provincial English term. It occurs chiefly in
the southeast of England, but can be traced through France
to the flanks of the Alps and Bavaria. It never exceeds 100
feet in thickness; but it contains many fossils, usually in a
state of beautiful preservation.

IV. Upper Greensand (Albien of D'Orbigny; Unterquader
and Lower Planerkalk of Germany). — The Gault is succeeded
upward by the Upper Greensand, which varies in thickness
from 3 up to 100 feet, and which derives its name from the
occasional occurrence in it of green sands. These, however,
are local and sometimes wanting, and the name "Upper
Greensand" is to be regarded as a name and not a description.
The group consists, in Britain, of sands and clays, sometimes
with bands of calcareous grit or siliceous limestone, and occa-
sionally containing concretions of phosphate of lime, which are
largely worked for agricultural purposes.

V. White Chalk. — The top of the Upper Greensand be-
comes argillaceous, and passes up gradually into the base of

THE CRETACEOUS PERIOD. 267

the great formation known as the true Chalk, divided into
the three subdivisions of the chalk-marl, white chalk without
flints, and white chalk with flints. The first of these is sim-
ply argillaceous chalk, and passes up into a great mass of
obscurely-stratified white chalk in which there are no flints
(Turonien of D'Orbigny; Mittelquader of Germany). This in
turn, passes up into a great mass of white chalk, in which the
stratification is marked by nodules of black flint arranged in
layers (Sffnonien of D'Orbigny; Oberquadcr of Germany). T.h*
thickness of these three subdivisions taken together is some
times over 1000 feet, and their geographical extent is ven
great. White Chalk, with its characteristic appearance, may
be traced from the north of Ireland to the Crimea, a distance
of about 1 140 geographical miles ; and, in an opposite direction,
from the south of Sweden to Bordeaux, a distance of about
840 geographical miles.

VI. In Britain there occur no beds containing Chalk fossils,
or in any way referable to the Cretaceous period, above the
true White Chalk with flints. On the banks of the Maes,
however, near Maestricht in Holland, there occurs a series of
yellowish limestones, of about 100 feet in thickness, and un-
doubtedly superior to the White Chalk. These Maestricht
beds (Danien of D'Orbigny) contain a remarkable series of
fossils, the characters of which are partly Cretaceous and
partly Tertiary. Thus, with the characteristic Chalk fossils,
Belemnites, Baculites, Sea-urchins, &c., are numerous Univalves
Molluscs, such as Cowries and Volutes, which are otherwise
exclusively Tertiary or Recent.

Holding a similar position to the Maestricht beds, and
showing a similar intermixture of Cretaceous forms with later
types, are certain beds which occur in the island of Seeland,
in Denmark, and which are known as the Fax'oe Limestone.

Of a somewhat later date than the Maestricht beds is the
Pisolitic Limestone of France, which rests unconformably on
the White Chalk, and contains a large number of Tertiary
fossils along with some characteristic Cretaceous types.

The subjoined sketch-section exhibits the general succession
of the Cretaceous deposits in Britain : —

268

HISTORICAL PALAEONTOLOGY.

GENERALIZED SECTION OF THE CRETACEOUS SERIES
OF BRITAIN.

Fig. 185.

Eocene.

White Chalk with Flints.

- White Chalk without Flints.

.. Chalk Marl.

... Upper Greensand.

~ Gault.

Lower Greensand or
Neocomian.

Wreald Clay.

> ., Wealden Series.

Hastings Sands.

In North America, strata of Lower Cretaceous age are well
represented in Missouri, Wyoming, Utah, and in some other
areas ; but the greater portion of the American deposits of
this period are referable to the Upper Cretaceous. The rocks

THE CRETACEOUS PERIOD. 269

of this series are mostly sands, clays, and limestones — Chalk
itself being unknown except in Western Arkansas. Amongst
the sandy accumulations, one of the most important is the so-
called " marl " of New Jersey, which is truly a " Greensand, "
and contains a large proportion of glauconite (silicate of iron
and potash). It also contains a little phosphate of lime, and is
largely worked for agricultural purposes. The greatest thick-
ness attained by the Cretaceous rocks of North America is
about 9000 feet, as in Wyoming, Utah, and Colorado. Ac-
cording to Dana, the Cretaceous rocks of the Rocky Mountain
territories pass upwards " without interruption into a coal-
bearing formation, several thousand feet thick, on which the
following Tertiary strata lie unconformably. " The lower por-
tion of this " Lignitic formation " appears to be Cretaceous,
and contains one or more beds of Coal ; but the upper part of it
perhaps belongs to the Lower Tertiary. In America, therefore,
the lowest Tertiary strata appear to rest conformably upon the
highest Cretaceous ; whereas in Europe, the succession at this
point is invariably an unconformable one. Owing, however, to
the fact that the American " Lignitic formation " is a shallow-
water formation, it can hardly be expected to yield much
material whereby to bridge over the great palaeontological gap
between the White Chalk and Eocene in the Old World.

Owing to the fact that so large a portion of the Cretaceous
formation has been deposited in the sea, much of it in deep
water, the plants of the period have for the most part been
found special members of the series, such as the Wealden beds,
the Aix-la-Chapelle sands, and the Lignitic beds of North
America. Even the purely marine strata, however, have
yielded plant remains, some of these are peculiar and
proper to the deep-sea deposits of the series. Thus the little
calcareous discs termed " coccoliths, " which are known to be
of the nature of calcareous sea-weeds (Alga} have been de-
tected in the White Chalk; and the flints of the same forma-
tion commonly contain the spore-cases of the microscopic
Desmids (the so-called Xanthidia), along with the siliceous cases
of the equally diminutive Diatoms.

The plant-remains of the Lower Cretaceous greatly resemble
those of the Jurassic period, consisting mainly of Ferns, Cy-
cads, and Conifers. The Upper Cretaceous rocks, however,
both in Europe and in North America, have yielded an abun-
dant flora which resembles the existing vegetation of the globe
in consisting mainly of Angiospermous Exogens and of Mono-

270 HISTORICAL PALAEONTOLOGY.

cotyledons. * In Europe the plant-remains in question have
been found chiefly in certain sands in the neighborhood of Aix-
la-Chapelle, and they consist of numerous Ferns, Conifers (such
as Cycadopteris}, Screw Pines (Pandanus), Oaks (Quercus),
Walnut (Juglans}, Fig. (Ficus}, and many Proteacea, some of
which are referred to existing genera (Dryandra, Banksia,
Grevillea, &c.)

In North America, the Cretaceous strata of New Jersey,
Alabama, Nebraska, Kansas, &c., have yielded the remains of
numerous plants, many of which belong to existing genera.
Amongst these may be mentioned Tulip-trees (Liriodendron),
Sassafras (fig. 186), Oaks (Quercus), Beeches (Fagus*), Plane-
trees (Platanus}, Alders (Alnus), Dog-wood (Cornus}, Willows
(Salix), Poplars (Populus}, Cypresses (Cupressus}, Bald Cy-
presses (Tax odium}, Magnolias, &c. Besides these, however,
there occur other forms which have now entirely disappeared
from North America — as, for example, species of Cinnamomum
and Araucaria.

It follows from the above, that the Lower and Upper Creta-
ceous rocks are, from a botanical point of view, sharply sepa-
rated from one another. The Palaeozoic period, as we have
seen, is characterized by the prevalence of " Flowerless " plants
(Cryptogams}, its higher vegetation consisting almost exclu-
sively of Conifers. The Mesozoic period, as a whole, is charac-
terized by the prevalence of the Cryptogamic group of the
Ferns, and the Gymnospermic groups of the Conifers and the
Cycads. Up to the close of the Lower Cretaceous, no Angio-
spermous Exogens are certainly known to have existed, and
Monocotyledonous plants or Endogens are very poorly repre-
sented. WTith the Upper Cretaceous, however, a new era of
plant-life, of which our present is but the culmination, com-
menced, with a great and apparently sudden development of new
forms. In place of the Ferns, Cycads, and Conifers of the earlier

* The " Flowering plants " are divided into the two great groups of
the Endogens and Exogens. The Endogens (such as Grasses, Palms, Lilies,
&c.) have no true bark, nor rings of growth, and the stem is said to be
" endogenous ;" the young plant also possesses but a single seed-leaf or
"cotyledon." Hence" these plants are often simply called "Monocotyledons."
The Exogens, on the other hand, have a true bark ; and the stem increases
by annual additions to the outside, so that rings of growth are produced.
The young plant has two seed-leaves or " cotyledons," and these plants
are therefore called " Dicotyledons." Amongst the Exogens, the Pines
(Conifers') and the Cycads have seeds which are unprotected by a seed-
vessel, and they are therefore called "Gymnosperms" All the other Exo-
gens, including the ordinary trees, shrubs, and flowering plants, have the
seeds enclosed in a seed-vessel, and are therefore called " Angiosperms."
The derivation of these terms will be found in the Glossary at the end of
the volume.

THE CRETACEOUS PERIOD.

271

Mesozoic deposits, we have now an astonishingly large number
of true Angiospermous Exogens, many of them belonging to
existing types; and along with these are various Monocotyle-
donous plants, including the first examples of the great and im-
portant group of the Palms. It is thus a matter of interest to
reflect that plants closely related to those now inhabiting the
earth, were in existence at a time when the ocean was tenanted
by Ammonites and Belemnites, and when land and sea and
air were peopled by the extraordinary extinct Reptiles of the
Mesozoic period.

As regards animal life, the Protozoans of the Cretaceous
period are exceedingly numerous, and are represented by Fora-

?. 186. — Cretaceous Angiosperms. a. Sassafras Cretaceum; b, Liriodendron
Meekii; c, Leguminositea Marcouanus; d, Salix Meekii. (After Dana.)

minifera and Sponges. As we have already seen, the White
Chalk itself is a deep-sea deposit, almost entirely composed
of the microscopic shells of Foraminifers, along with Sponge-
spicules, and organic debris of different kinds (see p. 23, fig. 7).
The green grains which are abundant in several minor sub-

272 HISTORICAL PALEONTOLOGY.

divisions of the Cretaceous, are also in many instances really
casts in glauconite of the chambered shells of these minute
organisms. A great many species of Foraminifera have been
recognized in the Chalk ; but the three principal genera are

Fig. 187. — Rotalia Boueana.

Globigerina, Rotalia (fig. 187), and Textularia — groups which
are likewise characteristic of the "ooze" of the Atlantic and
Pacific Oceans at great depths. The flints of the Chalk also
commonly contain the shells of Foraminifera. The Upper
Greensand has yielded in considerable numbers the huge
Foraminifera described by Dr. Carpenter under the name of
Parkeria, the spherical shells of which are composed of sand-
grains agglutinated together, and sometimes attain a diameter
of two and a quarter inches. The Cretaceous Sponges are
extremely numerous, and occur under a great number of varie-
ties of shape and structure ; but the two most characteristic
genera are Siphonia and Ventriculites, both of which are ex-
clusively confined to strata of this age. The Siphonia (fig.
188) consist of a pear-shaped, sometimes lobed head, supported
by a longer or shorter stem, which breaks up at its base into a
number of root-like processes of attachment. The water gained
access to the interior of the Sponge by a number of minute
openings covering the surface, and ultimately escaped by a
single, large, chimney-shaped aperture at the summit. In some
respects these sponges present, a singular resemblance to the
beautiful " Vitreous Sponges " (Holtenia or Pheronema} of the
deep Atlantic ; and, like these, they were probably denizens
of a deep sea. The Ventriculites of the Chalk (fig. 189) is,
however, a genus still more closely allied to the wonderful
flint Sponges, which have been shown, by the researches of
the Porcupine, Lightning, and Challenger expeditions, to live
half buried in the calcareous ooze of the abysses of our great
oceans. Many forms of this genus are known, having "usu-
ally the form of graceful vases, tubes, or funnels, variously

THE CRETACEOUS PERIOD.

273

ridged or grooved, or otherwise ornamented on the surface,
frequently expanded above into a cup-like lip, and continued
below into a bundle of fibrous roots. The minute structure of
these bodies shows an extremely delicate tracery of fine tubes,
sometimes empty, sometimes filled with loose calcareous mat-
ter dyed with peroxide of iron. " — (Sir Wyville Thomson.)
Many of the Chalk sponges, originally calcareous, have been
converted into flint subsequently; but the Ventriculites are
really composed of this substance, and are therefore genuine
" Siliceous Sponges, " like the existing Venus's Flower-basket
(Euplectella}. Like the latter, the skeleton was doubtless orig-
inally composed, in the young state, of disconnected six-
rayed spicules, which ultimately become fixed together to
constitute a continuous frame-work. The sea-water, as in the
recent forms, must have been admilted to the interior of the
Sponge by numerous apertures on its exterior, subsequently
escaping by a single large opening at its summit.

Fig. ISS.—Sipfionia flcu».
Upper Greensand, Europe.

Fig. ISQ.—VentricuUtes simplex.
White Chalk, Britain.

Amongst the Ccelentcrates, the " Hydroid Zoophytes " are
represented by a species of the encrusting genus Hydractinia,
the horny polypary of which is so commonly found at the
18

274

HISTORICAL PALEONTOLOGY.

present day adhering to the exterior of shells. The occurrence
of this genus is of interest, because it is the first known instance
in the entire geological series of the occurrence of an unques-

Flg. IQO.—Synfielia Sharpeana. Chalk, England.

tionable Hydroid of a modern type, though many of the exist-
ing forms of these animals possess structures which are per-
fectly fitted for preservation in the fossil condition. The corals
of the Cretaceous series are not very numerous, and for the
most part are referable to types such as Trochocyathus, Stephano-
pliyllia, Parasmilia, Synhelia (fig. 190), &c., which belong to
the same great group of corals as the majority of existing
forms. We have also a few "Tabulate Corals" (Polytre-
macis), hardly, if at all, generically separable from very ancient
forms (Heliolites) ; and the Lower Greensand has yielded the
remains of the little Plolocystis elegans, long believed to be the
last of the great Palaeozoic group of the Rugosa.

As regards the Echinoderms, the group of the Crinoids now
exhibits a marked decrease in the number and variety of its
types. The " stalked " forms are represented by Pentacrinus
and Bourgueticrinus, and the free forms by Feather-stars like
our existing Comatulce; whilst a link between the stalked and
free groups is constituted by the curious " Tortoise Encrinite
(Marsupites). By far the most abundant Cretaceous Echino-
derms, however, are Sea-urchins (Echinoids) ; though several
Star-fishes are known as well. The remains of Sea-urchins are
so abundant in various parts of the Cretaceous series, especially
in the White Chalk, and are often so beautifully preserved,

THE CRETACEOUS PERIOD.

275

that they constitute one of the most marked features of the
fauna of the period. From the many genera of Sea-urchins
which occur in strata of this age, it is difficult to select char-
acteristic types; but the genera Galerites (fig. 191), Discoidea
(fig. 192), Micraster, Ananchytes, Diadema, Salenia, and Ci-
daris, may be mentioned as being all important Cretaceous
groups.

Coming to the Annulose Animals of the Cretaceous period,
there is little special to remark. The Crustaceans belong for
the most part to the highly-organized groups of the Lobsters

Fig. 191. — Galerites albogalerw, viewed from below, from the side, and from above.
White Chalk.

and the Crabs (the Macrurous and Brachyurous Decapods) ;
but there are also numerous little Ostracodes, especially in the
fresh-water strata of the Wealden. It should further be noted

Fig. 192. — Discoidea cylindrica; under, side, and upper aspect.
Upper Greensand.

that there occurs here a great development of the singular
Crustaceans family of the Barnacles (Lepadida}, whilst the allied
family of the equally singular Acorn-shells (Balanida} is feebly
represented as well.

Passing on to the Mollusca, the class of the Sea-mats arid
Sea-mosses (Polysoa) is immensely developed in the Cretaceous
period, nearly two hundred species being known to occur in
the Chalk. Most of the Cretaceous forms belong to the family

276

HISTORICAL PALEONTOLOGY.

of the Escharidce, the genera Eschar a and Escharina (fig. 193)
being particularly well represented. Most of the Cretaceous
Polyzoans are of small size, but some7 attain considerable di-
mensions, and many simulate Corals in their general form and
appearance.

The Lamp-shells (Brachiopods) have now reached a further
stage of the progressive decline, which they have been under-
going ever since the close of
the Palaeozoic period. Though
individually not rare, especially
in certain minor subdivisions
of the series, the number of
generic types has now be-
come distinctly diminished, the
principal forms belonging to
the genera Terebratula, Tere-
bratella (fig. 194), Terebratulina,
Rhynchonella, and Crania (fig.
195). In the last mentioned

193.— A small fragment of Escharina
Oceani, of the natural size ; and a portion

of the same enlarged. Upper Greensand. of these> the shdl {s attached

to foreign bodies by the sub-
stance of one of the valves (the ventral), whilst the other or
free valve is more or less limpet-shaped. All the above-men-
tioned genera are in existence at the present day; and one
species — namely, Terebratulina striata — appears to be undis-
tinguishable from one now living — the Terebratulina caput-
serpentis.

Whilst the Lamp-shells are slowly declining, the Bivalves
(Lamellibranchs} are greatly developed, and are amongst the

. 194.— Terebratella Astieriana. Gault.

most abundant and characteristic fossils of the Cretaceous
period. In the great river-deposit of the Wealden, the Bivalves

THE CRETACEOUS PERIOD.

277

are forms proper to fresh water, belonging to the existing
River-mussels (Unio}, Cyrena and Cyclas; but most of the
Cretaceous Lamellibranchs are marine. Some of the most

Fig. 195. -Crania lanabergensis. The left-hand figure shows the perfect shell, at-
tached by its ventral valve to a foreign body ; the middle figure shows the exterior of
the limpet-shaped dorsal valve ; and the right-band figure represents the Interior of
the attached valve. White Chalk.

abundant and characteristic of these belong to the great family
of the Oysters (Ostreidce). Amongst these are the genera
Gryphcea and Exogyra, both of which we have seen to occur

Fig. 196.— Ostrea Couloni. Lower Greensand,

abundantly in the Jurassic ; and there are also numerous true
Oysters (Ostrea, fig. 196) and Thorny Oysters (Spondylus, fig.
197). The genus Trigonia, so characteristic of the Mesozoic
deposits in general, is likewise well represented in the Creta-
ceous strata. No single genus of Bivalves is, however, so highly
characteristic of the Cretaceous period as Inoceramus, a group
belonging to the family of the Pearl-mussels (Aviculida) . The
shells of this genus (fig. 198) have the valves unequal in size,

278 HISTORICAL PALAEONTOLOGY.

the larger valve often being much twisted, and both valves
being marked with radiating ribs or concentric furrows. The
hinge-line is long and straight, with numerous pits for the
attachment of the ligament which serves to open the shell.
Some of the Inocerami attain a length of two or three feet, and
fragments of the shell are often found perforated by boring

Fig. 19T.—Spondylu8Spinosu8. White Chalk.

Sponges. Another extraordinary family of Bivalves, which is
exclusively confined to the Cretaceous rocks, is that of the
Hippuritida. All the members of this group (fig. 199) were

Fig. 198.— Inoceramus sulcatus. Gault.

attached to foreign objects, and lived associated in beds, like
Oysters. The two valves of the shell are always altogether
unlike in sculpturing, appearance, shape, and size ; and the
cast of the interior of the shell is often extremely unlike the
form of the outer surface. The type-genus of the family is
Hippurites itself (fig. 199), in which the shell is in the shape of
a straight or slightly-twisted horn, sometimes a foot or more in
length, constituted by the attached lower valve, and closed
above by a small lid-like free upper valve. About a hundred
species of the family of the Hippuritida are known, all of these
being Cretaceous, and occurring in Britain (one species only),
in Southern Europe, the West Indies, North America, Algeria,

THE CRETACEOUS PERIOD.

279

and Egypt. Species of this family occur in such numbers in
certain compact marbles in the south of Europe, of the age of
the Upper Cretaceous (Lower Chalk), as to have given orgin
to the name of " Hippurite Limestones, " applied to these
strata.

Fig. 199. — Hippuritea Toucasiana.
A large individual, with two smaller
ones attached to it. Upper Cretace-
ous. South of Europe.

Tig. 200.— Valuta elongata.
White Chalk.

The Univalves (Caster o pods') of the Cretaceous period are
not very numerous, nor particularly remarkable. Along with
species of the persistent genus Pleurotcmaria and the Meso-
zoic Nerinaa, we meet with examples of such modern types
as Turritella and Natica, the Staircase-shells (Solarium}, the
Wentle-traps (Scalaria), the Carrier-shells (Phorus), &c. To-
wards the close of the Cretaceous period, and especially in
such transitional strata as the Maestricht beds, the Faxoe

280

HISTORICAL PALAEONTOLOGY.

Limestone, and the Pisolitic Limestone of France, we meet
with a number of carnivorous (" siphonostomatous ") Uni-
valves, in which the mouth of the shell is notched or pro-
duced into a canal. Amongst these it is interesting to
recognize examples of such existing genera as the Volutes
(Valuta, fig. 200), the Cowries (Cyprcca}, the Mitre-shells
(Mitra}, the Wing-shells (Strombus), the Scorpion-shells
(Pleroceras}, &c.

Upon the whole, the most characteristic of all the Creta-
ceous Molluscs are the Cephalopods, represented by the remains
of both Tetrabranchiate and Dibranchiate forms. Amongst the
former, the long-lived genus Nautilus (fig. 201) again reap-
pears, with its involute shell, its capacious body-chamber, its
simple septa between the air-chambers, and its nearly or quite
central siphuncle. The majority of the chambered Cephalo-
pods of the Cretaceous belong, however, to the complex and
beautiful family of the Ammonitida , with their elaborately
folded and lobed septa and dorsally-placed siphuncle. This

Fig. 201.— Different views of Nautilus Danicug. Faxoe Limestone
(Upper Cretaceous), Denmark.

family disappears wholly at the close of the Cretaceous period ;
but it approaching extinction, so far from being signalized by
any slow decrease and diminution in the number of specific
or generic types, seems to have been attended by the develop-
ment of whole series of new forms. The genus Ammonites
itself, dating from the Carboniferous, has certainly passed its
prime, but it is still represented by many species, and some of
these attained enormous dimensions (two or three feet in
diameter). The genus Ancyloceras (fig. 202), though likewise
of more ancient origin (Jurassic), is nevertheless very charac-

THE CRETACEOUS PERIOD.

281

teristic of the Cretaceous. In this genus the first portion of
the shell is in the form of a flat spiral, the coils of which are
not in contact ; and its last portion is produced at a tangent,
becoming ultimately bent back in the form of a crosier. Be-

Fig. 202.— Ancyloceras Matheronianus . Gault.

sides these pre-existent types, the Cretaceous rocks have
yielded a great number of entirely new forms of the Ammoni-
tidcc, which are not known in any deposits of earlier or later
date. Amongst the more important of these may be men-
tioned Crioccras, Turrilites, Scaphites, Hamites, Ptychoceras,
and Baculites. In the genus Crioceras (fig. 204, d), the shell
consists of an open spiral, the volutions of which are not in
contact, thus resembling a partially-unrolled Ammonite or the
inner portion of an Ancyloceras. In Turrilites (fig. 203), the
shell is precisely like that of the Ammonite in its structure ;
but instead of forming a flat spiral, it is coiled into an ele-
vated turreted shell, the whorls of which are in contact with
one another. In the genus Scaphites (fig. 204, tf), the shell
resembles that of Ancyloceras in consisting of a series of volu-
tions coiled into a flat spiral, the last being detached from the
others, produced, and ultimately bent back in the form of a
crosier; but the whorls of the enrolled part of the shell are in
contact, instead of being separate as in the latter. In the
genus Hamites (fig. 204, /), the shell is an extremely elongated
cone, which is bent upon itself more than once, in a hook-like
manner, all the volution being separate. The genus Ptycho-
ceras (fig. 204, a) is very like Hamites, except that the shell is
only bent once ; and the two portions thus bent are in contact
with one another. Lastly, in the genus Baculites (fig. 201, b
and c) the shell is simply a straight elongated cone, not bent
in any way, but possessing the folded septa which characterize
the whole Ammonite family. The Baculite is the simplest of
all the forms of the Ammonitida; and all the other forms, how-

282

HISTORICAL PALAEONTOLOGY.

ever complex, may be regarded as being simply produced by
the bending or folding of such a conical septate shell in differ-
ent ways. The Baculite, therefore, corresponds, in the series

Fig, 203. — Turrilites cate-
natus. The lower figure rep-
resents the entire shell ; the
upper figure represents the
base of the shell seen from
below. Gault.

Fig. 20-t. — a, Ptychoceraa Emericianum, reduced
—Lower Greensand ; 6, Baculites anceps, reduced
—Chalk ; c, Portion of the same, showing the folded
edges of the septa ; d, Crioceras crittatum, reduced
—Gault ; e, Scaphite* cequalis, natural size — Chalk ;
/, Hamites rotundus, restored. — Gault.

of the Ammonitidce, to the Orthoceras in the series of the Nau-
tilidce. All the above-mentioned genera are characteristically,
or exclusively, Cretaceous, and they are accompanied by a

THE CRETACEOUS PERIOD. 283

number of other allied forms, which cannot be noticed here.
Not a single one of these genera, further, has hitherto been
detected in any strata higher than the Cretaceous. We may
therefore consider that these wonderful, varied, and elaborate
forms of Ammonitidce constitute one of the most conspicuous
features in the life of the Chalk period.

The Dibranchiate Cephalopods are represented partly by the
beak-like jaws of unknown species of Cuttle-fishes and partly
by the internal skeletons of Belemnites. Amongst the latter,
the genus Belemnites itself holds its place in the lower part of
the Cretaceous series; but it disappears in the upper portion
of the series, and its place is taken by the nearly-allied genus
Belemnitella (fig. 205), distinguished by the possession of a
straight fissure in the upper end of the guard. This
also disappears at the close of the Cretaceous
period; and no member of the great Mesozoic
family of the Belemnitidcs has hitherto been dis-
covered in any Tertiary deposit, or is known to
exist at the present day.

Passing on next to the Vertebrate Animals oi the
Cretaceous period, we find the Fishes represented
as before by the Ganoids and the Placoids, to which,
however, we can now add the first known examples
of the great group of the Bony Fishes or Teleosteans,
comprising the great majority of existing forms.
The Ganoid Fishes of the Cretaceous (Lepidotus,
Pycnodus, &c.) present no features of special in-
terest. Little, also, need be said about the Placoid
fishes of this period. As in the Jurassic deposits, Fig. 205.—
the remains of these consist partly of the teeth of 2»JS«Ha mu-

genuine Sharks (Lamna,Odontaspis, &c.),and partly
of the teeth and defensive spines of Cestracionts,
such as the living Port-Jackson Shark. The pointed and sharp-
edged teeth of true Sharks are very abundant in some beds, such
as the Upper Greensand, and are beautifully preserved. The
teeth of some forms (Carcharias, &c.) attain occasionally a
length of thr >e or four inches, and indicate the existence in the
Cretaceous seas of huge predaceous fishes, probably larger than
any existing Sharks. The remains of Cestracionts consist
partly of the flattened teeth of genera such as Acrodus and
Ptychodus (the latter confined to rocks of this age), and partly
of the pointed teeth of Hybodus, a genus which dates from the
Trias. In this genus the teeth (fig. 206) consist of a principal

284 HISTORICAL PALAEONTOLOGY.

central cone, flanked by minor lateral cones; and the fin-
spines (fig. 207) are longitudinally grooved, and carry a series
of small spines on their hinder or concave margin. Lastly,
the great modern order of the Bony Fishes or Teleosteans

Fig. 206.— Tooth
of Hybodus.

Fig. 207.— Fin-spine of Hybodus. Lower Greensand.

makes its first appearance in the Upper Cretaceous rocks,
where it is represented by forms belonging to no less than
three existing groups — namely, the Salmon family (Sal-
monidce), the Herring family (Clupeidce}, and the Perch family
(Percida). All these fishes have thin, horny, overlapping
scales, symmetrical (" homocercal ") tails, and bony skeletons.

Fig. 208.— 1, Beryx Lewesiensts, a Percoid fish from the Chalk ; 2, Osmeroides
Mantelli, a Salmonoid fish from the Chalk.

The genus Beryx (fig. 208, i) is one represented by existing
species at the present day, and belongs to the Perch family.

THE CRETACEOUS PERIOD. 285

The genus Osmeroides, again (fig. 208, 2), is supposed to be
related to the living Smelts (Osmerus), and, therefore, to
belong to the Salmon tribe.

No remains of Amphibians have hitherto been detected in
any part of the Cretaceous series; but Reptiles are extremely
numerous, and belong to very varied types. As regards the
great extinct groups of Reptiles which characterize the Meso-
zoic period as a whole, the huge " Enaliosaurs " or " Sea-
Lizards " are still represented by the Ichthyosaur and the
Plesiosaur. Nearly allied to the latter of these is the Elas-
mosaurus of the American Cretaceous, which combined the
long tail of the Ichthyosaur with the long neck of the Plesio-
saur. The length of this monstrous Reptile could not have
been less than fifty feet, the neck consisting of over sixty
vertebrae and measuring over twenty feet in length. The
extraordinary Flying Reptiles of the Jurassic are likewise well
represented in the Cretaceous rocks by species of the genus
Pterodactylus itself, and these later forms are much more
gigantic in their dimensions than their predecessors. Thus
some of the Cretaceous Pterosaurs seem to have had a spread
of wing of from twenty to forty-five feet, more than realizing
the " Dragons " of fable in point of size. The most remark-
able, however, of the Cretaceous Pterosaurs are the forms
which have recently been described by Professor Marsh under
the generic title of Pteranodon. In these singular forms — so
far only known as American — the animal possessed a skeleton
in all respects similar to that of the typical Pterodactyles,
except that the jaws are completely destitute of teeth. There
is, therefore, the strongest probability that the jaws were
encased in a horny sheath, thus coming to resemble the beak
of a Bird. Some of the recognized species of Pteranodon are
very small ; but the skull of one species (P. longiceps} is not
less than a yard in length, and there are portions of the skull
of another species which would indicate a length of four feet
for the cranium. These measurements would point to dimen-
sions larger than those of any other known Pterosaurs.

The great Mesozoic order of the Deinosaurs is largely rep-
resented in the Cretaceous rocks, partly by genera which
previously existed in the Jurassic period, and partly by entirely
new types. The great delta-deposit of the Wealden, in the
Old World, has yielded the remains of various of these huge
terrestrial Reptiles, and very many others have been found in
the Cretaceous deposits of North America. One of the most

286 HISTORICAL PALEONTOLOGY.

celebrated of the Cretaceous Deinosaurs is the Iguanodon, so
called from the curious resemblance of its teeth to those of the
existing but comparatively diminutive Iguana. The teeth (fig.
209) are soldered to the inner face of the jaw, instead of being
sunk in distinct sockets ; and they have the form of somewhat
flattened prisms, longitudinally ridged on the outer surface,
with an obtusely triangular crown, and having the enamel
crenated on one or both sides. They present the extraordinary
feature that the crowns became worn down flat by mastication,
showing that the Iguanodon employed its teeth in actually
chewing and triturating the vegetable matter on which it fed.
There can therefore be no doubt but that the Iguanodon, in
spite of its immense bulk, was an herbivorous Reptile, and
lived principally on the foliage of the Cretaceous forests
amongst which it dwelt. Its size has been variously estimated
at from thirty to fifty feet, the thigh-bone in large examples

Fig. 209.— Teeth of Iguanodon Mantellii. Wealden, Britain.

measuring nearly five feet in length, with a circumference of
twenty-two inches in its smallest part. With the strong and
massive hind-limbs are associated comparatively weak and
small fore-limbs; and there seems little reason to doubt that
the Iguanodon must have walked temporarily or permanently

THE CRETACEOUS PERIOD. 287

upon its hind-limbs, after the manner of a Bird. This conjec-
ture is further supported by the occurrence in the strata which
contain the bones of the Iguanodon of gigantic three-toed foot-
prints, disposed singly in a double track. These prints have
undoubtedly been produced by some animal walking on two
legs; and they can hardly, with any probability, be ascribed to
any other than this enormous Reptile. Closely allied to the

Fig. 210.— Skull of Mosasaurua Camperi, greatly reduced. Maestrlcht Chalk.

Iguanodon is the Hadrosaurus of the American Cretaceous, the
length of which is estimated at twenty-eight feet. Iguanodon
does not appear to have possessed any integumentary skeleton ;
but the great Hyl&osaurus of the Wealden seems to have been
furnished with a longitudinal crest of large spines running
down the back, similar to that which is found in the compara-
tively small Iguanas of the present day. The Megalosaurus of
the Oolites continued to exist in the Cretaceous period; and, as
we have previously seen, it was carnivorous in its habits. The
American Lalaps was also carnivorous, and, like the Megalosaur,
which it very closely resembles, appears to have walked upon
its hind-legs, the fore-limbs being disproportionately small.

Another remarkable group of Reptiles, exclusively confined
to the Cretaceous series, is that of the Mosasauroids, so called

288 HISTORICAL PALEONTOLOGY.

from the type-genus Mosasaurus. The first species of Mosa-
saurus known to science was the M. Camperi (fig. 210), the
skull of which — six feet in length — was discovered in 1780 in
the Maestricht Chalk at Maestricht. As this town stands on
the river Meuse, the name of Mosasaurus (" Lizard of the
Meuse") was applied to this immense Reptile. Of late years
the remains of a large number of Reptiles more or less closely
related to Mosasaurus, or absolutely belonging to it have been
discovered in the Cretaceous deposits of North America, and
have been described by Professors Cope ami Marsh. All
the known forms of this group appear to have been of large
size — one of them, Mosasaurus prince ps, attaining the length of
seventy-five or eighty feet, and thus rivalling the largest of ex-
isting Whales in its dimensions. The teeth in the " Mosa-
sauroids " are long, pointed, and slightly curved; and instead
of being sunk in distinct sockets, they are firmly amalgamated
with the jaws, as in modern Lizards. The palate also carried
teeth, and the lower jaw was so constructed as to allow of the
mouth being opened* to an immense width, somewhat as in the
living Serpents. The body was long and snake-like, with a
very long tail, which is laterally compressed, and must have
served as a powerful swimming-apparatus. In addition to this,
both pairs of limbs have the bones connecting them with the
trunk greatly shortened; whilst the digits were enclosed in the
integuments, and constituted paddles, closely resembling (in
structure the " flippers " of Whales and Dolphins. The neck
is sometimes moderately long, but oftener very short, as the
great size and weight of the head would have led one to antic-
ipate. Bony plates seem in some species to have formed an
at any rate partial covering to the skin; but it is not certain
that these integumentary appendages were present in all. Up-
on the whole, there can be no doubt but that the Mosasauroid
Reptiles — the true " Sea-serpents " of the Cretaceous period —
were essentially aquatic in their habits, frequenting the sea,
and only occasionally coming to the land.

The " Mosasauroids " have ger.crr'.ly been regarded as a
greatly modified group of the Lizards (Lacertilia'). Whether
this reference be correct or not — and recent investigations
render it dubious — the Cretaceous rocks have yielded the
remains of small Lizards not widely removed from existing

THE CRETACEOUS PERIOD.

forms. The recent order of the Chelonians is also represented

in the Cretaceous rocks,
by forms closely re-
sembling living types.
Thus the fresh-water
deposits of the Wealden
have yielded examples
of the " Terrapins " or
"Mud-Turtles" (Emys) ;
and the marine Creta-
ceous strata have been
found to contain the
remains of various spe-
cies of Turtles, one of
which is here figured
(fig. 211 ). No true
Serpents (Ophidia) have
as yet been detected in
the Cretaceous -rocks;
and this order does not
appear to have come
into existence till the
Tertiary period. Last-
ly, true Crocodiles are
known to have existed
in considerable num-
bers in the Cretaceous period. The oldest of these occur
in the fresh-water deposits of the Wealden ; and they differ from
the existing forms of the group in the fact that the bodies
of the vertebrae, like those of the Jurassic Crocodiles, are
bi-concave, or hollowed out at both ends. In the Greensand
of North America, however, occur the remains of Crocodiles
which agree with all the living species in having the bodies of
the vertebrae in the region of the back hollowed out in front
and convex behind.

Birds have not hitherto been shown, with certainty, to have
existed in Europe during the Cretaceous period, except in a
few instances in which fragmentary remains belonging to this
class have been discovered. The Cretaceous deposits of
North America have, however, been shown by Professor
Marsh to contain a considerable number of the remains of
Birds, often in a state of excellent preservation. Some of
these belong to swimming or Wading Birds, differing in no
19

Fig. 211.— Carapace of Chelone Benatedi.
Lower Chalk . ( After Owen . )

2QO HISTORICAL PALEONTOLOGY.

point of special interest from modern birds of similar habits.
Others, however, exhibit such extraordinary peculiarities that
they merit more than a passing notice. One of the forms in
question constitutes the genus Ichthyornis of Marsh, the type
species of which (7. disbar} was about as large as a Pigeon.
In two remarkable respects, this singular Bird differs from all
known living members of the class. One of these respects
concerns the jaws, both of which exhibit the Reptilian char-
acter of being armed with numerous small pointed teeth (fig.
212, a), sunk in distinct sockets. No existing bird possesses
teeth; and this character forcibly recalls the Bird-like Ptero-
saurs, with their toothed jaws. Ichthyornis, however, possessed
fore-limbs constructed strictly on the type of the " wing " of the
living Birds; and it cannot, therefore, be separated from this
class. Another extraordinary peculiarity of Ichthyornis is, that
the bodies of the vertebra (fig. 213, c} were bi-concave, as is the
case with many extinct Reptiles and almost all Fishes, but as
does not occur in any living Bird. There can be little doubt
that Iththyornis was aquatic in its habits, and that it lived prin-
cipally upon fishes ; but its powerful wings at the same time
indicate that it was capable of prolonged flight. The tail of
Ichthyornis has, unfortunately, not been discovered; and it is
at present impossible to say whether this resembled the tail of
existing Birds, or whether it was elongated and composed of
separate vertebrae, as in the Jurassic Arcliceopteryx.

Still more wonderful than Ichthyornis is the marvellous bird
described by Marsh under the name of Hesperornis regalis.
This, presents us with a gigantic diving bird, somewhat re-
sembling the existing "Loons" (Colymbus}, but agreeing
with Ichthyornis in having the jaws furnished with conical,
recurved, pointed teeth (fig. 212, fr). Hence these forms are
grouped together in a new sub-class, under the name of Odon-
'tornithes or "Toothed Birds." The teeth of Hesperornis (fig.
212, d~) resemble those of Ichthyornis in their general form;
but instead of being sunk in distant sockets, they are simply
implanted in a deep continuous groove in the bony substance
of the jaw. The front of the upper jaw does not carry teeth,
and was probably encased in a horny beak. The breast-bone
is entirely destitute of a central ridge or keel, and the wings
are minute and quite rudimentary; so that Hesperornis, unlike
Ichthyornis, must have been wholly deprived of the power of
flight, in this respect approaching the existing Penguins. The
tail consists of about twelve vertebrae, of which the last three or

THE CRETACEOUS PERIOD.

291

four are amalgamated to form a flat terminal mass, there being
at the same time clear indications that the tail was capable
of up and down movement in a vertical plane, this prob-
ably fitting it to serve as a swimming-paddle or rudder. The
legs were powerfully constructed, and the feet were adapted to
assist the bird in rapid motion through the water. The known
remains of Hesperornis regalis prove it to have been a swim-
ming and diving bird, of larger dimensions than any of the
aquatic members of the class of Birds with which we are ac-
quainted at the present day. It appears to have stood between
five and six feet high, and its inability to fly is fully compen-
sated for by the numerous adaptations of its structure to a

Fig. 212.— Toothed Birds (Odontornithes} of the Cretaceous Rocks of America, a,
Left lower jaw of Ichlhyornis dispar, slisrhtly enlarged ; ft, Left lower jaw of Hesperor-
nia regalis, reduced to nearly one-fourth of the natural size ; c. Cervical vertebra of
Ir/itiii/ornis dispar, front view, twice the natural size ; c'. Side view of the same ; d,
Tooth of Hesperornis regalia, enlarged to twice the natural size. (After Marsh.)

watery life. Its teeth prove it to have been carnivorous in its
habits, and it probably lived upon fishes. It is a curious fact
that two Birds agreeing with one another in the wholly abnor-
mal character of possessing teeth, and in other respects so
entirely different, should, like IchtJiyornis and Hesperornis,
have lived not only in the some geological period, but also in
the same geographical area; and it is equally curious that
the area inhabited by these toothed Birds should at the same

2Q2 HISTORICAL PALEONTOLOGY.

time have been tenanted by winged and bird-like Reptiles
belonging to the toothed genus Pterodactylus and the toothless
genus Pteranodon.

No remains of Mammals, finally, have as yet been detected
in any sedimentary accumulation of Cretaceous age.

LITERATURE.

The following list comprises of the more important works and
memoirs which may be consulted with reference to the Creta-
ceous strata and their fossil contents : —

1 i ) ' Memoirs of the Geological Survey of Great Britain. '

(2) ' Geology of England and Wales. ' Conybeare and Phil-

lips.

(3) 'Geology of Yorkshire,' vol. ii. Phillips.

(4) 'Geology of Oxford and the Thames Valley.' Phillips.

(5) 'Geological Excursions through the Isle of Wight.' Man-

tell.

(6) ' Geology of Sussex. ' Mantell.

(7) ' Report on Londonderry, ' &c. Portlock.

(8) ' Recherches sur le Terrain Cretace Superieur de 1'Ang-
leterre et de 1'Irlande. ' Barrois.

(9) "Geological Survey of Canada" — 'Report of Progress,

1872-73. '

(10) 'Geological Survey of California.' Whitney.

(n) 'Geological Survey of Montana, Idaho, Wyoming, and
Utah. ' Hayden and Meek.

(12) 'Report on Geology,' &c. (British North America

Boundary Commission). G. M. Dawson.

(13) 'Manual of Geology.' Dana.

(14) 'Lethaea Rossica. ' Eichwald.

(15) ' Petrefacta Germanise. ' Goldfuss.

(16) 'Fossils of the South Downs.' Mantell.

(17) 'Medals of Creation.' Mantell.

(18) ' Mineral Conchology. ' Sowerby.

(19) 'Lethaea Geognostica. ' Bronn.

(20) ' Malacostracous Crustacea of the British Cretaceous

Formation' ( Paheontographical Society). Bell.

(21) ' Brachiopoda of the Cretaceous Formation' Palseon-

tographical Society). Davidson.

(22) 'Corals of the Cretaceous Formation' ( Palaeontograph-
ical Society). Milne-Edwards and Haime.

THE CRETACEOUS PERIOD. 293

(23) * Supplement to the Fossil Corals' (Palaeontographical

Society). Martin Duncan.

(24) ' Echinodermata of the Cretaceous Formation' (Palaeon-

tographical Society). Wright.

(25) 'Monograph of the Belemnitidae ' (Pakeontographical

Society). Phillips.

(26) 'Monograph of the Trigoniae' (Palaeontographical So-
ciety). Lycett.

(27) 'Fossil Cirripedes ' (Palaeontographical Society). Darwin.

(28) 'Fossil Mollusca of the Chalk of Britain' (Palaeonto-
graphical Society). Sharpe.

(29) ' Entomostraca of the Cretaceous Formation' (Palaeon-

tographical Society). Rupert Jones.

(30) ' Monograph of the Fossil Reptiles of the Cretaceous

Formation' (Palaeontographical Society). Owen.

(31) 'Manual of Palaeontology.' Owen.

(32) ' Synopsis of Extinct Batrachia and Reptilia. ' Cope.
(33} " Structure of the Skull and Limbs in Mosasauroid

Reptiles " — ' American Journ. Sci. and Arts, 1872.' Marsh.

(34) " On Odontornithes " — ' American Journ. Sci. and Arts,

1875. ' Marsh.

(35) * Ossemens Fossiles. ' Cuvier.

(36) ' Catalogue of Ornithosauria. ' Seeley.

(37) ' Paleontologie Frangaise. ' D'Orbigny.

(38) ' Synopsis des Echinides fossiles. ' Desor.

(39) ' Cat. Raisonne des Echinides. ' Agassiz and Desor.

(40) " Echinoids " — ' Decades of the Geol. Survey of Britain. '

E. Forbes.

(41) 'Paleontologie Franchise. ' Cotteau.

(42) ' Versteinerungen der Bohmischen Kreide-formation. '

Reuss.

(43)" Cephalopoda, Gasteropoda, Pelecypoda, Brachiopoda,
&c., of the Cretaceous Rocks of India " — ' Palaeonto-
logica Indica, ' ser. i., iii., v., vi., viii. Stoliczka.

(44) " Cretaceous Reptiles of the United States "— ' Smith-

sonian Contributions to Knowledge,' vol. xiv. Leidy.

(45) ' Invertebrate Cretaceous, and Tertiary Fossils of the

Upper Missouri Country. ' 1876. Meek.

294 HISTORICAL PALAEONTOLOGY.

/

CHAPTER XVIII.
THE EOCENE PERIOD.

Before commencing the study of the subdivisions of the
Kainozoic series, there are some general considerations to be
noted. In the first place, there is in the Old World a com-
plete and entire physical break between the rocks of the
Mesozoic and Kainozoic periods. In no instance in Europe
are Tertiary strata to be found resting conformably upon any
Secondary rock. The Chalk has invariably suffered much
erosion and denudation before the lowest Tertiary strata were
deposited upon it. This is shown by the fact that the actually^
eroded surface of the Chalk can often be seen; or, failing this,
that we can point to the presence of the chalk-flints in the
Tertiary strata. This last, of course, affords unquestionable
proof that the Chalk must have been subjected to enormous
denudation prior to the formation of the Tertiary beds, all the
chalk itself having been removed, and nothing left but the
flints, while these are all rolled and rounded. In the continent
of North America, on the other hand, the lowest Tertiary strata
have been shown to graduate downwards conformably with the
highest Cretaceous beds, it being a matter of difficulty to draw
a precise line of demarcation between the two formations.

In the second place, there is a marked break in the life of
the Mesozoic and Kainozoic periods. With the exception of
a few Foraminifera, and one Brachiopod (the latter doubtful),
no Cretaceous species is known to have survived the Creta-
ceous period; while several characteristic families, such as the
Ammonitida ', Belemnitida, and Hippuritida, died out entirely
with the close of the Cretaceous rocks. In the Tertiary rocks,
on the other hand, not only are all the animals and plants
more or less like existing types, but we meet with a constantly-
increasing number of living species as we pass from the bottom
of the Kainozoic series to the top. Upon this last fact is
founded the modern classification of the Kainozoic rocks,
propounded by Sir Charles Lyell.

The absence in strata of Tertiary age of the chambered
Cephalopods, the Belemnites, the Hippurites, the Inocerami,
and the diversified types of Reptiles which form such con-

THE EOCENE PERIOD. 295

spicuous features in the Cretaceous fauna, render the palseon-
tological break between the Chalk and the Eocene one far too
serious to be overlooked. At the same time, it is to be re-
membered that the evidence afforded by the explorations car-
ried out of late years as to the animal life of the deep sea, ren-
ders it certain that the extinction of marine forms of life at the
close of the Cretaceous period was far less extensive than had
been previously assumed. It is tolerably certain, in fact, that
we may look upon some of the inhabitants of the depths of our
existing oceans as the direct, if modified, descendants of ani-*
mals which were in existence when the Chalk was deposited.

It follows from the general want of conformity between the
Cretaceous and Tertiary rocks, and still more from the great
difference in life, that the Cretaceous and Tertiary periods are
separated, in the Old World at any rate, by an enormous lapse
of unrepresented time. How long this interval may have been,
we have no means of judging exactly, but it very possibly was
as long as the whole Kainozoic epoch itself. Some day we
shall doubtless find, at some part of the earth's surface, marine
strata which were deposited during this period, and which will
contain fossils intermediate in character between the organic
remains which respectively characterize the Secondary and
Tertiary periods. At present, we have only slight traces of
such deposits — as, for instance, the Maestricht beds, the Faxoe
Limestone, and the Pisolitic Limestone of France.

CLASSIFICATION OF THE TERTIARY ROCKS. — The classifica-
tion of the Tertiary rocks is a matter of unusual difficulty, in
consequence of their occurring in disconnected basins, form-
ing a series of detached areas, which hold no relations of
superposition to one another. The order, therefore, of the
Tertiaries in point of time, can only be determined by an ap-
peal to fossils; and in such determination Sir Charles Lyell
proposed to take as the basis of classification the proportion of
living or existing species of Mollusca which occurs in each stra-
tum or group of strata. Acting upon this principle, Sir Charles
Lyell divides the Tertiary series into four groups : —

I. The Eocene formation (Gr. eos, dawn; kainos, new), con-
taining the smallest proportion of existing species, and being,
therefore, the oldest division. In this classification, only the
Mollusca are taken into account; and it was found that of
these about three and a half per cent were identical with ex-
isting species.

296 HISTORICAL PALAEONTOLOGY.

II. The Miocene formation (Gr. melon, less; kainos, new),
with more recent species than the Eocene, but less than the suc-
ceeding formation, and less than one-half the total number in the
formation. As before, only the Mollusca are taken into account,
and about 17 per cent of these agree with existing species.

III. The Pliocene formation (Gr. Pleion, more; kainos, new)
with generally more than half the species of shells identical with
existing species — the proportion of these varying frora 35 to
50 per cent in the lower beds of this division, up to 90 or 95
per cent in its higher portion.

IV. The Post-Tertiary Formations, in which all the shells
belong to existing species. This, in turn, is divided into two
minor groups — the Post-Pliocene and Recent Formations. In
the Post-PUncene formations, while all the Mollusca belong to
existing species, most of the Mammals belong to extinct
species. In the Recent period, the quadrupeds, as well as the
shells, belong to living species.

The above, with some modifications, was the original classi-
fication proposed by Sir Charles Lyell for the Tertiary rocks,
and now universally accepted. More recent researches, it is
true, have somewhat altered the proportions of existing species
to extinct, as stated above. The general principle, however,
of an increase in the number of living species, still holds good ;
and this is as yet the only satisfactory basis upon which it has
been proposed to arrange the Tertiary deposits.

EOCENE FORMATION.

The Eocene rocks are the lowest of the Tertiary series, and
comprise all those Tertiary deposits in which there is only a
small proportion of existing Mollusca — from three and a half
to five per cent. The Eocene rocks occur in several basins in
Britain, France, the Netherlands, and other parts of Europe,
and in the United States. The subdivisions which have been
established are extremely numerous, and it is often impossible
to parallel those of one basin with those of another. It will
be sufficient, therefore, to accept the division of' the Eocene
formation into three great groups — Lower, Middle, and Upper

THE EOCENE PERIOD. 297

Eocene — and to consider some of the more important beds
comprised under these heads in Europe and in North America.

I. EOCENE OF BRITAIN. (i.) LOWER EOCENE. — The base
of the Eocene series in Britain is constituted by about 90 feet
of light-colored, sometimes argillaceous sands (Thanet Sands),
which are of marine origin. Above these, or forming the base
of the formation where these are wanting, come mottled clays
and sands with lignite (Woolwich and Reading series'), which
are estuarine or fluvio-marine in origin. The highest member
of the Lower Eocene of Britain is the " London Clay, " consist-
ing of a great mass of dark-brown or blue clay, sometimes with
sandy beds, or with layers of " septaria, " the whole attaining a
thickness of from 200 to as much as 500 feet. The London
Clay is a purely marine deposit, containing many marine fossils,
with the remains of terrestrial animals and plants; all of which
indicate a high temperature of the sea and tropical or sub-
tropical condition of the land.

(2.) MIDDLE EOCENE. — The inferior portion of the Middle
Eocene of Britain consists of marine beds, chiefly consisting
of sand, clays, and gravels, and attaining a very considerable
thickness (Bagshot and Bracklesham beds). The superior por-
tion of the Middle Eocene of Britain, on the other hand, con-
sists of deposits which are almost exclusively fresh-water or
brackish-water in origin (Headon and Osborne series).

The chief Continental formations of Middle Eocene age are
the " Calcaire grossier " of the Paris basin, and the " Num-
mulitic Limestone" of the Alps.

(3.) UPPER EOCENE. — If the Headon and Osborne beds of
the Isle of Wight be placed in the Middle Eocene, the only
British representatives of the upper Eocene are the Bembridge
beds. These strata consist of limestones, clays, and marls,
which have for the most part been deposited in fresh or brack-
ish water.

II. EOCENE BEDS OF THE PARIS BASIN. — The Eocene
strata are very well developed in the neighborhood of Paris,
where they occupy a large area or basin scooped out of the
Chalk. The beds of this area are partly marine, partly fresh-
water in origin ; and the following table (after Sir Charles
Lyell) shows their subdivisions and their parallelism with the
English series: —

2o8 HISTORICAL PALEONTOLOGY.

GENERAL TABLE OF FRENCH EOCENE STRATA.
UPPER EOCENE.

French Subdivisions. English Equivalents.

A. i. Gypseous series of I. Bembridge series.

Montmatre.
A, 2. Calcaire silicieux, or 2. Osborne and Headon series.

Travertin Inferieur.

A. 3. Gres de Beauchamp, or 3. White sand and clay of

Sables Moyens. Barton Cliff, Hants.

MIDDLE EOCENE.

B. I. Calcaire Grossier. i. Bagshot and Bracklesham

B. 2. Soissonnais Sands, or beds.

Lits Coquilliers. 2. Wanting.

LOWER EOCENE.

C. i. Argile de Londres at i. London clay.

base of Hill of Cassel,

near Dunkirk.
C. 2. Argile plastique and lig- 2. Plastic clay and sand with

nite. lignite (Woolwich

and Reading series).
C. 3. Sables de Bracheux. 3. Thanet sands.

III. EOCENE STRATA OF THE UNITED STATES. — The low-
est member of the Eocene deposits of North America^ is the
so-called " Lignitic Formation," which is largely developed in
Mississippi, Tennessee, Arkansas, Wyoming, Utah, Colorado,
and California, and sometimes attain a thickness of several
thousand feet. Stratigraphically, this formation exhibits the
interesting point that it graduates downwards insensibly and
conformably into the Cretaceous, whilst it is succeeded uncon-
formably by strata of Middle Eocene age. Lithologically, the
series -consists principally of sands and clays, with beds of lig-
nite and coal, and its organic remains show that it is principally
of fresh-water origin with a partial intermixture of marine beds.
These marine strata of the " Lignitic formation '; are of special
interest, as showing such a commingling of Cretaceous and
Tertiary types of life, that it is impossible to draw any rigid
line in this region between the Mesozoic and Kainozoic sys-
tems. Thus the marine beds of the Lignitic series contain
such characteristic Cretaceous forms as Inoceramus and Am-

THE EOCENE PERIOD. 299

monites, along with a great number of Univalves of a distinctly
Tertiary type (Cones, Cowries, &c.) Upon the whole, there-
fore, we must regard this series of deposits as affording a kind
of transition between the Cretaceous and the Eocene, holding
in some respects a position which may be compared with that
held by the Purbeck beds in Britain as regards the Jurassic
and Cretaceous.

The Middle Eocene of the United States is represented
by the Claiborne and Jackson beds. The Claiborne series is
extensively developed at Claiborne, Alabama, and consists of
sands, clays, lignites, marls, and impure limestones, containing
marine fossils along with numerous plant-remains. The Jack-
son series is represented by lignitic clays and marls which occur
at Jackson, Mississippi. Amongst the more remarkable fossils
of this series are -the teeth and bones of Cretaceans of the
genus Zeuglodon.

Strata of Upper Eocene age occur in North America at
Vicksburg, Mississippi, and are known as the Vicksburg series.
They consist of lignites, clays, marls, and limestones. Fresh-
water deposits of Eocene age are also largely developed in
parts of the Rocky Mountain region. The most remarkable
fossils of these beds are Mammals, of which a large number of
species have been already determined.

LIFE OF THE EOCENE PERIOD.

The fossils of the Eocene deposits are so numerous that
nothing more can be attempted here than to give a brief and
general sketch of the life of the period, special attention being
directed to some of the more prominent and interesting types,
amongst which — as throughout the Tertiary series — the Mam-
mals hold the first place. It is not uncommon, indeed, to
speak of the Tertiary period as a whole under the name of the
"Age of Mammals, " a title at least as well deserved as that of
" Age of Reptiles " applied to the Mesozoic, or " Age of Mol-
luscs " applied to the Palaeozoic epoch.

As regards the plants of the Eocene, the chief point to be
noticed is, that the conditions which had already set in with
the commencement of the Upper Cretaceous, are here con-
tinued, and still further enforced. The Cycads of the Secondary
period, if they have not totally disappeared, are exceedingly
rare; and the Conifers, losing the predominance which they

300

HISTORICAL PALAEONTOLOGY.

enjoyed in the Mesozoic, are now relegated to a subordinate
though well-defined place in the terrestrial vegetation. The
great majority of the Eocene plants are referable to the groups
of the Angiospermous Exogens and the Monocotyledons ; and
the vegetation of the period, upon the whole, approximates
closely to that now existing upon the earth. The plants of the
European Eocene are, however, in the main most closely allied
to forms which are now characteristic of tropical or sub-tropical
regions. Thus, in the London Clay are found numerous fruits
of Palms (Nipadites, fig. 213), along with various other plants,
most of which indicate a warm climate
as prevailing in the south of England
at the commencement of the Eocene
period. In the Eocene strata of North
America occur numerous plants belong-
ing to existing types — such as Palms,
Conifers, the Magnolia, Cinnamon, Fig,
Dog-wood, Maple, Hickory, Poplar,
Plane, &c. Taken as a whole, the
Eocene flora of North America is nearly
related to that of the Miocene strata of
Europe, as well as that now existing
in the American area. We may con-
clude, therefore, that " the forests of
the American Eocene resembled those

of the European Miocene, and even of modern America"
(Dana).

As regards the animals of the Eocene period, the Protozoans
are represented by numerous Foraminifera, which reach here
their maximum of development, "both as regards the size of
individuals and the number of generic types. Many of the
Eocene Foraminif ers are of small size ; but even these not
uncommonly form whole rock-masses. Thus, the so-called
" Miliolite Limestone " of the Paris basin, largely used as a
building-stone, is almost wholly composed of the shells of a
small species of Miliola. The most remarkable, however, of
the many members of this group of animals which flourish in
Eocene times, are the " Nummulites " (Nummulina), so called
from their resemblance in shape to coins (Lat. nummus, a coin).
The Nummulites are amongst the largest of all known Fora-
minifera, sometimes attaining a size of three inches in circum-
ference; and their internal structure is very complex (fig. 214).
Many species are known, and they are particularly character-

Fig. 213.— Nipadites ellipti-
cu8, the fruit of a fossil Palm.
London Clay, Isle of Sheppey.

THE EOCENE PERIOD.

301

istic of the Middle and Upper of these periods — their place
being sometimes taken by Orbitoides, a form very similar to the
Nummulite in external appearance, but differing in its internal
details. In the Middle Eocene, the remains of Nummulites
are found in vast numbers in very widely-spread and easily-
recognized formation known as the " Nummulitic Limestone "
(fig. 10). According to Sir Charles Lyell, "the Nummulitic
Limestone of the Swiss Alps rises to more than 10,000 feet
above the level of the sea, and attains here and in other moun-
tain-chains a thickness of several thousand feet. It may be
said to play a far more conspicuous part than any other Tertiary
group in the solid framework of the earth's crust, whether in
Europe, Asia, or Africa. It occurs in Algeria and Morocco,
and has been traced from Egypt, where it was largely quarried
of old for the building of the Pyramids, into Asia Minor, and
across Persia by Bagdad to the mouths of the Indus. It has
been observed not only in Cutch, but in the mountain-ranges

Fig. 214. — Nummulina lotvigata. Middle Eocene.

which separate Scinde from Persia, and which form the passes
leading to Cabul ; and it has been followed still further east-
ward into India, as far as Eastern Bengal and the frontiers of
China. " The shells of Nummulites have been found at an
elevation of 16,500 feet above the level of the -sea in Western
Thibet; and the distinguished and philosophical geologist just
quoted, further remarks, that " when we have once arrived at
the conviction that the Nummulitic formation occupies a mid-
dle and upper place in the Eocene series, we are struck with
the comparatively modern date to which some of the greatest
revolutions in the physical geography of Europe, Asia, and
Northern Africa must be referred. All the mountain-chains —
such as the Alps, Pyrenees, Carpathians, and Himalayas — into
the composition of whose central and loftiest parts the Num-
mulitic strata enter bodily, could have had no existence till

302

HISTORICAL PALAEONTOLOGY.

after the Middle Eocene period. During that period, the sea
prevailed where these chains now rise ; for Nummulites and
their accompanying Testacea were unquestionably inhabitants
of salt water. "

The Ccelcnterates of the Eocene are represented principally
by Corals, mostly of types identical with or nearly allied to
those now in existence. Perhaps the most characteristic group
of these is that of the Turbinolidcc, comprising a number of
simple "cup-corals, " which probably lived in moderately deep
water. One of the forms belonging to this family is here
figured (fig. 215). Besides true Corals, the Eocene deposits
have yielded the remains of the " Sea-
pens " (Pennatulida} and the branched
skeletons of the " Sea-shrubs " (Gorgonida}.

The Echinoderms are represented prin-
cipally by Sea-urchins, and demand nothing
more than mention. It is to be observed,
however, that the great group of the Sea-
lilies (Crinoids) is now verging on extinc-
tion, and is but very feebly represented.

Amongst the Mollusca, the Polyzoans
and Brachiopods also require no special men-
tion, beyond the fact that the latter are
greatly reduced in numbers, and belong
principally to the existing genera Tere-
bratula and Rhynchonella. The Bivalves
(Lamellibranchs) and the Univalves (Gas-
ieropods) are exceedingly numerous, and
almost all the principal existing genera are
now represented ; though less than five
per cent of the Eocene species are identical
with those now living. It is difficult to
make any selection from the many Bivalves
which are known in deposits of this age;
but species of Cardita, Crassatella, Leda,
Cyrena, Mactra, Cardium, Psammobia, &c.,
may be mentioned as very characteristic.
The Cardita planicosta here figured (fig.
216) is not only very abundant in the
Middle Eocene, but is very widely distrib-
uted, ranging from Europe to the Pacific coast of North
America. The Univalves . of the Eocene are extremely nu-
merous, and generally beautifully preserved. The majority

Fig. 2l5.—Turbinolia
aulcata. viewed from one
side, and from above.
Eocene.

THE EOCENE PERIOD.

303

of them belong to that great section of the Gasteropods in
which the mouth of the shell is notched or produced into
a canal (when the shell is said to be " siphonostomatous ") —
this section including the carnivorous and most highly-or-
ganized groups of the class. Not only is this the case, but
a large number of the Eocene Univalves belong to types
which now attain their maximum of development in the
warmer regions of the globe. Thus we find numerous species

Fig. 216. — Cardita planicosta. Middle Eocene.

of Cones (Conus}, Volutes (Valuta}, Cowries (Cyprcea, fig. 218),
Olives and Rice-shells (Olivd), Mitre-shells (Mltra}, Trumpet-
shells (Triton}, Auger-shells (Terebra), and Fig-shells (Pyrula).
Along with these are many forms of Pleurotoma, Rostellaria,
Spindle-shells (Fusus*), Dog- whelks (Nassa}, Murices, and many
round-mouthed ("holostomatous ") species, belonging to such

Fig. 217 .—Typhia tubifer, a " siphonosto-
matous ' ' Univalve . Eocene .

Fig. 218. Cyprcea
elegant. Eocene.

genera as Turritella, Nerita, Natica, Scalaria, &c. The genus
Cerithium (fig. 219), most of the living forms of which are

304

HISTORICAL PALEONTOLOGY.

found in warm regions, inhabiting fresh or brackish waters,
undergoes a vast development in the Eocene period, where it
is represented by an immense number of specific forms, some
of which attain very large dimensions. In the Eocene strata
of the Paris basin alone, nearly one hundred
and fifty species of this genus have been
detected. The more strictly fresh-water
deposits of the Eocene period have also
yielded numerous remains of Univalves such
as are now proper to rivers and lakes-, to-
gether with the shells of true Land-snails.
Amongst these may be mentioned numerous
species of Limncea (fig. 22o),Physa (fig. 221),
Melania, Paludina, Planorbis, Helix, Buli-
mus, and Cyclostoma (fig. 222).

With regard to the Cephalopods, the chief
point to be noticed is, that all the beautiful
and complex forms which peculiarly char-
acterized the Cretaceous period have here
disappeared. We no longer meet with a
single example of the Turrilite, the Baculite,
the Hamite, the Scaphite, or the Ammonite. The only ex-
ception to this statement is the occurrence of one species
of Ammonite in the so-called " Lignitic Formation " of North
America ; but the beds containing this may possibly be rather
referable to the Cretaceous — and this exception does not
affect the fact that the Ammonitida, as a family, had be-

Fig. 219. — Cerithi-
um hexagenum. Eo-
cene.

Fig. 220.— Limncea
pyramidalis.

Fig. Vll.—Physa
columnaris. Eocene.

Fig. 222.— Cyclostoma
Arnoudii. Eocene.

come extinct before the Eocene strata were deposited. The
ancient genus Nautilus still survives, the sole representative of
the once mighty order of the Tetrabranchiate Cephalopods.

THE EOCENE PERIOD. 305

In the order of the Dibranchiates, we have a like phenomenon
to observe in the total extinction of the great family of the
" Belemnites. " No form referable to this group has hitherto
been found in any Tertiary stratum; but the internal skeletons
of Cuttle-fishes (such as Belosepia} are not unknown.

Remains of Fishes are very abundant in strata of Eocene
age, especially in certain localities. The most famous depot
for the fossil fishes of this period is the limestone of Monte
Bolca, near Verona, which is interstratified with beds of vol-
canic ashes, the whole being referable to the Middle Eocene.
The fishes here seem to have been suddenly destroyed by a
volcanic eruption, and are found in vast numbers. Agassiz

Fig. 223.—Rh(nnbug minimus, a small fossil Turbot from the Eocene Tertiary,
Monte Boles.

has described over one hundred and thirty species of Fishes
from this locality, belonging to seventy-seven genera. All
the species are extinct; but about one-half of the genera are
represented by living forms. The great majority of the
Eocene Fishes belong to the order of the " Bony Fishes "
(Teleostcans}, so that in the main the forms of Fishes charac-
terizing the Eocene are similar to those which predominate
in existing seas. In addition to the above, a few Ganoids and
a large number of Placoids are known to occur in the Eocene
rocks. Amongst the latter are found numerous teeth of true
Sharks, such as Otodus (fig. 224) and Carcharodon. The
pointed and serrated teeth of the latter sometimes attain a
20

306

HISTORICAL PALEONTOLOGY.

length of over half a foot, indicating that these predaceous
fishes attained gigantic dimensions; and it is interesting to
note that teeth, in external appearance very similar to those
of the early Tertiary genus Carcharodon, have been dredged

Fig. 224.— Tooth of

Otodus obliquus,

Eocene.

Fig. 225.— Flattened dental plates of a Ray
(Myliobatia Edwardaii) . Eocene.

from great depths during the recent expedition of the Chal-
lenger. There also occur not uncommonly the flattened
teeth of Rays (fig. 225), consisting of flat bony pieces placed
close together, and forming " a kind of mosaic pavement on
both the upper and lower jaws." (Owen).

In the1 class of the Reptiles, the disappearance of the char-
acteristic Mesozoic types is as marked a phenomenon as the
introduction of new forms. The Ichthyosaurs, the Plesio-
saurs, the Pterosaurs, and the Mosasaurs of the Mesozoic,
find no representatives in the Eocene Tertiary ; and the same
is true of the Deinosaurs, if we except a few remains from the
doubtfully-situated "Lignitic formation" of the United States.
On the other hand, all the modern orders of Reptiles are
known to have existed during the Eocene period. The
Chelonians are represented by true marine Turtles, by "Ter-
rapins" (Emydida?}, and by "Soft Tortoises" (Trionycida).
The order of the Snakes and Serpents (Ophidia) makes its
appearance here for the first time under several forms — all of
which, however, are referable to the non-venomous group of
the "Constricting Serpents" (Boidce}. The oldest of these
is the Palceophis toliapicus of the London Clay of Sheppey,
first made known to science by the researches of Professor
Owen. The nearly-allied Palcuophis typh&us of the Eocene
beds of Bracklesham appears to have been a Boa-constrictor-
like Snake of about twenty feet in length. Similar Python-
like Snakes (Pal&ophis, Dinophis, &c.) have been described
from the Eocene deposits of the United States. True Lizards

THE EOCENE PERIOD. 307

(Lacertilians) are found in some abundance in the Eocene
deposits, — some being small terrestrial forms, like the common
European lizards of the present day ; whilst others equal or
exceed the living Monitors in size. Lastly, the modern ordei
of the Crocodilia is largely represented in Eocene times, by
species belonging to all the existing genera, together with
others referable to extinct types. As pointed out by Owen,
it is an interesting fact that in the Eocene rocks of the south-
west of England, there occur fossil remains of all the three
living types of Crocodilians — namely, the Gavials, the true
Crocodiles, and the Alligators (fig. 226) — though at the
present day these forms are all geographically restricted in
their range, and are never associated together.

Almost " all the existing orders of Birds, if not all, are
represented in the Eocene deposits by remains often very
closely allied to existing types. Thus, amongst the Swimming
Birds (Natatores) we find examples of forms allied to the
living Pelicans and Mergansers; amongst the Waders (Gral-
latores') we have birds resembling the Ibis (the Numenius
gypsorum of the Paris basin) ; amongst the Running Birds
(Cursores} we meet with the great Gastornis Parisiensis, which
equalled the African Ostrich in height, and the still more

Fig. 226. — Upper jaw fof Alligator. Eocene Tertiary. Isle of Wight.

gigantic Dasontis Londinensis; remains of a Partridge rep-
resent the Scratching Birds (Rasores) ; the American Eocene
has yielded the bones of one of the Climbing Birds (Scan-
sores), apparently referable to the Woodpeckers; the Protornis
Glarisiensis of the Eocene Schists of Claris is the oldest
known example of the Perching Birds (Insessores} ; and the

308 HISTORICAL PALEONTOLOGY.

Birds of Prey (Raptores} are represented by Vultures, Owls,
and Hawks. The toothed Birds of the Upper Cretaceous
are no longer known to exist ; but professor Owen has
recently described from the London Clay the skull of a very
remarkable Bird, in which there is, at any rate, an approxi-
mation to the structure of Ichthyornis and Hesperornis. The
bird in question has been named the Odontopteryx toliapicus,
its generic title being derived from the very remarkable char-
acters of its jaws. In this singular form (fig. 227) the margins
of both jaws are furnished with tooth-like denticulations, which
differ from true teeth in being actually portions of the bony

Fig. 227. — Skull of Odontopteryx toliapicus, restored. ( After Owen. )

substance of the jaw itself, with which they are continuous,
and which were probably encased by extensions of the horny
sheath of the bill. These tooth-like processes are of two
sizes, the larger ones being comparable to canines ; and they
are all directed forwards, and have a triangular or compressed
conical form. From a careful consideration of all the dis-
covered remains of this bird, Professor Ow-n concludes that
" Odontopteryx was a warm-blooded feathered biped, with
wings ; and further, that it was web-footed and a fish-eater,
and that in the catching of its slippery prey it was assisted by
this Pterosauroid armature of its jaws. " Upon the whole,
Odontopteryx would appear to be most nearly related to the
family of the Geese (Anserince) or Ducks (Anatidcu) ; but the
extension of the bony substance of the jaws into tooth-like
processes is an entirely unique character, in which it stands
quite alone.

The known Mammals of the Mesozoic period, as we have
seen, are all of small size ; and with one not unequivocal
exception, they appear to be referable to the order of the

THE EOCENE PERIOD. 309

Pouched Quadrupeds (Marsupials), almost the lowest group
of the whole class of the Mammalia. In the Eocene rocks,
on the other hand, numerous remains of Quadrupeds have
been brought to light, representing most of the great Mam-
malian orders now in existence upon the earth, and in many
cases indicating animals of very considerable dimensions. We
are, in fact, in a position to assert that the majority of the
great groups of Quadrupeds with which we are familar at the
present day were already in existence in the Eocene period,
and that their ancient root-stocks were even in this early time
separated by most of the fundamental differences of structure
which distinguish their living representatives. At the same
time, there are some amongst the Eocene quadrupeds which
have a " generalized " character, and which may be regarded
as structural types standing midway between groups now
sharply separated from one another.

The order of the Marsupials — including the existing Kan-
garoos, Wombats, Opossums, Phalangers, &c. — is poorly
represented in deposits of Eocene age. The most celebrated
example of this group is the Didelphys gypsorum of the
Gypseous beds of Montmartre, near Paris, an Opossum very
nearly allied to the living Opossums of North and South
America.

No member of the Edentates (Sloths, Ant-eaters, and Arma-
dillos) has hitherto been detected in any Eocene deposit.
The aquatic order of the Sirenians (Dugongs and Manatees),
with their fish-like bodies and tails, paddle-shaped fore-
limbs, and wholly deficient hind-limbs, are represented in
strata of this age by remains of the ancient " Sea-Cows, " to
which the name of Halitherium has been applied. Nearly
allied to the preceding is the likewise aquatic order of the
Whales and Dolphins (Cetaceans), in which the body is also
fish-like, the hind-limbs are wanting, the fore-limbs are con-
verted into powerful " flippers " or swimming-paddles, and
the terminal extremity of the body is furnished with a
horizontal tail-fin. Many existing Cetaceans (such as the
Whalebone Whales) have no true teeth; but others (Dol-
phins, Porpoises, Sperm Whales) possess simple conical teeth.
In strata of Eocene age, however, we find a singular group
of Whales constituting the genus Zeuglodon (fig. 228), in
which the teeth differed from those of all existing forms in
being of two kinds, — the front ones being conical incisors,
whilst the back teeth or molars have serrated triangular

3io HISTORICAL PALEONTOLOGY.

crowns, and are inserted in the jaw by two roots. Each
molar (fig. 228, A) looks as if it were composed of two
separate teeth united on the one side by their crowns; and it is
this peculiarity which is expressed by the generic name (Gr.
zeugle, a yoke; odous, tooth). The best-known species of
the genus is the Zeuglodon cetoides of Owen, which attained
a length of seventy feet. Remains of these gigantic Whales
are very common in the " Jackson Beds " of the Southern
United States. So common are they that, according to Dana,

Fig. 228.— Zeuglodon cetoides. A, Molar tooth of the natural size ; B, Vertebra,
reduced in size. From the Middle Eocene of the United States. (After Lyell.)

"the large vertebrae, some of them a foot and a half long and
a foot in diameter, were formerly so abundant over the
country, in Alabama, that they were used for making walls, or
were burned to rid the fields of them."

The great and important order of the Hoofed Quadrupeds
(Ungulata) is represented in the Eocene by examples of both
of its two principal sections — namely, those with an uneven
number of toes (one or three) on the foot (Perissodactyle Ungu-
lates), and those with an even number of toes (two or four) to
each foot (Artiodactyle Ungulates}. Amongst the Odd-toed
Ungulates, the living family of the Tapirs (Tapiridce) is repre-
sented by the genus Coryphodon of Owen. Nearly related to
the preceding are the species of Palaotherium, which have
a historical interest as being amongst the first of the Tertiary
Mammals investigated by the illustrious Cuvier. Several
species of Palaothere are known, varying greatly in size, the
smallest being little bigger than a hare, whilst the largest must
have equalled a good-sized horse in its dimensions. The
species of Palaotherium appear to have agreed with the

THE EOCENE PERIOD. 311

existing Tapirs in possessing a lengthened and flexible nose,
which formed a short proboscis or trunk (fig. 229), suitable as
an instrument for stripping off the foliage of trees — the char-

Fig. 229. — Outline of PalcROthenum magnum, restored. Upper Eocene, Europe.
(After Cuvier.)

acters of the molar teeth showing them to have been strictly
herbivorous in their habits. They differ, however, from the
Tapirs, amongst other characters, in the fact that both the
fore and the hind feet possessed three toes each ; whereas in
the latter there are four toes on each fore-foot, and the hind-
feet alone are three-toed. The remains of Palaotheria have
been found in such abundance in certain localities as to show
that these animals roamed in great herds over the fertile plains
of France and the south of England during the later portion
of the Eocene period. The accompanying illustration (fig.
229) represents the notion which the great Cuvier was induced
by his researches to form as to the outward appearance of
Palceotherium magnum. Recent discoveries, however, have
rendered it probable that this restoration is in some important
respects inaccurate. Instead of being bulky, massive, and
more or less resembling the living Tapirs in form, it would rather
appear that Palceotherium magnum was in reality a slender,
graceful, and long-necked animal, more closely resembling in
general figure a Llama, or certain of the Antelopes.

The singular genus Anchitherium forms a kind of transition
between the Palaotheria and the true Horses (Equidcc'). The
Horse (fig. 230, D) possesses but one fully-developed toe to

312

HISTORICAL PALEONTOLOGY.

each foot, this being terminated by a single broad hoof, and
representing the middle toe — the third of the typical five-
fingered or five-toed limb of Quadrupeds in general. In
addition, however, to this fully-developed toe, each foot in
the horse carries two rudimentary toes which are concealed
beneath the skin, and are known as the " splint-bones. "
These are respectively the second and fourth toes, in an
aborted condition ; and the first and fifth toes are wholly
wanting. In Plipparion (fig. 230, C), the foot is essentially
like that of the modern Horses, except that the second and
fourth toes no longer are mere " splint-bones, " hidden be-
neath the skin; but have now little hoofs, and hang freely,
but uselessly, by the side of the great middle toe, not being
sufficiently developed to reach the ground. In Anchitherium,
again (fig. 230, B), the foot is three-toed, like that of Hipparion;
but the two lateral toes (the second and fourth) are so far
developed that they now reach the ground. The first digit
(thumb or great toe) is still wanting; as also is the fifth digit

.. 4

Fig. 230.— Skeleton of the foot In various forms belonging to the family of the Equidce,
A, Foot of Orohippus, Eocene ; B, Foot of Anchitherium, Upper Eocene and Lower
Miocene ; C, Foot of Hipparion, Upper Miocene and Pliocene ; D, Foot of| Horse
(Equus), Pliocene and Recent. The figures indicate the numbers of the digits in the
typical five-fingered hand of Mammals . (After Marsh . )

(little finger or little toe). Lastly, the Eocene rocks have
yielded in North America the remains of a small Equine
quadruped, to which Marsh has given the name of Orohippus.
In this singular form — which was not larger than a fox — the
foot (fig. 230, A) carries four toes, all of which are hoofed and
touch the ground, but of which the third toe is still the largest.

THE EOCENE PERIOD. 313

The first toe (thumb or great toe) is still wanting; but in this
ancient representative of the Horses, the fifth or "little " toe
appears for the first time. As all the above-mentioned forms
succeed one another in point of time, it may be regarded as
probable that we shall yet be able to point, with some cer-
tainty, to some still older example of the Equidcc, in which

Fig. 231.— A noplotfierium commune. Eocene Tertiary, France. ( After Cuvier.)

the first digit is developed, and the foot assumes its typical
five-fingered condition.*

Passing on to the Even-toed or Artiodactyle Ungulates, no
representative of the Hippopotamus seems yet to have existed,
but there are several forms (Charopotamus, Hyopotamus, &c.)
more or less closely allied to the Pigs {Suida} ; and the
singular group of the Anoplotherida may be regarded as form-
ing a kind of transition between the Swine and the Ruminants.
The Anoplotheria (fig. 231) were slender in form, the largest
not exceeding a donkey in size, with long tails, and having the
feet terminated by two hoofed toes each, sometimes with a
pair of small accessory hoofs as well. The teeth exhibit the
peculiarity that they are arranged in a continuous series, with-
out any gap or interval between the molars and the canines ; and
the back teeth, like those of all the Ungulates, are adapted for
grinding vegetable food, their crowns resembling in form those
of the true Ruminants. The genera Dichobune and Xiphodon,
of the Middle and Upper Eocene, are closely related to
Anoplotherium, but are more slender and deer-like in form.
No example of the great Ruminant group of the Ungulate
Quadrupeds has as yet been detected in deposits of Eocene
age.

314 HISTORICAL PALEONTOLOGY.

Whilst true Ruminants appear to be unknown, the Eocene
strata of North America have yielded to the researches of
Professor Marsh examples of an extraordinary group (Dino-
cerata), which may be considered as in some respects inter-
mediate between the Ungulates and the Proboscideans. In
Dinoceras itself (fig. 232) we have a large animal, equal in
dimensons to the living Elephants, which it further resembles
in the structure of the massive limbs, except that there are
only four toes to each foot. The upper jaw was devoid of
front teeth, but there were two very large canine teeth, in the
form of tusks directed perpendicularly downwards ; and there
was also a series of six small molars on each. Each upper
jaw-bone carried a bony projection, which was probably of the
nature of a " horn-core, " and was originally sheathed in horn.

Fig. 232.— Skull of Dinoceras mirabilis, greatly reduced. Eocene, North America.
(After Marsh.)

Two similar, but smaller, horn-cores are carried on the nasal
bones; and two much larger projections, also probably of the
nature of horn-cores, were carried upon the forehead. We
may thus infer that Dinoceras possessed three pairs of horns,

THE EOCENE PERIOD. 315

all of which resembled the horns of the Sheep and Oxen in
consisting of a central bony " core," surrounded by a horny
sheath. The nose was not prolonged into a proboscis or
•' trunk, " as in the existing Elephants ; and the tail was short
and slender. Many forms of the Dinocerata are known ; but all
these singular and gigantic quadrupeds appear to have been
confined to the North American continent, and to be restricted
to the Eocene period.

The important order of the Elephants (Proboscidea) is also
not known to have come into existence during the Eocene
period. On the other hand, the great order of the Beasts of
Prey (Carnivora) is represented in Eocene strata by several
formations belonging to different types. Thus the Arctocyon pre-

Fig. 233.— Portion of the skeleton of Vespertilio Parisiensis. Eocene Tertiary, France.

sents us with an Eocene Carnivore more or less closely allied
to the existing Racoons; the Palaonyctis appears to be related
to the recent Civet-cats ; the genus Hy&nodon is in some
respects comparable to the living Hysenas ; and the Canis
Parisiensis of the gypsum-bearing beds of Montmartre may
perhaps be allied to the Foxes.

The order of the Bats (Cheiroptera} is represented in Eocene
strata of the Paris basin (Gypseous series of Montmartre) by
the Vespertilio Parisiensis (fig. 233), an insect-eating Bat very

316 HISTORICAL PALEONTOLOGY.

similar to some of the existing European forms. Lastly, the
Eocene deposits have yielded more or less satisfactory evi-
dence of the existence in Europe at this period of examples of
the orders of the Gnawing Mammals (Rodentia), the Insect-
eating Mammals (Insectivora), and the Monkeys (Quadru-
mana). *

CHAPTER XIX.
THE MIOCENE PERIOD.

The Miocene rocks comprise those Tertiary deposits which
contain less than about 35 per cent of existing species of shells
(Molluscd), and more than 5 per cent — or those deposits in
which the proportion of living shells is less than of extinct
species. They are divisible into a Lower Miocene (Oligocene)
and an Upper Miocene series.

In Britain, the Miocene rocks are very poorly developed,
one of their leading developments being at Bovey Tracy in
Devonshire, where there occur sands, clays, and beds of lignite
or imperfect coal. These strata certain numerous plants,
amongst which are Vines, Figs, the Cinnamon-tree, Palms,
and many Conifers, especially those belonging to the genus
Sequoia (the "Red-woods"). These Bovey Tracy lignites are
of Lower Miocene age, and they are lacustrine in origin. Also
of Lower Miocene age are the so-called " Hempstead Beds "
of Yarmouth in the Isle of Wight. These attain a thickness of
less than 200 feet, and are shown by their numerous fossils to
be principally a true marine formation. Lastly, the Duke of
Argyll, in 1851, showed that there existed at Ardtun, in the
island of Mull, certain Tertiary strata containing numerous
remains of plants ; and these also are now regarded as belong-
ing to the Lower Miocene.

* A short list of the more important works relating to the Eocene
rocks and fossils will be given after all the Tertiary deposits have been
treated of.

THE MIOCENE PERIOD. 317

In France, the Lower Miocene is represented in Auvergne,
Cantal, and Velay, by a great thickness of nearly horizontal
strata of sands, sandstone, clays, marls, and limestones, the
whole of fresh-water origin. The principal fossils of these
lacustrine deposits are Mammalia, of which the remains occur
in great abundance. In the valley of the Loire occur the
typical European deposits of Upper Miocene age. These are
known as the " Faluns, " from a provincial term applied to
shelly sands, employed to spread upon soils which are deficient
in lime; and the Upper Miocene is hence sometimes spoken
of as the " Falunian " formation. The Faluns occur in scat-
tered patches, which are rarely more than 50 feet in thickness,
and consist of sands and marls. The fossils are chiefly marine ;
but there occur also land and fresh-water shells, together with
the remains of numerous Mammals. About 25 per cent of the
shells of the Faluns are identical with existing species. The
sands, limestones, and marls of the Department of Gers, near
the base of the Pyrenees, rendered famous by the number of
Mammalian remains exhumed from them by M. Lartet, also
belong to the age of the Faluns.

In Switzerland, between the Alps and the Jura, there occurs
a great series of Miocene deposits, known collectively as the
" Molasse, " from the soft nature of a greenish sandstone,
which constitutes one of its chief members. It attains a thick-
ness of many thousands of feet, and rises into lofty mountains,
some of which — as the Rigi — are more than 6000 feet in
height. The middle portion of the Molasse is of marine
origin, and is shown by its fossils to be of the age of the
Faluns; but the lower and upper portions of the formation
are mainly or entirely of fresh-water origin. The Lower
Molasse (of Lower Miocene age) has yielded about 500 species
of plants, mostly of tropical or sub-tropical forms. The Upper
Molasse has yielded about the* same number of plants, with
about 900 species of Insects, such as wood-eating Beetles,
Water-beetles, White Ants, Dragon-flies, &c.

In Belgium, strata of both Lower and Upper Miocene age
are known, — the former (Rupelian Clays} containing numerous
marine fossils; whilst the latter (Bolderberg Sands) have
yielded numerous shells corresponding with those of the
Faluns.

In Austria, Miocene strata are largely developed, marine
beds belonging to both the Lower and Upper division of the
formation occurring extensively in the Vienna basin. The

318 HISTORICAL PALAEONTOLOGY.

well-known Brown Coals of Radaboj, in Croatia, with numer-
ous plants and insects, are also of Lower Miocene age.

In Germany, deposits belonging to both the Lower and
Upper division of the Miocene formation are extensively de-
veloped. To the former belong the marine strata of the May-
ence basin, and the marine Rupelian Clay near Berlin ; whilst
a celebrated group of strata belonging to the Upper Miocene
occurs near Epplesheim, in Hesse-Darmstadt, and is well
known for the number of its Mammalian remains.

In Greece, at Pikerme, near Athens, there occurs a celebrated
deposit of Upper Miocene age, well known to palaeontologists
through the researches of M. M. Wagner, Roth, and Gaudry
upon the numerous Mammalia which it contains. In Italy,
also, strata of both Lower and Upper Miocene age are well
developed in the neighborhood of Turin.

In the Siwalik Hills, in India, at the southern foot of the
Himalayas, occurs a series of Upper Miocene strata, which
have become widely celebrated through the researches of Dr.
Falconer and Sir Proby Cautley upon the numerous remains
of Mammals and Reptiles which they contain. Beds of corre-
sponding age, with similar fossils, are known to occur in the
island of Perim in the Gulf of Cambay.

Lastly, Miocene deposits are found in North America, in
New Jersey, Maryland, Virginia, Missouri, California, Oregon,
&c., attaining a thickness of 1500 feet or more. They consist
principally of clays, sands, and sandstones, sometimes of
marine and sometimes of fresh-water origin. Near Richmond,
in Virginia, there occurs a remarkable stratum, wrongly called
" Infusorial Earth, " which is occasionally 30 feet in thickness,
and consists almost wholly of the siliceous envelopes of cer-
tain low forms of plants (Diatoms), along with the spicules of
Sponges and other siliceous organisms (see fig. 16). The
White River Group of Hayden occurs in the Upper Missouri
region, and is largely exposed over the barren and desolate
district known as the " Mauvaises Terres. " They have a
thickness of 1000 feet or more, and contain numerous remains
of Mammals. They are of lacustrine origin, and are believed
to be of the age of the Lower Miocene. Upon the whole,
about from 15 to 30 per cent of the Mollusca of the American
Miocene are identical with existing species.

In addition to the regions previously enumerated, Miocene
strata are known to be developed in Greenland, Iceland, Spits-
bergen, and in other areas of less importance.

THE MIOCENE PERIOD.

319

The life ot the Miocene period is extremely abundant, and,
from the nature of the deposits of this age, also extremely
varied in its character. The marine beds of the formation
have yielded numerous remains of both Vertebrate and Inver-
tebrate sea-animals; whilst the fresh-water deposits contain
the skeletons of such shells, fishes, &c., as now inhabit rivers
or lakes. Both the marine and the lacustrine beds have been
shown to contain an enormous number of plants, the latter
more particularly; whilst the Brown Coals of the format im
are made up of vegetable matter little altered from its original
condition. The remains of air-breathing animals, such as
Insects, Reptiles, Birds, and Mammals, are also abundantly
found, more especially in the fresh-water beds.

The plants of the Miocene period are extraordinarily num-
erous, and only some of the general features of the vegetation of
this epoch can be indicated here. Our chief sources of informa-
tion as to the Miocene plants are the Brown Coals of Germany
and Austria, the Lower and Upper Molasse of Switzerland,
and the Miocene strata of the Arctic regions. The lignites of
Austria have yielded very numerous plants, chiefly of a tropical
character — one of the most noticeable forms being a Palm of

Fig. 234.— Miocene Palms. A, Chamcerops Helvetica ; B, Sabal major.
Lower Miocene of Switzerland and France.

the genus Sabal (fig. 234, B), now found in America. The
plants of the Lower Miocene of Switzerland are also mostly
of a tropical character, but include several forms now found
in North America, such as a Tulip-tree {Liriodendron} and a
Cypress (Taxodium}. Amongst the more remarkable forms
from these beds may be mentioned Fan-Palms (Chauiarops,
fig. 234, A), numerous tropical ferns, and two species of Cin-

320

HISTORICAL PALEONTOLOGY.

namon. The plant-remains of the Upper Molasse of Switzer-
land indicate an extraordinarily rank and luxuriant vegetation,
composed mainly of plants which now live in warm countries.
Among the commoner plants of this formation may be enumer-
ated many species of Maple (Acer), Plane-trees (Platanus

Fig. 235.— Platanus aceroides, an
Upper Miocene Plane-tree. «, Leaf ;
b, The core of a bundle of fruits ; c,
A single fruit.

Fig. 236. — Cinnamo-
mum polymorphum. a,
Leaf ; 6, Flower. Upper
Miocene.

fig. 235), Cinnamon-trees (fig. 236), and other members of the
Lauracece, many species of Proteacea (Banksia, Grevillea, &c.),
several species of Sarsaparilla (Smilax), Palms, Cypresses, &c.

In Britain, the Lower Miocene strata of Bovey Tracy have
yielded remains of Ferns, Vines, Fig, Cinnamon, Proteaceaz,
&c., along with numerous Conifers. The most abundant of
these last is a gigantic pine — the Sequoia Couttsia — which is
very nearly allied to the huge Sequoia (W ellingtonia) gigantea
of California. A nearly-allied form (Sequoia Langsdorffi} has
been detected in the leaf-bed of Ardtun, in the Hebrides.

In Greenland, as well as in other parts of the Arctic regions,
Miocene strata have been discovered which have yielded a
great number of plants, many of which are identical with
species found in the European Miocene. Amongst these
plants are found many trees, such as Conifers, Beeches, Oaks,
Maples, Plane-trees, Walnuts, Magnolias, &c., with numerous
shrubs, ferns, and other smaller plants. With regard to the
Miocene flora of the Arctic regions, Sir Charles Lyell remarks
that "more than thirty species of Coniferse have been found,
including several Sequoias (allied to the gigantic Wellingtonia
of California), with species of Thujopsis and Salisburia, now

THE MIOCENE PERIOD. 321

peculiar to Japan. There are also beeches, oaks, planes,
poplars, maples, walnuts, limes, and even a magnolia, two
cones of which have recently been obtained, proving that
this splendid evergreen not only lived but ripened its fruit
within the Arctic circle. Many of the limes, planes, and
oaks were large-leaved species ; and both flowers and fruits,
besides immense quantities of leaves, are in many cases pre-
served. Among the shrubs are many evergreens, as Andro-
meda, and two extinct genera, Daphnogene and M'Clintockia,
with fine leathery leaves, together with hazel, blackthorn,
holly, logwood, and hawthorn. A species of Zamia (Zamites)
grew in the swamps, with Potanwgeton, Sparganium, and
Menyanthes; while ivy and vines twined around the forest-
trees, and the broad-level ferns grew beneath their shade. Even
in Spitzbergen, as far north as lat. 78° 56', no less than ninety-
five species of fossil plants have been obtained, including
Taxodium of two species, hazel, poplar, alder, beech, plane-
tree, and lime. Such a vigorous growth of trees within 12° of
the pole, where now a dwarf willow and a few herbaceous
plants form the only vegetation, and where the ground is
covered with almost perpetual snow and ice, is truly remark-
able. "

Taking the Miocene flora as a whole, Dr. Heer concludes
from his study of about 3000 plants contained in the Euro-
pean Miocene alone, that the Miocene plants indicate tropical
or sub-tropical conditions, but that there is a striking inter-
mixture of forms which are at present found in countries
widely removed from one another. It is impossible to state
with certainty how many of the Miocene plants belong to
existing species, but it appears that the larger number are
extinct. According to Heer, the American types of plants
are most largely represented in the Miocene flora, next those
of Europe and Asia, next those of Africa, and lastly those of
Australia. Upon the whole, however, the Miocene flora of
Europe is mostly nearly allied to the plants which we now
find inhabiting the warmer parts of the United States ; and
this has led to the suggestion that in Miocene times the
Atlantic Ocean was dry land, and that a migration of Ameri-
can plants to Europe was thus permitted. This view is borne
out by the fact that the .Miocene plants of Europe are most
nearly allied to the living plants of the eastern or Atlantic
seaboard of the United States, and also by the occurrence of
a rich Miocene flora in Greenland. As regards Greenland,
21

322 HISTORICAL PALEONTOLOGY.

Dr. Heer has determined that the Miocene plants indicate a
temperate climate in that country, with a mean annual tem-
perature at least 30° warmer than it is at present.

The present limit of trees is the isothermal which gives the
mean temperature of 50° Fahr. in July, or about the parallel
of 67° N. latitude. In Miocene times, however, the Limes,
Cypresses, and Plane-trees reach the 79th degree of latitude,
and the Pines and Poplars must have ranged even further
north than this.

The Invertebrate Animals of the Miocene period are very
numerous, but they belong for the most part to existing types,
and they can only receive scanty consideration here. The
little shells of Foratninifera are extremely abundant in some
beds, the genera being in many cases such as now flourish
abundantly in our seas. The principal forms belong to the
genera Textularia (fig. 237), Robulina, Glandulina, Poly-
stomella, Amplristegina, &c.
Corals are very abundant,
in many instances forming
regular " reefs ; " but all the
more important groups are
in existence at the present
day. The Red Coral (Cor-
allium'), so largely sought
after as an ornamental ma-
terial, appears for the first

Fig. 237 .—Textularia Meyeriana, greatly
time in deposits of this age. enlarged. Miocene Tertiary.

Amongst the • Echinoderms,

we meet with Heart-Urchins (Spataugus), Cake-Urchins
(Scutella, fig. 238), and various other forms, the majority of
which are closely allied to forms now in existence.

Numerous Crabs and Lobsters represent the Crustacea; but
the most important of the Miocene Articulate Animals are the
Insects. Of these, more than thirteen hundred species have
been determined by Dr. Heer from the Miocene strata of
Switzerland alone. They include almost all the existing
orders of insects, such as numerous and varied forms of
Beetles (Coleoptera), Forest-bugs (Hemiptera}, Ants (Hymen-
optera), Flies (Diptera), Termites and Dragon-flies (Neurop-
tera), Grasshoppers (Orthoptera), and Butterflies (Lepidoptera}.
One of the latter, the well-known Vanessa Pluto of the Brown
Coals of Croatia, even exhibits the pattern of the wing, and to
some extent its original coloration; whilst the more durably-

THE MIOCENE PERIOD. 323

constructed insects are often in a state of exquisite preser-
vation.

The Mollusca of the Miocene period are very numerous,
but call for little special comment. Upon the whole, they are
generically very similar to the Shell-fish of the present day;
whilst, as before stated, from fifteen to thirty per cent of the

Fig. 238.— Different views of Scutella svbrotnnda, a Miocene " Cake- Urchin '
from the south of France.

species are identical with those now in existence. So far as the
European area is concerned, the Molluscs indicate a decidedly
hotter climate than the present one, though they have not such
a distinctly tropical character as is the case with the Eocene
shells. Thus we meet with many Cones, Volutes, Cowries,
Olive-shells, Fig-shells, and the like, which are decidedly
indicative of a high temperature of the sea. Polysoans are
abundant, and often attain considerable dimensions ; whilst
Brachlopods, on the other hand, are few in number. Bivalves
and Univalves are extremely plentiful ; and we meet here with
the shells of Winged-Snails (Pteropods}, belonging to such
existing genera as Hyalea (fig. 239) and Cleodora. Lastly,
the Cephalofods are represent-
ed both by the chambered
shells of Nautili and by the
internal skeletons of Cuttle-
fishes (Spirulirostra.}

The Fishes of the Miocene Fig. 239— Different views of the shell
period are very abundant, but $£valM Orb^an^ a Miocene ««o-
of little special importance.

Besides the remains of Bony Fishes, we meet in the marine
deposits of this age with numerous pointed teeth belonging
to different kinds of Sharks. Some of the genera of these —
such as Car char odon (fig. 241), Oxyrhina (fig. 240), Lamna,
and Galeocerdo — are very widely distributed, ranging through
both the Old and New Worlds; and some of the species attain
gigantic dimensions.

324 HISTORICAL PALEONTOLOGY.

Amongst the Amphibians we meet with distinctly modern
types, such as Frogs (Rana)
and Newts or Salamanders.
The most celebrated of the
latter is the famous Andrias
Sclieuchzeri (fig. 242), dis-
covered in the year 1725
in the fresh-water Miocene
deposits of CEningen, in
Switzerland. The skeleton
indicates an animal nearly
five feet in length; and it Fig. 240. - Tooth rig, 241. - Tooth

. . of Oxyrhina xiph- of Carcharodon pro-

was originally described by odon. Miocene. ductus. Miocene.

Scheuchzer, a Swiss physi-
cian, in a dissertation published in 1731, as the remains of one
of the human beings who were in existence at the time of the
Noachian Deluge. Hence he applied to it the name of Homo
diluv'n test is. In reality, however, as shown by Cuvier, we
have here the skeleton of a huge Newt, very closely allied to
the Giant Salamander (Menopoma maxima} of Java.

The remains of Reptiles are far from uncommon in the
Miocene rocks, consisting principally of Chelonians and Cro-
codilians. The Land-tortoises (Tcstudinidce} make their first
appearance during this period. The most remarkable form
of this group is the huge Colossochelys Atlas of the Upper
Miocene deposits of the Siwalik Hills in India, described by
Dr. Falconer and Sir Proby Cautley. Far exceeding any
living Tortoise in its dimensions, this enormous animal is
estimated as having had a length of about twenty feet, measured
from the tip of the snout to the extremity of the tail, and
to have stood upwards of seven feet high. All the details of its
organization, however, prove that it must have been " strictly
a land animal, with herbivorous habits, and probably of the
most inoffensive nature. " The accomplished palaeontologist
just quoted, shows further that some of the traditions of the
Hindoos would render it not improbable that this colossal
Tortoise had survived into the earlier portion of the human
period.

Of the Birds of the Miocene period it is sufficient to re-
mark that though specifically distinct, they belong, so far as
known, wholly to existing groups, and therefore present no
points of special palasontological interest.

The Mammals of the Miocene are very numerous, and only

THE MIOCENE PERIOD. 325

242 —Front portion of the skeleton of Andrias Scheuclizeri, a Giant Salamander
from the Miocene Tertiary of (Eningen, In Switzerland. Reduced in size.

326 HISTORICAL PALEONTOLOGY.

the more important forms can be here alluded to. Amongst
the Marsupials, the Old World still continued to possess
species of Opossum (Didephys), allied to the existing American
forms. The Edentates (Sloths, Armadillos, and Ant-eaters), at
the present day mainly South American, are represented by
two large European forms. One of these is the large Macro-
thcrium giganteum of the Upper Miocene of Gers in Southern
France, which appears to have been in many respects allied to
the existing Scaly Ant-eaters or Pangolins, at the same time
that the disproportionately long fore-limbs would indicate that
it possessed the climbing habits of the Sloths. The other is
the still more gigantic Ancylotherium Pentelici of the Upper
Miocene of Pikerme, which seems to have been as large as, or
larger than, the Rhinoceros, and which must have been terres-
trial in its habits. This conclusion is further borne out by the
comparative equality of length which subsists between the fore
and hind limbs, and is not affected by the curvature and
crookedness of the claws, this latter feature being well marked
in such existing terrestrial Edentates as the Great Ant-eater.

, The aquatic Sirenians and Cetaceans are represented in
Miocene times by various forms of no special importance.
Amongst the former, the previously existing genus Halitherium
continued to survive, and amongst the latter we meet with
remains of Dolphins and of Whales of the " Zeuglodont "
family. We may also note here the first appearance of true
" Whalebone Whales," two species of which, resembling the
living " Right Whale " of Arctic seas, and belonging to the
same genus (Balana), have been detected in the Miocene
beds of North America.

The great order of the Ungulates or Hoofed Quadrupeds is
very largely developed in strata of Miocene age, various new
types of this group making their appearance here for the first
time, whilst some of the characteristic genera of the preceding
period are still represented under new shapes. Amongst the
Odd-toed or " Perissodactyle " Ungulates, we meet for the first
time with representatives of the family Rhino cerida compris-
ing only the existing Rhinoceroses. In India in the Upper
Miocene beds of the Sikalik Hills, and in North America,
several species of Rhinoceros have been detected, agreeing with
the existing forms in possessing three toes to each foot, and in
having one or two solid fibrous "horns" carried upon the front
of the head. On the other hand, the forms of this group which
distinguish the Miocene deposits of Europe appear to have

THE MIOCENE PERIOD. 327

been for the most part hornless, and to have resembled the
Tapirs in having three-toed hind-feet, but four-toed fore-feet.

The family of the Tapirs is represented, both in the Old
and New Worlds, by species of the genus Lophiodon, some of
which were quite diminutive in point of size, whilst others
attained the dimensions of a horse. Nearly allied to this
family, also, is the singular group of quadrupeds which Marsh
has described from the Miocene strata of the United States
under the name of Brontotheridcr. These extraordinary ani-
mals, typified by Brontnthcrium (fig. 243) itself, agree with the

Fig. 243.— Skull of Brontotherium ingem. Miocene Tertiary, United States.
(After Marsh.)

existing Tapirs of South America and the Indian Archipelago
in having the fore-feet four-toed, whilst the hind-feet are three-
toed ; and a further point of resemblance is found in the fact
(as shown by the form of the nasal bones) that the nose was
long and flexible, forming a short movable proboscis or trunk,
by means of which the animal was enabled to browse on
shrubs or trees. They differ, however, from the Tapirs, not
only in the apparent presence of a long tail, but also in the
possession of a pair of very large " horn-cores, " carried upon
the nasal bones, indicating that the animal possessed horns of
a similar structure to those of the " Hollow-horned " Rumin-
ants (e. g., Sheep and Oxen). Brontotherium gigas is said to be
nearly as large as an Elephant, whilst B. ingens appears to
have attained dimensions still more gigantic. The well-known
genus Titan otheriunt of the American Miocene would also
appear to belong to this group.

The family of the Horses (Equidcr} appears under various
forms in the Miocene, but the most important and best known

328 HISTORICAL PALAEONTOLOGY.

of these is Hipparion. In this genus the general conformation
of the skeleton is extremely similar to that of the existing
Horses, and the external appearance of the animal must have
been very much the same. The foot of Hipparion, however,
as has been previously mentioned, differed from that of the
Horse in the fact that whilst both possess the middle toe greatly
developed and enclosed in a broad hoof, the former, in addition,
possessed two lateral toes, which were sufficiently developed
to carry hoofs, but were so far rudimentary that they hung idly
by the side of the central toe without touching the ground
(see fig. 230). In the Horse, on the other hand, these lateral
toes, though present, are not only functionally useless, but are
concealed beneath the skin. Remains of the Hipparion have
been found in various regions in Europe and in India; and
from the immense quantities of their bones found in certain
localities, it may be safely inferred that these Middle Tertiary
ancestors of the Horses lived, like their modern representa-
tives, in great herds, and in open grassy plains or prairies.

Amongst the Even-toed or Artiodactyle Ungulates, we for
the first time meet with examples of the Hippopotamus, with its
four-toed feet, its massive body, and huge tusk-like lower
canine teeth. The Miocene deposits of Europe have not
hitherto yielded any remains of Hippopotamus; but several
species have been detected in the Upper Miocene of the Siwalik
Hills by Dr. Falconer and Sir Proby Cautley. These ancient
Indian forms, however, differ from the existing Hippopotamus
amphibius of Africa in the fact that they possessed six incisor
teeth in each jaw (fig. 244), whereas the latter has only four.

Amongst the other Even-toed Ungulates, the family of the
Pigs (Suida) is represented by true Swine (Sus EryuwntJiius),
Peccaries (Dicotyles antiquus}, and by forms which, like the
great Elotherium of the American Miocene, have no represen-
tative at the present day. The Upper Miocene of India has
yielded examples of the Camels. Small Musk-deer (AmpJii-
tragulus and Dremotheriuin} are known to have existed in
France and Greece; and the true Deer (Cervidcc}, with their
solid bony antlers, appear for the first time here in the person of
species allied to the living Stags (Cervus), accompanied by the
extinct genus Dorcatherium. The Giraffes (Camelopardalidce'),
now confined to Africa, are known to have lived in India and
Greece; and the allied Helladotherium, in some respects inter-
mediate between the Giraffes and the Antelopes, ranged over
Southern Europe from Attica to France. The great group of

THE MIOCENE PERIOD.

329

the "Hollow-horned" Ruminants (Cavicornia}, lastly, came
into existence in the Miocene period; and though the typical
families of the Sheep and Oxen are apparently wanting, there
are true Antelopes, together with forms which, if systematic-

rig. 244.- a, Skull of Hippopotamus Sivalerwis, viewed from below, one-eighth of
the natural size ; b, Molar tooth of the same, showing the surface of the crown, one-
half of the natural size ; c, Front of the lower jaw of the same, showing the six incisors
and the tusk-like canines, one-eighth of the natural size. Upper Miocene, Siwulik
Hills. (After Falconer'and Cautley.)

ally referable to the Antilopida, nevertheless are more or less
clearly transitional between this and the family of the Sheep
and Goats. Thus the Palaoreas of the Upper Miocene of
Greece may be regarded as a genuine Antelope; but the
Tragoceras of the same deposit is intermediate in its characters
between the typical Antelopes and the Goats. Perhaps the
most remarkable, however, of these Miocene Ruminants is the
Sivatherium giganteum (fig. 245) of the Siwalik Hills, in India.
In this extraordinary animal there were two pairs of horns,
supported by bony " horn-cores, " so that there can be no
hesitation in referring Sivatherium to the Cavicorn Rumin-
ants. If all these horns had been simple, there would have

330 HISTORICAL PALAEONTOLOGY.

been no difficulty in considering Sivatherium as simply a
gigantic four-horned Antelope, essentially similar to the living
Antilope (Tetraceros) quadriconiis of India. The hinder pair
of horns, however, is not only much larger than the front pair,
but each possesses two branches or snags — a peculiarity not to
be paralleled amongst any existing Antelope, save the abnormal
Prongbuck (Antilocapra) of North America. Dr. Murie, how-
ever, in an admirable memoir on the structure and relationships
of Sivatherium, has drawn attention to the fact that the Prong-

Fig. 245.— Skull of Sivat/teriain giganteum, reduced In size. Miocene, India.
(After Murie.)

buck sheds the sheath of its horns annually, and has suggested
that this may also have been the case with the extinct form.
This conjecture is rendered probable, amongst other reasons,
by the fact that no traces of a horny sheath surrounding the
horn-cores of the Indian fossil have been as yet detected.
Upon the whole, therefore, we may regard the elephantine
Sivatherium as being most nearly allied to the Prongbuck of
Western America, and thus as belonging to the family of the
Antelopes,

THE MIOCENE PERIOD.

It is to the Miocene period, again, to which we must refer
the first appearance of the important order of the Elephants
and their allies (Proboscideans), all of which are characterized
by their elongated trunk-like noses, the possession of five toes to
the foot, the absence of canine teeth, the development of two
or more of the incisor teeth into long tusks, and the adaptation
of the molar teeth to a vegetable diet. Only three generic
groups of this order are known — namely, the extinct Deino-
therium, the equally extinct Mastodons, and the Elephants; and
all these three types are known to have been in existence as
early as the Miocene period, the first of them being exclusively
confined to deposits of this age. Of the three, the genus
Deincthcrium is much the most abnormal in its characters;
so much so, that good authorities regard it as being one
of the Sea-cows (Sirenia) — though this view has been rendered
untenable by the discovery of limb-bones which can hardly
belong to any other animal, and which are distinctly Probosci-
dean in type. The most celebrated skull of the Deinothere
(fig. 246) is one which was exhumed from the Upper Miocene
deposits of Epplesheim, in Hesse-
Darmstadt, in the year 1836.
This skull was four and a half
feet in length, and indicated an
animal larger than any existing
species of Elephant. The upper
jaw is destitute of incisor or
canine teeth, but is furnished on
each side with five molars, which
are opposed to a corresponding
series of grinding teeth in the
lower jaw. No canines are pres-
ent in the lower jaw; but the
front portion of the jaw is ab-
ruptly bent downwards, and car-
ries two huge tusk-like incisor
teeth, which are curved down-
wards and backwards, and the use of which is rather problem-
atical. Not only does the Deinothere occur in Europe, but
remains belonging to this genus have also been detected in the
Siwalik Hills, in India.

The true Elephants (Elcphas} do not appear to have ex-
isted during the Miocene period in Europe, but several species
have been detected in the Upper Miocene deposits of the

Fig. 246 —Skull of Deinotherium
gigdnteum, greatly reduced. From
the Upper Miocene of Germany.

332

HISTORICAL PALAEONTOLOGY.

Siwalik Hills, in India. The fossil forms, though in all cases
specifically, and in some cases even sub-generically, distinct,
agree with those now in existence in the general conformation
of their skeleton, and in the principal characters of their den-
tition. In all, the canine teeth are wanting in both jaws; and
there are no incisor teeth in the lower jaw, whilst there are
two incisors in the front of the upper jaw, which are de-
veloped into two huge " tusks. " There are six molar teeth
on each side of both the upper and lower jaw, but only

B

Fig. 247. — A, Molar tooth of Elephas planifrons, one-third of the natural size, show-
ing the grinding surface — from the Upper Miocene of India ; B. Profile view of the
last upper inolar of .Mastodon Sivalensis, one-third of the natural size — from the Upper
Miocene of India. (After Falconer.)

one, or at most a part of two, is in actual use at any given
time; and as this becomes worn away, it is pushed forward
and replaced by its successor behind it. The molars are of
very large size, and are each composed of a number of trans-

THE MIOCENE PERIOD. 333

verse plates of enamel united together by ivory ; and by the
process of mastication, the teeth become worn down to a flat
surface, crossed by the enamel-ridges in varying patterns.
These patterns are different in the different species of Ele-
phants, though constant for each; and they constitute one of
the most readily available means of separating the fossil
forms from one another. Of the seven Miocene Elephants
of India, as judged by the characters of the molar teeth,
two are allied to the existing Indian Elephant, one is related
to the living African Elephant, and the remaining four are in
some respects intermediate between the true Elephants and
the Mastodons.

The Mastodons, lastly, though quite elephantine in their
general characters, possess molar teeth which have their crowns
furnished with conical eminences or tubercles placed in pairs
(fig. 247, B), instead of having the approximately flat surface
characteristic of the grinders of the Elephants. As in the
latter, there are two upper incisor teeth, which grow perma-
nently during the life of the animal, and which constitute great
tusks; but the Mastodons, in addition, o'ften possess two lower
incisors, which in some cases likewise grow into small tusks.
Three species of Mastodon are known to occur in the Upper
Miocene of the Siwalik Hills of India; and the Miocene de-
posits of the European area have yielded the remains of four
species, of which the best known are the M. longirostris and the
M. angustidens.

Whilst herbivorous Quadrupeds, as we have seen, were
extremely abundant during Miocene times, and often attained
gigantic dimensions, Beasts of Prey (Carnivora) were by no
means wanting, most of the principal existing families of the
order being represented in deposits of this age. Thus, we find
aquatic Carnivores belonging to both the living groups of the
Seals and Walruses; true Bears are wanting, but their place
is filled by the closely-allied genus Amphicyon, of which various
species are known; Weasels and Otters were not unknown,
and the Hycunictis and Ictitherium of the Upper Miocene of
Greece are apparently intermediate between the Civet-cats and
the Hyaenas; whilst the great Cats of subsequent periods are
more than adequately represented by the huge " Sabre-toothed
Tiger" (Machairodus), with its immense trenchant and serrated
canine teeth.

Amongst the Rodent Mammals, the Miocene rocks have
yielded remains of Rabbits, Porcupines (such as the Hystrix

334 HISTORICAL PALAEONTOLOGY.

primigenius of Greece), Beavers, Mice, Jerboas, Squirrels, and
Marmots. All the principal living groups of this order were
therefore differentiated in Middle Tertiary times.

The Cheiroptera are represented by small insect-eating Bats ;
and the order of the Insectivorous Mammals is represented by
Moles, Shrew-mice, and Hedgehogs.

Lastly, the Monkeys (Quadrumana) appear to have existed
during the Miocene period under a variety of forms, remains
of these animals having been found both in Europe and in
India; but no member of this order has as yet been detected
in the Miocene Tertiary of the North American continent.
Amongst the Old World Monkeys of the Miocene, the two
most interesting are the PliopitJiecus and Dryopithecus of France.

Fig. 248.— Lower jaw of Pliapitliecus antiquus. Upper Miocene, France.

The former of these (fig. 248) is supposed to have been most
nearly related to the living Semno pithed of Southern Asia, in
which case it must have possessed a long tail. The Mesopi-
thecus of the Upper Miocene of Greece is also one of the lower
Monkeys, as it is most closely allied to the existing Macaques.
On the other hand, the Dryopithecus of the French Upper
Miocene is referable to the group of the " Anthropoid Apes, "
and is most nearly related to the Gibbons of the present day,
in which the tail is rudimentary and there are no cheek-
pouches. Dryopithecus was, also, of large size, equalling Man
in stature, and apparently living amongst the trees and feed-
ing upon fruits.

THE PLIOCENE PERIOD. 335

CHAPTER XX.
THE PLIOCENE PERIOD.

The highest division of the Tertiary deposits is termed the
Pliocene formation, in accordance with the classification pro-
posed by Sir Charles Lyell. The Pliocene formations contain
from 45 to 95 per cent of existing species of Mollusca, the re-
mainder belonging to extinct species. They are divided by Sir
Charles Lyell into two divisions, the Older Pliocene and Newer
Pliocene.

The Pliocene deposits of Britain occur in Suffolk, and are
known by the name of " Crags," this being a local term used
for certain shelly sands, which are employed in agriculture.
Two of these Crags are referable to the Older Pliocene, viz.,
the White and Red Crags, — and one belongs to the Newer
Pliocene, viz., the Norwich Crag.

The White or Coralline Crag of Suffolk is the oldest of the
Pliocene deposits of Britain, and is an exceedingly local for-
mation occurring in but a single small area, and having a
maximum thickness of not more than 50 feet. It consists of
soft sands, with occasional intercalations of flaggy limestone.
Though of small extent and thickness, the Coralline Crag is of
importance from the number of fossils which it contains. The
name " Coralline " is a misnomer ; since there are few true
Corals, and the so-called " Corals " of the formation are really
Polyzoa, often of very singular forms. The shells of the Coral-
line Crag are mostly such as inhabit the seas of temperate
regions; but there occur some forms usually looked upon as
indicating a warm climate.

The Upper or Red Crag of Suffolk — like the Coralline Crag
— has a limited geographical extent and a small thickness,
rarely exceeding 40 feet. It consists of quartzose sands, usu-
ally deep red or brown in color, and charged with numerous
fossils.

Altogether more than 200 species of shells are known from
the Red Crag, of which 60 per cent are referable to existing

336 HISTORICAL PALEONTOLOGY.

species. The shells indicate, upon the whole, a temperate or
even cold climate, decidedly less warm than that indicated by
the organic remains of the Coralline Crag. It appears, there-
fore, that a gradual refrigeration was going on during the
Pliocene period, commencing in the Coralline Crag, becoming
intensified in the Red Crag, being still more severe in the
Norwich Crag, and finally culminating in the Arctic cold of the
Glacial period.

Besides the Mollusca, the Red Crag contains the ear-bones
of Whales, the teeth of Sharks and Rays, and remains of the
Mastodon, Rhinoceros, and Tapir.

The Newer Pliocene deposits are represented in Britain by
the Norwich Crag, a local formation occurring near Norwich.
It consists of incoherent sands, loams, and gravels, resting in
detached patches, from 2 to 20 feet in thickness, upon an
eroded surface of Chalk. The Norwich Crag contains a mix-
ture of marine, land, and fresh-water shells, with remains of
fishes and bones of mammals; so that it must have been de-
posited at a local sea-deposit near the mouth of an ancient
river. It contains altogether more than 100 marine shells,
of which 89 per cent belong to existing species. Of the
Mammals, the two most important are an Elephant (Elefihas
meridionalis), and the characteristic Pliocene Mastodon (M.
Arvernensis} , which is hitherto the only Mastodon found in
Britain.

According to the most recent views of high authorities,
certain deposits — such as the so-called " Bridlington Crag " of
Yorkshire, and the " Chillesford beds " of Suffolk — are to be
also included in the Newer Pliocene, upon the ground that
they contain a small proportion of extinct shells. Our knowl-
edge, however, of the existing Molluscan fauna,, is still so far
incomplete, that it may reasonably be doubted if these sup-
posed extinct forms have actually made their final disappear-
ance, whilst the strata in question have a strong natural con-
nection with the " Glacial deposits," as shown by the number
of Arctic Mollusca which they contain. Here, therefore, these
beds will be included in the Post-Pliocene series, in spite of
the fact that some of their species of shells are not known to
exist at the present day.

The following are the more important Pliocene deposits
which have been hitherto recognized out of Britain : —

I. In the neighborhood of Antwerp occur certain "crags,"

THE PLIOCENE PERIOD. 3S7

which are the equivalent of the White and Red Crag in part.
The lowest of these contains less than 50 per cent, and the
highest 60 per cent, of existing species of shells, the remainder
being extinct.

2. Bordering the chain of the Apennines, in Italy, on both
sides is a series of low hills made up of Tertiary strata, which
are known as the Sub-Apennine beds. Part of these is of
Miocene age, part is Older Pliocene, and a portion is Newer
Pliocene. The Older Pliocene portion of the Sub-Apennines
consists of blue or brown marls, which sometimes attain a
thickness of 2000 feet.

3. In the valley of the Arno, above Florence, are both
Older and Newer Pliocene strata. The former consist of blue
clays and lignites, with an abundance of plants. The latter
consist of sands and conglomerates, with remains of large Car-
nivorous Mammals, Mastodon, Elephant, Rhinoceros, Hippo-
potamus, &c.'

4. In Sicily, Newer Pliocene strata are probably more largely
developed than anywhere else in the world, rising sometimes
to a height of 3000 feet above the sea. The series consists
of clays, marls, sands, and conglomerates, capped by a com-
pact limestone, which attains a thickness of from 700 to 800
feet. The fossils of these beds belong almost entirely to living
species, one of the commonest being the Great Scallop of the
Mediterranean (Pecten Jacobaus).

5. Occupying an extensive area round the Caspian, Aral,
and Azof Seas, are Pliocene deposits known as the " Aralo-
Caspian " beds. The fossils in these beds are partly fresh-
water, partly marine, and partly intermediate in character, and
they are in great part identical with -species now inhabiting
the Caspian. The entire formation appears to indicate the
former existence of a great sheet of brackish water, forming an
inland sea, like the Caspian, but as large as, or larger than, the
Mediterranean.

6. In the United States, strata of Pliocene age are found in
North and South Carolina. They consist of sands and clays,
with numerous fossils, chiefly Molluscs and Echinoderms.
From 40 to 60 per cent of the fossils belong to existing
species. On the Loup Fork of the river Platte, in the Upper
Missouri region, are strata which are also believed to be refer-
able to the Pliocene period, and probably to its upper division.
They are from 300 to 400 feet thick, and contain land-shells,

22

338 HISTORICAL PALEONTOLOGY.

with the bones of numerous Mammals, such as Camels, Rhino-
ceroses, Mastodons, Elephants, the Horse, Stag, &c.

As regards the life of the Pliocene period, there are only
two classes of organisms to which our attention need he
directed — namely, the Shell-fish and the Mammals. So far as
the former are concerned, we have to note in the first place
that the introduction of new species of animals upon the globe
went on rapidly during this period. In the Older Pliocene
deposits, the number of shells of existing species is only from
40 to 60 per cent; but in the Newer Pliocene the pro-
portion of living forms rises to as much as from 80 to
95 per cent. Whilst the Molluscs thus become rapidly mod-
ernized, the Mammals still all belong to extinct species,
though modern generic types gradually supersede the more
antiquated forms of the Miocene. In the second place, there
is good evidence to show that the Pliocene period was one in
which the climate of the northern hemisphere underwent a
gradual refrigeration. In the Miocene period, there is evi-
dence to show that Europe possessed a climate very similar
to that now enjoyed by the Southern United States, and cer-
tainly very much warmer than it is at present. The presence
of Palm-trees upon the land, and of numerous large Cowries,
Cones, and other shells of warmer regions in the sea, sufficiently
proves this. In the Older Pliocene deposits, on the other
hand, northern forms predominate amongst the Shells, though
some of the types of hotter regions still survive. In the Newer
Pliocene, again, the Molluscs are such as almost exclusively
inhabit the seas of temperate or even cold regions ; whilst if
we regard deposits like the " Bridlington Crag " and " Chilles-
ford beds " as truly referable to this period, we meet at the
close of this period with shells such as nowadays are distinct-
ively characteristic of high latitudes. It might be thought
that the occurrence of Quadrupeds such as the Elephant,
Rhinoceros, and Hippopotamus, would militate against this
generalization, and would rather support the view that the
climate of Europe and the United States must have been a
hot one during the later portion of the Pliocene period. We
have, however, reason to believe that many of these extinct
Mammals were more abundantly furnished with hair, and more
adapted to withstand a cool temperature, than any of their
living congeners. We have also to recollect that many of
these large herbivorous quadrupeds may have been, and
indeed probably were, more or less migratory in their habits;

THE PLIOCENE PERIOD.

339

and that whilst the winters of the later portion of the Pliocene
period were cold, the summers might have been very hot.
This would allow of a northward migration of such terrestrial
animals during the summer-time, when there would be "an
ample supply of food and a suitably high temperature, and a
southward recession towards the approach of winter.

The chief palaeontological interests of the Pliocene deposits,
as of the succeeding Post- Pliocene, center round the Mammals
of the period ; and amongst the many forms of these we may
restrict our attention to the orders of the Hoofed Quadrupeds
(Ungulates), the Proboscideans, the Carnivora, and the Quad-
rumana. Almost all the other Mammalian orders are more

Fig. 249 — A, Under surface of the skull of Rhinoceros Etruscus, one-seventh of
the natural size — Pliocene, Italy ; B. Crowns of the three true molars of the upper
jaw, left side, of Rhinoceros meaarJiinHs (R. leptorhinun, Falconer), one-half of the
natural size— Pliocene, France. (After Falconer.)

or less fully represented in Pliocene times, but none of them
attains any special interest till we enter upon the Post-Pliocene.

340 HISTORICAL PALEONTOLOGY.

Amongst the Odd-toed Ungulates, in addition to the remains
of true Tapirs (Tapirus Arvernensis} , we meet with the bones
of several species of Rhinoceros, of which the Rhinoceros Etrus-
cus and R. megarhinus (fig. 249) are the most important. The
former of these (fig. 249, A) derives its specific name from its
abundance1 in the Pliocene deposits of the Val d'Arno, near
Florence, and though principally Pliocene in its distribution,
it survived into the earlier portion of the Post-Pliocene period.
Rhinoceros Etruscus agreed with the existing African forms in
having two horns placed one behind the other, the front one
being the longest ; but it was comparatively slight and slender
in its build, whilst the nostrils were separated by an incom-
plete bony partition. In the Rhinoceros megarhinus (fig. 249,
B), on the other hand, no such partition exists between the
nostrils, and the nasal bones are greatly developed in size. It
was a two-horned form, and is found associated with Elephas
meridionalis and E. antiquus in the Pliocene deposits of the
Val d'Arno, near, Florence. Like the preceding, it survived,
in diminished numbers, into the earlier portion of the Post-
Pliocene period.

The Horses (Equidcz) are represented, both in Europe and
America, by the three-toed Hipparions, which survive from the
Miocene, but are now verging upon extinction. For the first
time, also, we meet with genuine Horses (Equus), in which
each foot is provided with a single complete toe only, encased
in a single broad hoof. One of the American species of this
period (the Equus excelsus) quite equalled the modern Horse
in stature ; and it is interesting to note the occurrence of indig-
enous horses in America at such a comparatively late geo-
logical epoch, seeing that this continent certainly possessed
none of these animals when first discovered by the Spaniards.

Amongst the Even-toed Ungulates, we may note the occur-
rence of Swine (Suida), of forms allied to the Camels (Camel-
ides), and of various kinds of Deer (Cervidce) ; but the most
interesting Pliocene Mammals belonging to this section is the
great Hippopotamus major of Britain and Europe. This well-
known species is very closely allied to the living Hippopotamus
amphibius of Africa, from which it is separated only by its
larger dimensions, and by certain points connected with the
conformation of the skeleton. It is found very abundantly in
the Pliocene deposits of Italy and France, associated with the
remains of the Elephant, Mastodon, and Rhinoceros, and it
siirvived into the earlier portion of the Post-Pliocene period.

THE PLIOCENE PERIOD. 341

During this last-mentioned period, it extended its range north-
wards, and is found associated with the Reindeer, the Bison,
and other northern animals. From this fact it has been in-
ferred, with great probability, that the Hippopotamus major was
furnished with a long coat of hair and fur, thus differing from
its nearly hairless modern representative, and resembling its
associates, the Mammoth and the Woolly Rhinoceros.

Passing on to the Pliocene Proboscideans, we find that the
great Deinotheria of the Miocene have now wholly disappeared,
and the sole representatives of the order are Mastodons and
Elephants. The most important member of the former group
is the Mastodon Arvernensis (fig. 250), which ranged widely
over Southern Europe and England, being generally associated
with remains of the Eleplias mcridionalis, E. antiquus, Rhino-
ceros megarhinus, and Hippopotamus major. The lower jaw

Fig. 250. — Third mllk-rnolar of the left side of the upper jaw of Mastodon
Arvernensis, showing the grinding surface. Pliocene.

seems to have been destitute of incisor teeth ; but the upper
incisors are developed into great tusks, which sometimes reach
a length of nine feet, and which have the simple curvature of
the tusks of the existing Elephants. Amongst the Pliocene
Elephants the two most important are the Elephas meridionalis
and the Elephas antiquus. Of these, the Elephas meridionalis
(fig. 251) is found abundantly in the Pliocene deposits of
Southern Europe and England, and also survived into the
•earlier portion of the Post-Pliocene period. Its molar teeth
are of the type of those of the existing African Elephant, the
spaces enclosed by the transverse enamel-plates being more

342 HISTORICAL PALEONTOLOGY.

or less lozenge-shaped, whilst the curvature of the tusks is
simple. The Elephas antiquus (fig. 252) is very generally
associated with the preceding, and it survived to an even
later stage of the Post-Pliocene period. The molar teeth are
of the type of the existing Indian Elephant, with compara-
tively thin enamel-ridges, placed closer together than in the
African type ; whilst the tusks were nearly straight.

Tig. 251.— Molar tooth of Elepha.8 meridionalis, one-third of the natural size.
Pliocene and Post-Pliocene.

Amongst the Pliocene Carnivores, we meet with true Bears
(Ursus Arvernensis), Hyaenas (such as Hyccna Hipparionum),
and genuine Lions (such as the Felis augustus of North
America) ; but the most remarkable of the beasts of prey of
this period is the great "Sabre-toothed Tiger" (Machairodus),

Fig. 252.— Molar tooth of Elephas antiquus, one-third of the natural size.
Pliocene and Post-Pliocene.

species of which existed in the earlier Miocene, and survived
to the later Post-Pliocene. In this remarkable form we are
presented with perhaps the most highly carnivorous type of

THE PLIOCENE PERIOD.

343

all known beasts of prey. Xot only are the jaws shorter in
proportion even than those of the great Cats of the present
clay, but the canine teeth (fig. 253) are of enormous size,
greatly flattened so as to assume the form of a poignard, and

Fig. 25:5.— A. Skull of Mitclinirodua cultridens. without the lower jaw. reduced In
size ; B, Canine tooth of the same, one-half the natural size. Pliocene, France.

having their margins finely serrated. Apart from the charac-
ters of the skull, the remainder of the skeleton, so far as known,
exhibits proofs that the Sabre-toothed Tiger was extraordi-
narily muscular and powerful, and in the highest degree adapt-
ed for a life of rapine. Species of Machairodus must have
been as large as the existing Lion ; and the genus is not only
European, but is represented both in South America and in
India, so that the geographical range of these predaceous
beasts must have been very extensive.

Lastly, we may note that Pliocene deposits of Europe
have yielded the remains of Monkeys (Quadrumana) , allied to
the existing' Semnopitheci and Macaques.

344 HISTORICAL PALEONTOLOGY.

LITERATURE.

The following list comprises a small selection of some of the
more important and readily accessible works and memoirs
relating to the Tertiary rocks and their fossils. With few ex-
ceptions, foreign works relating to the Tertiary strata of the
continent of Europe or their organic remains have been
omitted : —

(1) 'Elements of Geology.' Lyell.

(2) ' Students' Elements of Geology. ' Lyell.

(3) 'Manual of Palaeontology.' Owen.

(4) ' British Fossil Mammals and Birds. ' Owen.

(5) ' Traite de Paleontologie. ' Pictet.

(6) ' Cours Elementaire de Paleontologie. ' D'Orbigny.

(7) "Probable Age of the London Clay," &c. — 'Quart.
Journ. Geol. Soc., ' vol. iii. Prestwich.

(8) ' Structure and Probable Age of the Bagshot Sands ' —

Ibid., vol. iii. Prestwich.

(9) ' Tertiary Formations of the Isle of Wight ' — Ibid.,

vol. ii. Prestwich.
(10) ' Structure of the Strata between the London Clay and

the Chalk, ' &c. — Ibid., vols. vi., viii., and x. Prestwich.
(n) 'Correlation of the Eocene Tertiaries of England,

France, and Belgium' — Ibid,, vol. xxvii. Prestwich.

(12) 'On the Fluvio-marine Formations of the Isle of

Wight' — Ibid., vol. ix. Edward Forbes.

(13) 'Newer Tertiary Deposits of the Sussex Coast' — Ibid.,

vol. xiii. Godwin-Austen.

(14) 'Kainozoic Formations of Belgium' — Ibid., vol. xxii.

Godwin-Austen.

(15) 'Tertiary Strata of Belgium and French Flanders' —

Ibid., vol. viii. Lyell.

(16) 'On Tertiary Leaf-beds in the Isle ©f Mull'— Ibid.,

vol. vii. The Duke of Argyll.

(17) 'Newer Tertiaries of Suffolk and their Fauna' — Ibid.,

vol. xxvi. Ray Lankester.

(18) 'Lower London Tertiaries of Kent' — Ibid., vol. xxii.

AVhitaker.

(19) "Guide to the Geology of London" — 'Mem. Geol.

Survey. ' Whitaker.

(20) 'Memoirs of the Geological Survey of Great Britain.'

(21) 'Introductory Outline of the Geology of the Crag

District' (Supplement to Crag Mollusca, Palseonto-

graphical Society). S. V. Wood, jun., and F. W.
Harmer.

(22) " Tertiary Fluvio-marine Deposits of the Isle of

Wight. " Edward Forbes. Edited by Godwin-
Austen ; with Descriptions of the Fossils by Morris,
Salter, and Rupert Jones — ' Memoirs of the Geo-
logical Survey.'

(23) ' Geological Excursions round the Isle of Wight. '

Mantell.

(24) ' Catalogue of British Fossils. ' Morris,

THE PLIOCENE PERIOD. 345

(25) ' Catalogue of Fossils in the Museum of Practical

Geology.' Etheridge.

(26) 'Monograph of the Crag Polyzoa ' ( Palaeontographical

Society). Busk.

(27) 'Monograph of the Tertiary Brachiopoda ' (Ibid.)

Davidson.

(28) ' Monograph of the Tertiary Malacostracous Crus-

tacea' (Ibid.) Bell.

(29) 'Monograph of the Tertiary Corals' (Ibid.) Milne-
Edwards and Haime.

(30) 'Supplement to the Tertiary Corals' (Ibid.) Martin

Duncan.

(31) 'Monograph of the Eocene Mollusca ' (Ibid.) Fred.

E. Edwards.

(32) 'Monograph of the Eocene Mollusca' (Ibid.) Searles

V. Wood.

(33) 'Monograph of the Crag Mollusca' (Ibid.) Searles

V. Wood.

(34) 'Monograph of the Tertiary Entomostraca ' (Ibid.)

Rupert Jones.

(35) 'Monograph of the Foraminifera of the Crag' (Ibid.)

Rupert Jones, Parker, and H. B. Brady.

(36) ' Monograph of the Radiaria of the London Clay '

(Ibid.) Edward Forbes.

(37) 'Monograph of the Cetace'a of the Red Crag' (Ibid.)

Owen.

(38) ' Monograph of the Fossil Reptiles of the London

Clay' (Ibid.) Owen and Bell.

(39) " On the Skull of a Dentigerous Bird from the Lon-

don Clay of Sheppey " — ' Quart. Journ. Geol. Soc.,'
vol. xxix. Owen.

(40) 'Ossemens Fossiles.' Cuyier.

(41) 'Fauna Antiqua Sivalensis. ' Falconer and Sir Proby

Cautley.

(42) ' Palreontological Memoirs. ' Falconer.

(43) ' Animaux Fossiles et Geologic de 1'Attique. ' Gaudry.

(44) " Principal Characters of the Dinocerata " — ' American

Journ. of Science and Arts, ' vol. xi. Marsh.

(45) 'Principal Characters of the Brontotheridae ' (Ibid.)

Marsh.

(46) 'Principal Characters of the Tillodontia ' (Ibid.)

Marsh.

(47) "Extinct Vertebrata of the Eocene of Wyoming" —

'Geological Survey of Montana,' &c., 1872. Cope.

(48) " Ancient Fauna of Nebraska " — ' Smithsonian Con-

tributions to Knowledge, ' vol. vi. Leidy.

(49) ' Manual of Geology. ' Dana.

(50) " Palaeontology and Evolution " .(Presidential Address

to the Geological Society of London, 1870) — 'Quart.
Journ. Geol. Soc., ' vol. xxvi. Huxley.

(51) 'Mineral Conchology. ' Sowerby.

(52) ' Description des Coquilles Fossiles,' &c. Deshayes.

(53) ' Description des Coquilles Tertiaries de Belgique.'

(54) ' Fossilen Polypen des Wiener Tertiar-beckens.' Reuss,

346 HISTORICAL PALAEONTOLOGY.

(55) ' Palaeontologische Studien tiber die alteren Tertiar-

schichten der Alpen.' Reuss.

(56) ' Land- und Siiss-wasser Conchylien der Vorwelt.'

Sandberger.

(57) ' Flora Tertiaria Helvetica. ' Heer.

(58) ' Flora Fossilis Arctica.' Heer.

(59) ' Recherches sur le Climat et la Vegetation du Pays

Tertiaire.' Heer.

(60) I Fossil Flora of Great Britain.' Lindley and Hutton.

(61) 'Fossil Fruits and Seeds of the London Clay.' Bower-

bank.

(62) " Tertiary ' Leaf-beds of the Isle of Mull"— ' Quart.

Journ. Geol. Soc./ vol vii. Edward Forbes.

(63) ' The Geology of England and Wales.' Horace B.

Woodward.

CHAPTER XXI.

THE QUATERNARY PERIOD.

THE POST-PLIOCENE PERIOD.

Later than any of the Tertiary formations are various de-
tached and more or less superficial accumulations, which are
generally spoken of as the Post-Tertiary formations, in accord-
ance with the nomenclature of Sir Charles Lyell — or as the
Quaternary formations, in accordance with the general usage
of Continental geologists. In all these formations we meet
with no Mollusca except such as are now alive — with the
partial and very limited exception of some of the oldest de-
posits of this period, in which a few of the shells occasionally
belong to the species not known to be in existence at the pres-
ent day. Whilst the Shell-fish of the Quaternary deposits are,
generally speaking, identical with existing forms, the Mammals
are sometimes referable to living, sometimes to extinct species.
In accordance with this, the Quaternary formations are divided
into two groups: (i) The Post-Pliocene, in which the shells are
almost invariably referable to existing species, but some of the
Mammals are extinct; and (2) the Recent, in which the shells
and the Mammals alike belong to existing species. The Post-
Pliocene deposits are often spoken of as the Pleistocene forma-
tions (Gr. pleistos, most; kainos, new or recent), in allusion to

THE QUATERNARY PERIOD. 347

the fact that the great majority of the living beings of this
period belong to the species characteristic of the " new " or
Recent period.

The Recent deposits, though of the highest possible interest,
do not properly concern the palaeontologist strictly so-called,
but the zoologist, since they contain the remains of none but
existing animals. They are " Pre-historic," but they belong
entirely to the existing terrestrial order. The Post-Pliocene
deposits, on the other hand, contain the remains of various
extinct Mammals ; and though Man undoubtedly existed in,
at any rate, the later portion of this period, if not through-
out the whole of it, they properly form part of the domain of
the palaeontologist.

The Post-Pliocene deposits are extremely varied, and very
widely distributed ; and owing to the mode of their occurrence,
the ordinary geological tests of age are in their case but very
partially available. The subject of the classification of these
deposits is therefore an extremely complicated one ; and as
regards the age of even some of the most important of them,
there still exists considerable difference of opinion. For our
present purpose, it will be convenient to adopt a classifica-
tion of the Post-Pliocene deposits founded on the relations
which they bear in time to the great " Ice-age " or " Glacial
period;" though it is not pretended that our present knowl-
edge is sufficient to render such a classification more than a
provisional one.

In the early Tertiary period, as we have seen, the climate of
the northern hemisphere, as shown by the Eocene animals and
plants, was very much hotter than it is at present — partaking,
indeed, of a sub-tropical character. In the Middle Tertiary or
Miocene period, the temperature, though not so high, was still
much warmer than that now enjoyed by the northern hemi-
sphere ; and we know that the plants of temperate regions at
this time flourished within the Arctic circle. In the later
Tertiary or Pliocene period, again, there is evidence that the
northern hemisphere underwent a further progressive diminu-
tion of temperature ; though the climate of Europe generally
seems at the close of the Tertiary period to have been if any-
thing warmer, or at any rate not colder, than it is at the present
day. With the commencement of the Quaternary period,
however, this diminution of temperature became more de-
cided ; and beginning with a temperate climate, we find the
greater portion of the northern hemisphere to become gradu-

348 HISTORICAL PALAEONTOLOGY.

ally subjected to all the rigours of intense Arctic cold. All
the mountainous regions of Northern and Central Europe, of
Britain, and of North America, became the nurseries of huge
ice-streams, and large areas of the land appear to have been
covered with a continuous ice-sheet. The Arctic conditions of
this, the well-known " Glacial period," relaxed more than once,
and were more than once re-established with lesser intensity.
Finally, a gradual but steadily progressive amelioration of tem-
perature took place; the ice slowly gave way, and ultimately
disappeared altogether ; and the climate once more became
temperate, except in high northern latitudes.

The changes of temperature sketched out above took place
slowly and gradually, and occupied the whole of the Post-
Pliocene period. In each of the three periods marked out by
these changes — in the early temperate, the central cold, and
the later temperate period — certain deposits were laid down
over the surface of the northern hemisphere; and these de-
posits collectively constitute the Post-Pliocene formations.
Hence we may conveniently classify all the accumulations of
this age under the heads of (i) Pre-Glacial deposits, (2) Glacial
deposits, and (3) Post-Glacial deposits, according as they were
formed before, during, or after the " Glacial period." It can-
not by any means be asserted that we can definitely fix the
precise relations in time of all the Post-Pliocene deposits to the
Glacial period. On the contrary, there are some which hold a
very disputed position as regards this point; and there are
others which do not admit of definite allocation in this manner
at all, in consequence of their occurrence in regions where no
" Glacial Period " is known to have been established. For
our present purpose, however, dealing as we shall have to do
principally with the northern hemisphere, the above classifi-
cation, with all its defects, has greater advantages than any
other that has been yet proposed.

I. PRE-GLACIAL DEPOSITS. — The chief pre-glacial deposit of
Britain is found on the Norwalk coast, reposing upon the Newer
Pliocene (Norwich Crag), and consists of an ancient land-sur-
face which is known as the " Cromer Forest-bed."

This consists of an ancient soil, having embedded in it the
stumps of many trees, still in an erect position, with remains
of living plants, and the bones of recent extinct quadru-
peds. It is overlaid by fresh-water and marine beds, all the
shells of which belong to existing species, and it is finally sur-

THE QUATERNARY PERIOD. 349

mounted by true "glacial drift." While all the shells and
plants of the Cromer Forest-bed and its associated strata belong
to existing species, the Mammals are partly living, partly ex-
tinct. Thus we find the existing Wolf (Canis lupus), Red
Deer (Cervus elaphus), Roebuck (Cervus capreolus), Mole
(Talpa Euro pact), and Beaver (Castor fiber), living in .western
England side by side with the Hippopotamus major, Elephas
antiquus, Elephas meridionalis, Rhinoceros Etruscus, and R.
megarhinus of the Pliocene period, which are not only extinct,
but imply an at any rate moderately warm climate. Besides
the above, the Forest-bed has yielded the remains of several
extinct species of Deer, of the great extinct Beaver (Trogon-
therium Cuvieri), of the Caledonian Bull or " Urus " (Bos
priinigcnius) , and of a Horse (Equus fossilis), little if at all
distinguishable from the existing form.

The so-called " Bridlington Crag " of Yorkshire, and the
" Chillesford Beds " of Suffolk, are probably to be regarded as
also belonging to this period; though many of the shells which
they contain are of an Arctic character, and would indicate
that they were deposited in the commencement of the Glacial
period itself. Owing, however, to the fact that a few of the
shells of these deposits are known to occur in a living con-
dition, these, and some other similar accumulations, are some-
times considered as referable to the Pliocene period.

II. GLACIAL DEPOSITS. — Under this head is included a
great series of deposits which are widely spread over both
Europe and America, and which were formed at a time when
the climate of these countries was very much colder than it is
at present, and approached more or less closely to what we see
at the present day in the Arctic regions. These deposits are
known by the general name of the Glacial deposits, or by the
more specialized names of the Drift, the Northern Drift, the
Boulder-clay, the Till, &c.

These glacial deposits are found in Britain as far south as
the Thames, over the whole of Northern Europe, in all the
more elevated portions of Southern and Central Europe, and
over the whole of North America, as far south as the 3Qth
parallel. They generally occur as sands, clays, and gravels,
spread in widely-extended sheets over all the geological forma-
tions alike, except the most recent, and are commonly spoken
o'f under the general term of " Glacial drift." They vary much

350 HISTORICAL PALAEONTOLOGY.

in their exact nature in different districts, but they universally
consist of one, or all, of the following members : —

1. Unstratified clays,, or loams, containing numerous angular
or sub-angular blocks of stone, which have often been trans-
ported for a greater or less distance from their parent rock,
and which often exhibit polished, grooved, or striated surfaces.
These beds are what is called Boulder-clay, or Till.

2. Sands, gravels, and clays, often more or less regularly
stratified, but containing erratic blocks, often of large size, and
with their edges unworn, derived from considerable distances
from the place where they are now found. In these beds it is
not at all uncommon to find fossil shells ; and these, though of
existing species, are generally of an Arctic character, compris-
ing a greater or less number of forms which are now exclusively
found in the icy waters of the Arctic seas. These beds are
often spoken of as " Stratified Drift."

3. Stratified sands and gravels, in which the pebbles are
worn and rounded, and which have been produced by a re-
arrangement of ordinary glacial beds by the sea. These beds
are commonly known as " Drift-gravels," or " Regenerated
Drift."

Some of the last-mentioned of these are doubtless post-
glacial; but, in the absence of fossils, it is often impossible to
arrive at a positive opinion as to the precise age of superficial
accumulations of this nature. It is also the opinion of high
authorities that a considerable number of the so-called " cave-
deposits," with the bones of extinct Mammals, truly belong to
the Glacial period, being formed during warm intervals when
the severity of the Arctic cold had become relaxed. It is
further believed that some, at any rate, of the so-called "high-
level " river-gravels and " brick-earths " have likewise been
deposited during mild or warm intervals in the great age of
ice ; and in two or three instances this has apparently been
demonstrated — deposits of this nature, with the bones of ex-
tinct animals and the implements of man, having been shown
to be overlaid by true Boulder-clay.

The fossils of the undoubted Glacial deposits are principally
shells, which are found in great numbers in certain localities,
sometimes with Foraminifera, the bivalved cases of Ostracode
Crustaceans, &c. Whilst some of the shells of the "Drift"

THE QUATERNARY PERIOD. 351

are such as now live in the seas of temperate regions, others,
as previously remarked, are such as are now only known to
live in the seas of high latitudes; and these therefore afford
unquestionable evidence of cold conditions. Amongst these
Arctic forms of shells which characterize the Glacial beds
may be mentioned Pecten Islandicus (fig. 254), Pecten Grccn-
landicus. Scalaria Grccnlandica, Leda truncata, Astarte borealis,
Tcllina proximo, Natica claitsa. &c.

Fig. 254.— Left valve of Pecten Islandicus. Glacial and Recent.

III. POST-GLACIAL DEPOSITS. — As the intense cold of the
Glacial period became gradually mitigated, and temperate
conditions of the climate were once more re-established, various
deposits were formed in the northern hemisphere, which are
found to contain the remains of extinct Mammals, and which,
therefore, are clearly of Post-Pliocene age. To these deposits
the general name of Post-GIacial formations is given ; but it is
obvious that, from the nature of the case, and with our present
limited knowledge, we cannot draw a rigid line of demarcation
between the deposits formed toward the close of the Glacial
period, or during warm " Interglacial " periods, and those laid
down after the ice had fairly disappeared. Indeed it is ex-
tremely improbable that any such rigid line of demarcation

352 HISTORICAL PALEONTOLOGY.

should ever have existed ; and it is far more likely that the
Glacial and Post-Glacial periods, and their corresponding de-
posits, shade into one another by an imperceptible gradation.
Accepting this reservation, we may group together, under the
general head of " Post-Glacial Deposits," most of the so-called
" Valley-gravels," " Brick-earths," and " Cave-deposits," to-
gether with some " raised beaches " and various deposits of
peat. Though not strictly within the compass of this work,
a few words may be said here as to the origin and mode
of formation of the Brick-earths, Valley-gravels, and Cave-
deposits, as the subject will thus be rendered more clearly
intelligible.

Every river produces at the present day beds of fine mud
and loam, and accumulations of gravel, which it deposits at
various parts of its course — the gravel generally occupying the
lowest position, and the finer sands and mud coming above.
Numerous deposits of a similar nature are found in most
countries in various localities, and at various heights above
the present channels of our rivers. Many of these fluviatile
(Lat. fluvius, a river) deposits consist of fine loam, worked for
brick-making, and known as " Brick-earths ;" and they have
yielded the remains of numerous extinct Mammals, of which
the Mammoth (Elcphas primigenius} is the most abundant.
In the valley of the Rhine these fluviatile loams (known as
"Loess") attain a thickness of several hundred feet, and con-
tain land and fresh-water shells of existing species. With
these occur the remains of Mammals, such as the Mammoth
and Woolly Rhinoceros. Many of these Brick-earths are
undoubtedly Post-Glacial, but others seem to be clearly " inter-
glacial ;" and instances have recently been brought forward in
which deposits of Brick-earth containing bones and sliells of
fresh-water Molluscs have been found to be overlaid by regu-
lar unstratified boulder-clay.

The so-called " Valley-gravels," like the Brick-earths, are
fluviatile deposits, but are of a coarser nature, consisting of
sands and gravels. Every river gives origin to deposits of
this kind at different points along the course of its valley;
and it is not uncommon to find that there exist in the valley
of a single river two or more sets of these gravel-beds, formed
by -the river itself, but formed at times when the river ran
at different levels, and therefore formed at different periods.
These different accumulations are known as the " high-level "
and " low-level " gravels ; and a reference to the accompany-

THE QUATERNARY PERIOD. 353

ing diagram will explain the origin and nature of these de-
posits (fig. 255). When a river begins to occupy a particular
line of drainage, and to form its own channel, it will deposit
fluviatile sands and gravels along its sides. As it goes on
deepening the bed or valley through which it flows, it will
deposit other fluviatile strata at a lower level besides its new
bed. In this way have arisen the terms " high-level " and
" low-level " gravels. We find, for instances, a modern river
flowing through a valley which it has to a great extent or
entirely formed itself; by the side of its immediate channel

Fig. 255.— Recent and Post-Pliocene Alluvial Deposits. 1, Peat of the recent period ;
2, Gravel of the modern river ; 2', Loam of the modern river ; 3, Lower-level valley-
gravel with bones of extinct Mammals (Post-Pliocene) ; 3', Loam of the same age as 3;
4, Higher-level valley-gravel (Post-Pliocene) ; 4'. Loam of the same age as 4 ; 5, Upland
gravel of various kinds (often glacial drift) ; 6, Older rocks. (After Sir Charles Lyell.)

we may find gravels, sand, and loam (fig. 255, 2 2') deposited
by the river flowing in its present bed. These are recent
fluviatile or alluvial deposits. At some distance from the
present bed of the river, and at a higher level, we may find
other sands and gravels, quite like the recent ones in charac-
ter and origin, but formed at a time when the stream flowed
at a higher level, and before it had excavated its valley to its
present depth. These (fig. 255, 3 3') are the so-called " low-
level gravels " of a river. At a still higher level, and still
farther removed from the present bed of the river, we may
find another terrace, composed of just the same materials as
the lower one, but formed at a still earlier period, when the
excavation of the valley had proceeded to a much less extent.
These (fig. 255, 4 4') are the so-called "high-level gravels"
of a river, and there may be one or more terraces of these.

The important fact to remember about these fluviatile de-
posits is this — that here the ordinary geological rule is reversed.
The high-level gravels are, of course, the highest, so far as
their actual elevation above the sea is concerned; but geo-
23

354 HISTORICAL PALAEONTOLOGY.

logically the lowest, since they are obviously much older than
the low-level gravels, as these are than the recent gravels.
How much older the high-level gravels may be than the low-
level ones, it is impossible to say. They occur at heights
varying from 10 to 100 feet above the present river-chan-
nels, and they are therefore older than the recent gravels
by the time required by the river to dig out its own bed to
this depth. How long this period may be, our data do not
enable us to determine accurately ; but if we are to calculate
from the observed rate of erosion of the actually existing
rivers, the period between the different valley-gravels must
be a very long one.

The lowest or recent fluviatile deposits which occur beside
the bed of the present river, are referable to the Recent period,
as they contain the remains of none but living Mammals. The
two other sets of gravels are Post-Pliocene, as they contain
the bones of extinct Mammals, mixed with land and fresh-
water shells of existing species. Among the more important
extinct Mammals of the low-level and high-level valley-gravels
may be mentioned the Elephas aiitiquus, the Mammoth (Ele-
phas primigenius}, the Woolly Rhinoceros (R. ticJwrhinus), the
Hippopotamus, the Cave-lion, and the Cave-bear. Along
with these are found unquestionable traces of the existence
of Man, in the form of rude flint implements of undoubted
human workmanship.

The so-called " Cave-deposits," again, though exhibiting
peculiarities due to the fact of their occurrence in caverns or
fissures in the rocks, are in many respects essentially similar
to the olde,r valley-gravels. Caves, in the great majority of
instances, occur in limestone. When this is not the case, it
will generally be found that they occur along lines of sea-coast,
or along lines which can be shown to have anciently formed
the coast-line. There are many caves, however, in the making
of which it can be shown that the sea has had no hand; and
these are most of the caves of limestone districts. These owe
their origin to the solvent action upon lime of water holding
carbonic acid in solution. The rain which falls upon a lime-
stone district absorbs a certain amount of carbonic acid from
the air, or from the soil. It then percolates through the rock,
generally along the lines of jointing so characteristic of lime-
stones, and in its progress it dissolves and carries off a certain
quantity of carbonate of lime. In this way, the natural joints
and fissures in the rock are widened, as can be seen at the

THE QUATERNARY PERIOD. 355

present day in any or all limestone districts. By a continu-
ance of this action for a sufficient length of time, caves may
ultimately be produced. Nothing, also, is commoner in a
limestone district than for the natural drainage to take the
line of some fissure, dissolving the rock in its course. In this
way we constantly meet in limestone districts with springs
issuing from the limestone rock — sometimes as large rivers —
the waters of which are charged with carbonate of lime, ob-
tained by the solution of the sides of the fissure through which
the waters have flowed. By these and similar actions, every
district in which limestones are extensively developed will be
found to exhibit a number of natural caves, rents, or fissures.
The first element, therefore, in the production of cave-deposits,
is the existence of a period in which limestone rocks were
largely dissolved, and caves were formed in consequence of
the then existing drainage taking the lime of some fissure.

Secondly, there must have been a period in which various
deposits were accumulated in the caves thus formed. These
cavern-deposits are of various nature, consisting of mud,
loam, gravel, or breccias of different kinds. In all cases, these
materials have been introduced into the cave at some period
subsequent to, or contemporaneous with, the formation of the
cave. Sometimes the cave communicates with the surface by
a fissure through which sand, gravel, &c., may be washed by
rains or by floods from some neighboring river. Sometimes
the cave has been the bed of an ancient stream, and the de-
posits have been formed as are fluviatile deposits at the surface.
Or, again, the river has formerly flowed at a greater elevation
than it does at present, and the cave has been filled with
fluviatile deposits by the river at a time prior to the excava-
tion of its bed to the present depth (fig. 256). In this last
case, the cave-deposits obviously bear exactly the same rela-
tion in point of antiquity to recent deposits, as do the low-
level and high-level valley-gravels to recent river-gravels. In
any case, it is necessary for the physical geography of the dis-
trict to change to some extent, in order that the cave-deposits
should be preserved. If the materials have been introduced
by a fissure, the cave will probably become ultimately filled
to the roof, and the aperture of admission thus blocked up.
If a river has flowed through the cave, the surface configura-
tion of the district must be altered so far as to divert the river
into a new channel. And if the cave is placed in the side of

356

HISTORICAL PALEONTOLOGY.

a river-valley, as in fig. 256, the river must have excavated
its channel to such a depth that it can no longer wash out the
contents of a cave even in high floods.

If the cave be entirely filled, the included deposits generally
get more or less completely cemented together by the percola-
tion through them of water holding carbonate of lime in solu-
tion. If the cave is only partially filled, the dropping of water
from the roof holding lime in solution, and its subsequent

Fig. 256.— Diagrammatic section across a river-valley and cave, a a. Recent valley-
graves near the channel (b) of the existing river ; c, Cavern, party filled with cave-
earth ; d d, High-level gravels, filling fissures in the limestone, which perhaps com-
municate in some instances with the cave, and form a channel by which materials of
various kinds were introduced into it ; e e, Inclined beds of limestone.

evaporation, would lead to the formation over the deposits
below of a layer of stalagmite, perhaps several inches, or even
feet, in thickness. In this way cave-deposits, with their con-
tained remains, may be hermetically sealed up and preserved
without injury for an altogether indefinite period of time

In all caves in limestone in which deposits containing bones
are found, we have then evidence of three principal sets of
changes. (i.) A period during which the cave was slowly
hollowed out by the percolation of acidulated water; (2.) A
period in which the cave became the channel of an engulfed
river, or otherwise came to form part of the general drainage-
system of the district; (3.) A period in which the cave was
inhabited by various animals.

As a typical example of a cave with fossiliferous Post-
Pliocene deposits, we may take Kent's Cavern, near Torquay,
in which a systematic and careful examination has revealed the
following sequence of accumulations in descending order : —

(a) Large blocks of limestone, which lie on the floor of the
cave, having fallen from the roof, and which are sometimes
cemented together by stalagmite,

FAUNA OF THE POST-PLIOCENE. 357

(£) A layer of black mould, from three to twelve inches
thick, with human bones, fragments of pottery, stone and
bronze implements, and the bones of animals now living in
Britain. This, therefore, is a recent deposit.

(c) A layer of stalagmite, from sixteen to twenty inches
thick, but sometimes as much as five feet, containing the bones
of Man, together with those of extinct Post-Pliocene Mammals.

(d) A bed of red cave-earth, sometimes four feet in thick-
ness, with numerous bones of extinct Mammals (Mammoth,
Cave-bear, &c.), together with human implements of flint and
horn.

O) A second bed of stalagmite, in places twelve feet in
thickness, with bones of the Cave-bear.

(/) A red-loam and cave-breccia, with remains of the Cave-
bear and human implements.
t

The most important Mammals which are found in cave-
deposits in Europe generally, are the Cave-bear, the Cave-lion,
the Cave-hyaena, the Reindeer, the Musk-ox, the Glutton, and
the Lemming — of which the first three are probably identical
with existing forms, and the remainder are certainly so — to-
gether with the Mammoth and the Woolly Rhinoceros, which
are undoubtedly extinct. Along with these are found the
implements, and in some cases the bones, of Man himself, in
such a manner as to render it absolutely certain that an early
race of men was truly contemporaneous in Western Europe
with the animals above mentioned.

IV. UNCLASSIFIED POST-PLIOCENE DEPOSITS. — Apart from
any of the afore-mentioned deposits, there occur other accumu-
lations— sometimes superficial, sometimes in caves — which are
found in regions where a " Glacial period " has not been fully
demonstrated, or where such did not take place; and which,
therefore, are not amenable to the above classification. The
most important of these are known to occur in South America
and Australia ; and though their numerous extinct Mammalia
place their reference to the Post-Pliocene period beyond
doubt, their relations to the glacial period and its deposits in
the northern hemisphere have not been precisely determined.

358 HISTORICAL PALEONTOLOGY.

CHAPTER XXII.
THE POST-PLIOCENE PERIOD.— Continued.

As regards the life of the Post-Pliocene period, we have, in
the first place, to notice the effect produced throughout the
northern hemisphere by the gradual supervention of the Glacial
period. Previous to this the climate must have been temper-
ate or warm-temperate; but as the cold gradually came on,
two results were produced as regards living beings of the
area thus affected. In the first place, all those Mammals
which, like the Mammoth, the Woolly Rhinoceros, the Lion,
the Hysena, and the Hippopotamus, require, at any rate, moder-
ately warm conditions, would be forced to migrate southwards
to regions not affected by the new state of things. In the
second place, Mammals previously inhabiting higher latitudes,
such as the Reindeer, the Musk-ox, and the Lemming, would
be enabled by the increasing cold to migrate southwards, and
to invade provinces previously occupied by the Elephant and
the Rhinoceros. A precisely similar, but more slowly-executed
process, must have taken place in the sea, the northern Mol-
lusca moving southwards as the arctic conditions of the Glacial
period became established, whilst the forms proper to temperate
seas receded. As regards the readily locomotive Mammals,
also, it is probable that this process was carried on repeatedly
in a partial manner, the southern and northern forms alternately
fluctuating backwards and forwards over the same area, in ac-
cordance with the fluctuations of temperature which have been
shown by Mr. James Geikie to have characterized the Glacial
period as a whole. We can thus readily account for the inter-
mixture which is sometimes found of northern and southern types
of Mammalia in the same deposits, or in deposits apparently
synchronous, and within a single district. Lastly, at the final
close of the arctic cold of the Glacial period, and the re-estab-
lishment of temperate conditions over the northern hemisphere,
a reversal of the original process took place — the northern
Mammals retiring within their ancient limits, and the southern
forms pressing northwards and reoccupying their original
domains.

FAUNA OF THE POST-PLIOCENE. 359

The Invertebrate animals of the Post-Pliocene deposits re-
quire no further mention — all the known forms, except a few
of the shells in the lowest beds of the formation, being iden-
tical with species now in existence upon the globe. The only
point of importance in this connection has been previously
noticed — namely, that in the true Glacial deposits themselves
a considerable number of the shells belong to northern or
Arctic types.

As regards the Vertebrate animals of the period, no extinct
forms of Fishes, Amphibians, or Reptiles are known to occur,
but we meet with both extinct Birds and extinct Mammals.
The remains of the former are of great interest, as indicating
the existence during Post-Pliocene times, at widely remote
points of the southern hemisphere, of various wingless, and for
the most part gigantic, Birds. All the great wingless Birds of
the order Cursores which are known as existing at the pres-
ent day upon the globe, are restricted to regions which are
either wholly or in great part south of the equator. Thus the
true Ostriches are African ; the Rheas are South American ;
the Emeus are Australian ; the Cassowaries are confined to
Northern Australia, Papua, and the Indian Archipelago ; the
species of Apteryx are natives of New Zealand ; and the
Dodo and Solitaire (wingless, though probably not true Cur-
sores'), both of which have been exterminated within histor-
ical times, were inhabitants of the islands of Mauritius and
Rodriguez, in the Indian Ocean. In view of these facts, it
is noteworthy that, so far as known, all the Cursorial Birds
of the Post-Pliocene period should have been confined to the
same hemisphere as that inhabited by the living representatives
of the order. It is still further interesting to notice that the
extinct forms in question are only found in geographical prov-
inces which are now, or have been within historical times, inhab-
ited by similar types. The greater number of the remains of
these have been discovered in New Zealand, where there now
live several species of the curious wingless genus Apteryx; and
they have been referred by Professor Owen to several generic
groups, of which Dinoniis is the most important (fig 257).
Fourteen species of Dinoniis have been described by the dis-
tinguished palaeontologist just mentioned, all of them being
large wingless birds of the type of the existing Ostrich, having
enormous powerful hind-limbs adapted for running, but with
the wings wholly rudimentary, and the breast-bone devoid of
the keel or ridge which characterizes this bone in all birds

360 HISTORICAL PALEONTOLOGY.

which fly. The largest species is the Dinornis giganteus, one
of the most gigantic of living or fossil birds, the shank (tibia)
measuring a yard in length, and the total height being at least
ten feet. Another species, the Dinornis elcphantopus (fig. 257),
though not standing more than about six feet in height, was
of an even more ponderous construction — " the framework

Fig. 257. — Skeleton of Dinornis elephantopus, greatly reduced. Post-Pliocene,
New Zealand. (After Owen.)

of the skeleton being the most massive of any in the whole
class of Birds," whilst " the toe-bones almost rival those of the
Elephant" (Owen). The feet in Dinornis were furnished with
three toes, and are of interest as presenting us with an un-
doubted Bird big enough to produce the largest of the foot-
prints of the Triassic Sandstones of Connecticut. New Zea-

FAUNA OF THE POST-PLIOCENE. 361

land has now been so far explored, that it seems questionable
if it can retain in its recesses any living example of Dinornis;
but it is certain that species of this genus were alive during the
human period, and survived up to quite a recent date. Not
only are the bones very numerous in certain localities, but
they are found in the most recent and superficial deposits, and
they still contain a considerable proportion of animal matter;
whilst in some instances bones have been found with the
feathers attached, or with the horny skin of the legs still ad-
hering to them. Charred bones have been found in connec-
tion with native "ovens;" and the traditions of the Maories
contain circumstantial accounts of gigantic wingless Birds, the
" Moas," which were hunted both for their flesh and their
plumage. Upon the whole, therefore, there can be no doubt
but that the Moas of New Zealand have been exterminated at
quite a recent period — perhaps within the last century — by the
unrelenting pursuit of Man, — a pursuit which their wingless
condition rendered them unable to evade.

In Madagascar, bones have been discovered of another huge
wingless Bird, which must have been as large as, or larger
than, the Dinornis giganieus, and which has been described
under the name of JEpiornis ina.viinns. With the bones have
been found eggs measuring from thirteen to fourteen inches in
diameter, and computed to have the capacity of three Ostrich
eggs. At least two other small species of ^Epiornis have been
described by Grandidier and Milne-Edwards as occurring in
Madagascar; and they consider the genus to be so closely allied
to the Dinornis of New Zealand, as to prove that these regions,
now so remote, were at one time united by land. Unlike New
Zealand, where there is the Apteryx, Madagascar is not known
to possess any living wingless Birds; but in the neighboring
island of Mauritius the wingless Dodo (Didus ineptus) has been
exterminated less than three hundred years ago; and the little
island of Rodriguez, in the same geographical province, has in
a similar period lost the equally wingless Solitaire (Pezophaps},
both of these, however, being generally referred to the Rasores.

The Mammals of the Post-Pliocene period are so numerous,
that in spite of the many points of interest which they present,
only a few of the more important forms can be noticed here,
and that but briefly. The first order that claims our attention
is that of the Marsupials, the headquarters of which at the
present day is the Australian province. In Oolitic times
Europe possessed its small Marsupials, and similar forms

362

HISTORICAL PALEONTOLOGY.

existed in the same area in the Eocene and Miocene periods ;
but if size be any criterion, the culminating point in the history
of the order was attained during the Post-Pliocene period in
Australia. From deposits of
this age there has been disen-
tombed a whole series of re-
mains of extinct, and for the
most part gigantic, examples
of this group of Quadrupeds.
Not to speak of Wombats and
Phalangers, two forms stand
out prominently as represen-
tatives of the Post-Pliocene
animals of Australia. One of
these is Diprotodon (fig. 258), representing, with many differ-
ences, the well-known modern group of the Kangaroos. In
its teeth, Diprotodon shows itself to be closely allied to the

"Fig. 258.— Skull of Diprotrxton. Australia,
greatly reduced. Post- Pliocene. Australia.

Fig. 259. — Skull of Thylacoleo. Post-Pliocene. Australia. Greatly reduced.
(After Flower.)

t

living, grass-eating Kangaroos ; - but the hind-limbs were not
so disproportionately long. In size, also, Diprotodon must
have many times exceeded the dimensions of the largest of
its living successors, since the skull measures no less than
three feet in length. The other form in question is Thylacoleo
(fig. 259), which is believed by Professor Owen to belong to
the same group as the existing " Native Devil " (Dasyurns) of

FAUNA OF THE POST-PLIOCENE. 363

Van Diemen's Land, and therefore to have been flesh-eating
and rapacious in its habits, through this view is not accepted
by others. The principal feature in the skull of Thylacolco is
the presence, on each side of each jaw, of a single huge tooth,
which is greatly compressed, and has a cutting edge. This
tooth is regarded by Owen as corresponding to the great cut-
ting tooth of the jaw of the typical Carnivores, but Professor
Flower considers that Thvlacoleo is rather related to the Kan-

Fig. 260. — MeyatheriumCuvieri. Post-Pliocene. South America.

garoo-rats. The size of the crown of the tooth in question is
not less than two inches and a quarter; and whether carnivor-
ous or not, it indicates an animal of a size exceeding that of
the largest of existing Lions.

The order of the Edentates, comprising the existing Sloths,
Ant-eaters, and Armadillos, and entirely restricted at the present
day to South America, Southern Asia, and Africa, is one alike
singular for the limited geographical range of its members,
their curious habits of life, and the well-marked peculiarities
of their anatomical structure. South America is the metrop-
olis of the existing forms ; and it is an interesting fact that there
flourished within Post-Pliocene times in this continent,, and to
some extent in North America also, a marvelous group of ex-
tinct Edentates, representing the living Sloths and Armadillos,
but of gigantic size. The most celebrated of these is the huge
Megatherium Cuvieri (fig. 260) of the South American Pampas.
The Megathere was a colossal Sloth-like animal which attained
a length of from twelve to eighteen feet, with bones more mas-
sive than those of the Elephant. Thus the thigh-bone is

364 HISTORICAL PALEONTOLOGY.

nearly thrice the thickness of the same bone in the largest
of existing Elephants, its circumference at its narrowest point
nearly equalling its total length ; the massive bones of the
shank (tibia and fibula) are amalgamated at their extremities;
the heel-bone (calcaneum) is nearly half a yard in length; the
haunch-bones (ilia) are from four to five feet across at their
crests; and the bodies of the vertebras at the root of the tail
are from five to seven inches in diameter, from which it has
been computed that the circumference of the tail at this part
might have been from five to six feet. The length of the fore-
foot is about a yard, and the toes are armed with powerful
curved claws. It is known now that the Megathere, in spite
of its enormous weight and ponderous construction, walked,
like the existing Ant-eaters and Sloths, upon the outside edge
of the fore-feet, with the claws more or less bent inwards
towards the palm of the hand. As in the great majority of
the Edentate order, incisor and canine teeth are entirely
wanting, the front of the jaws being toothless. The jaws,
however, are furnished with five upper and four lower molar
teeth on each side. These grinding teeth are from seven to
eight inches in length, in the form of four-sided prisms, the
crowns of which are provided with well-marked transverse
ridges; and they continue to grow during the whole life of
the animal. There are indications that the snout was pro-
longed, and more or less flexible; and the tongue was prob-
ably prehensile. From the characters of the molar teeth it
is certain that the Megathere was purely herbivorous in its
habits ; and from the enormous size and weight of the body,
it is equally certain that it could not have imitated its modern
allies, the Sloths, in the feat of climbing, back downwards,
amongst the trees. It is clear, therefore, that the Megathere
sought its sustenance upon the ground ; and it was originally
supposed to have lived upon roots. By a masterly piece of
deductive reasoning, however, Professor Owen showed that
this great " Ground-Sloth " must have truly lived upon the
foliage of trees, like the existing Sloths — but with this differ-
ence, that instead of climbing amongst the branches, it actually
uprooted the tree bodily. In this tour de force, the animal
sat upon its huge haunches and mighty tail, as on a tripod,
and then grasping the trunk with its powerful arms, either
wrenched it up by the roots or broke it short off above the
ground. Marvellous as this may seem, it can be shown that
every detail in the skeleton of the Megathere accords with the

FAUNA OF THE POST-PLIOCENE.

365

supposition that it obtained its food in this way. Similar
habits were followed by the allied Mylodon (fig. 261), another
of the great " Ground-Sloths," which inhabited South America
during the Post-Pliocene period. In most respects, the Mylo-

Ylg. 261.— Skeleton of Mylodon robuatus. Post-Pliocene, South America.

don is very like the Megathere ; but the crowns of the molar
teeth are flat instead of being ridged. The nearly-related
genus Megalonyx, unlike the Megathere, but like the Mylodon,
extended its range northwards as far as the United States.

Fig. 262.— Skeleton of Gl>/ptodon clavtpes. Post-Pliocene, South America.

Just as the Sloths of the present day were formerly repre-
sented in the same geographical area by the gigantic Megathe-

366

HISTORICAL PALEONTOLOGY.

roids, so the little banded and cuirassed Armadillos of South
America were formerly represented by gigantic species, con-
stituting the genus Glyptodon. The Glyptodons (fig. 262)
differed from the living Armadillos in having no bands in
their armour, so that they must have been unable to roll
themselves up. It is rare at the present day to meet with any
Armadillo over two or three feet in length ; but the length of
the Glyptodon clavipes, from the tip of the snout to the end of
the tail, was more than nine feet.

There are no canine or incisor teeth in the Glyptodon, but
there are eight molars on each side of each jaw, and the crowns
of these are fluted and almost trilobed. The head is covered
by a helmet of bony plates, and the trunk was defended by an
armour of almost hexagonal bony pieces united by sutures, and
exhibiting special patterns of sculpturing in each species. The
tail was almost defended by a similar armour, and the vertebrae
were mostly fused together so as to form a cylindrical bony
rod. In addition to the above-mentioned forms, a number
of other Edentate animals have been discovered by the re-
searches of M. Lund in the Post-Pliocene deposits of the
Brazilian bone-caves. Amongst these are true Ant-eaters,
Armadillos, and Sloths, many of them of gigantic size, and all
specifically or generically distinct from existing forms.

Fig. 263.— Skull of the Tichorhhie Rhinoceros, the horns being wanting. One-tenth of
the natural size. Post-Pliocene deposits of Europe and Asia.

Passing over the aquatic orders of the Sirenians and Ce-
taceans, we come next to the great group of the Hoofed Quad-
rupeds, the remains of which are very abundant in Post-
Pliocene deposits both in Europe and North America.
Amongst the Odd-toed Ungulates the most important are

FAUNA OF THE POST-PLIOCENE. 367

the Rhinoceroses, of which three species are known to have
existed in Europe during the Post-Pliocene period. Two
of these are the well-known Pliocerte forms, the Rhinoceros
Etruscus and the R. megarhinus, still surviving in diminished
numbers; but the most famous is the Rhinoceros tichorhinus
(fig. 263), or so-called "Woolly Rhinoceros." This species
is known not only by innumerable bones, but also by a car-
cass, at the time of its discovery complete, which was found
embedded in the frozen soil of Siberia towards the close of
last century, and which was partly saved from destruction by
the exertions of the naturalist Pallas. From this, we know
that the Tichorhine Rhinoceros, like its associate the Mam-
moth, was provided with a coating of hair, and therefore was
enabled to endure a more severe climate than any existing
species. The skin was not thrown into the folds which char-
acterize most of the existing forms; and the technical name
of the species refers to the fact that the nostrils were com-
pletely separated by a bony partition. The head carried two
horns, placed one behind the other, the front one being un-
usually large. As regards its geographical range, the Woolly
Rhinoceros is found in Europe in vast numbers north of the
Alps and Pyrenees, and it also abounded in Siberia; so that
it would appear to be a distinctly northern form, and to have
been adapted for a temperate climate. It is not known to
occur in Pliocene deposits, but it makes its first appearance
in the Pre-Glacial deposits, surviving the Glacial period, and
being found in abundance in Post-Glacial accumulations. It
was undoubtedly a contemporary of the earlier races of men
in Western Europe ; and it may perhaps be regarded as being
the actual substantial kernel of some of the " Dragons " of
fable.

The only other Odd-toed Ungulate which needs notice is
the so-called Equus fossilis of the Post-Pliocene of Europe.
This made its appearance before the Glacial period, and ap-
pears to be in reality identical with the existing Horse (Equus
caballus}. True Horses also occur in the Post-Pliocene of
North America ; but, from some cause or another, they must
have been exterminated before historic times.

Amongst the Even-toed Ungulates, the great Hippopotamus
major of the Pliocene still continued to exist in Post-Pliocene
times in Western Europe; and the existing Wild Boar (Sus
scrofa}, the parent of our domestic breeds of Pigs, appeared
for the first time. The Old World possessed extinct repre-

368

HISTORICAL PALEONTOLOGY.

sentatives of its existing Camels, and lost types of the living
Llamas inhabited South America. Amongst the Deer, the
Post-Pliocene accumulations have yielded the remains of
various living species, such as the Red Deer (Cervus elaphus),
the Reindeer (Cervus tarandus}, the Moose or Elk (Alces
malchis}, and the Roebuck (Cervus caprcolus}, together with
a number of extinct forms. Among the latter, the great
"Irish Elk" (Cervus megaceros} is justly celebrated both for

Fig. 264.— Skeleton of the " Irish Elk " (Cervus megaceros.) Post-Pliocene, Britain.

its size and for the number and excellent preservation of its
discovered remains. This extinct species (fig. 264) has been
found principally in peat-mosses and Post-Pliocene lake-

FAUNA OF THE POST-PLIOCENE 369

deposits, and is remarkable for the enormous size of the
spreading antlers, which are widened out towards their ex-
tremities, and attain an expanse of over ten feet from tip to
tip. It is not a genuine Elk, but is intermediate between
the Reindeer and the Fallow-deer. Among the existing Deer

Fig. 265 .--Skull of the Urus (Bos primigeniua) . Post-Pliocene and Recent.
(After Owen.)

of the Post-Pliocene, the most noticeable is the Reindeer,
an essentially northern type, existing at the present day in
Northern Europe, and also (under the name of- the "Caribou")
in North- America. When the cold of the Glacial period be-
came established, this boreal species was enabled to invade
Central and Western Europe in great herds, and its remains
are found abundantly in cave-earths and other Post-Pliocene
deposits as far south as the Pyrenees.

In addition to the above, the Post-Pliocene deposits of
Europe and North America have yielded the remains of vari-
ous Sheep and Oxen. One of the most interesting of the
latter is the "Urus" or Wild Bull (Bos primigenius., fig. 265),
which, though much larger than any of the existing forms, is
believed to be specifically undistinguishable from the domes-
tic Ox (Bos taurus}, and to be possibly the ancestor of some
of the larger European varieties of oxen. In the earlier part
of its existence the Urus ranged over Europe and Britain in
company with the Woolly Rhinoceros and the Mammoth ; but
it long survived these, and does not appear to have been
24

370 HISTORICAL PALAEONTOLOGY.

finally exterminated till about the twelfth century. Another
remarkable member of the Post-Pliocene Cattle, also to be-
gin with an associate of the Mammoth and Rhinoceros, is
the European Bison or "Aurochs" (Bison prisons}. This
" maned " ox formerly abounded in Europe in Post-Glacial
times, and was not rare even in the later periods of the
Roman empire, though much diminished in numbers , and
driven back into the wilder and more inaccessible parts of the
country. At present this fine species has been so nearly
exterminated that it no longer exists in Europe save in
Lithuania, where its preservation has been secured by rigid
protective laws. Lastly, the Post-Pliocene deposits have
yielded the remains of the singular living animals which is
known as the Musk-ox or Musk-sheep (Ovibos moschatus).
At the present day, the Musk-ox is an inhabitant of the
" barren grounds " of Arctic America, and it is remarkable for
the great length of its hair. It is, like the Reindeer, a dis-
tinctively northern animal ; but it enjoyed during the Glacial
period a much wider range than it has at the present day, the
conditions suitable for its existence being then extended over
a considerable portion of the northern hemisphere. Thus
remains of the Musk-Ox are found in greater or less abun-
dance in Post-Pliocene deposits over a great part of Europe,
extending even to the south of France ; and closely-related
forms are found in similar deposits in the United States.

Coming to the Proboscideans, we find that the Mastodons
seem to have disappeared in Europe at the close of the
Pliocene period, or at the very commencement of the Post-
Pliocene. In the New World, on the other hand, a species of
Mastodon (M. Americanus or M. Ohioticus} is found abun-
dantly in deposits of Post-Pliocene age, from Canada to
Texas. Very perfect skeletons of this species have been
exhumed from morasses and swamps, and large individuals
attained a length (exclusive of the tusks) of seventeen feet and
a height of eleven feet, the tusks being twelve feet in length.
Remains of Elephants are also abundant in the Post-pliocene
deposits of both the Old and the New World. Amongst these,
we find in Europe the two familiar Pliocene species, E. ineri-
dionalis and E. antiquus, still surviving, but in diminished
numbers. With these are found in vast abundance the re-
mains of the characteristic Elephant of the Post-Pliocene, the
well-known "Mammoth" (Elephas priniigenius'), which is ac-
companied in North America by the nearly-allied, but more

FAUNA OF THE POST-PLIOCENE.

37i

southern species, me Elephas Americanus. The Mammoth (fig.
266) is considerably larger than the largest of the living Ele-

phants, the skeleton being over sixteen feet in length, exclusive
of the tusks, and over nine feet in height. The tusks are bent
almost into a circle, and are sometimes twelve feet in length,

372

HISTORICAL PALAEONTOLOGY.

measured along their curvature. In the frozen soil of Siberia
several carcasses of the Mammoth have been discovered with
the flesh and skin still attached to the bones, the most cele-
brated of these being a Mammoth which was discovered at the
beginning of this century at the mouth of the Lena, on the borders
of the Frozen Sea, and the skeleton of which is now preserved
at St. Petersburg (fig. 266). From the occurrence of the remains
of the Mammoth in vast numbers in Siberia, it might have been
safely inferred that this ancient Elephant was able to endure a far
more rigorous climate than its existing congeners. This infer-
ence has, however, been rendered a certainty by the specimens
just referred to, which show that the Mammoth was protected

Fig. 267.— Molar tooth of the Mammoth (Elephaa primigenlus'), upper jaw, right side,
one-third of the naturai size, a, Grinding surface ; 6, Side view. Post-Pliocene.

against the cold by a thick coat of reddish-brown wool, some
nine or ten inches long, interspersed with strong, coarse black
hair more than a foot in length. The teeth of the Mammoth
(fig. 267) are of the type of those of the existing Indian Ele-
phant, and are found in immense numbers in certain localities.
The Mammoth was essentially northern in its distribution,
never passing south of a line drawn through the Pyrenees, the
Alps, the northern shores of the Caspian, Lake Baikal, Kam-
schatka, and the Stanovi Mountains (Dawkins). It occurs in
the Pre-Glacial forest-bed of Cromer in Norfolk, survived the
Glacial period, and is found abundantly in Post-Glacial de-

FAUNA OF THE POST-PLIOCENE. 3%

posits in France, Germany, Britain, Russia in Europe, Asia,
and North America, being often associated with the Reindeer,
Lemming, and Musk-Ox. That it survived into the earlier
portion of the human period is unquestionable, its remains
having been found in a great number of instances associated
with implements of human manufacture; whilst in one instance
a recognizable portrait of it has been discovered, carved on
bone.

Amongst other Elephants which occur in Post-Pliocene de-
posits may be mentioned, as of special interest, the pigmy
Elephants of Malta. One of these — the Elephas Melitensis, or
so-called " Donkey-Elephant " — was not more than four and
a half feet in height. The other — the Elephas Falconeri, of
Busk — was still smaller, its average height at the withers not"
exceeding two and a half to three feet.

Whilst herbivorous animals abounded during the Post-
Pliocene, we have ample evidence of the coexistence with
them of a number of Carnivorous forms, both in the New and
the Old World. The Bears are represented in Europe by at
least three species, two of which — namely, the great Grizzly
Bear (Ursus jerox} and the smaller Brown Bear (Ursus arctos}
— are in existence at the present day. The third species is the
celebrated Cave-bear (Ursus spelaus, fig. 268), which is now

Fig. 268. — Skull of Unua spelceus. Post-Pliocene, Europe. One-sixth
of the natural size.

extinct. The Cave-bear exceeded in its dimensions the largest
of modern Bears; and its remains, as its name implies, have
been found mainly in cavern-deposits. Enormous numbers of

374 HISTORICAL PALEONTOLOGY.

this large and ferocious species must have lived in Europe in
Post-Glacial times ; and that they survived into the human
period, is clearly shown by the common association of their
bones with the implements of man. They are occasionally
accompanied by the remains of a Glutton (the Gulo sp elans'),
which does not appear to be really separable from the existing
Wolverine or Glutton of northern regions (the Gulo luscus}.
In addition, we meet with the bones of the Wolf, Fox, Weasel,
Otter, Badger, Wild Cat, Panther, Hyaena, and Lion, &c.,
together with the extinct Machairodus or " Sabre-toothed
Tiger." The only two of these that deserve further mention
are the Hyaena and the Lion. The Cave-hyaena (Hyana
spelaa, fig. 269) is regarded by high authorities as nothing
more than a variety of the living Spotted Hyaena (H. crocuta}
of South Africa. This well-known species inhabited Britain
and a considerable portion of Europe during a large part of
the Post-Pliocene period; and its remains often occur in great
abundance. Indeed, some caves, such as the Kirkdale Cavern
in Yorkshire, were dens inhabited during long periods by these
animals, and thus contain the remains of numerous individuals
and of successive generations of Hyaenas, together with in-
numerable gnawed and bitten bones of their prey. That the

Fig. 269.— Skull of Hycena spelcea, one-fourth of the natural size.
Post-Pliocene, Europe.

Cave-hyaena was a contemporary with Man in Western Europe
during Post-Glacial times is shown beyond a doubt by the
common association of its bones with human implements.

Lastly, the so-called Cave-lion (Felis Spelcea}, long supposed
to be a distinct species, has been shown to be nothing more

FAUNA OF THE POST-PLIOCENE. 375

than a large variety of the existing Lion (Pel is leo}. This
animal inhabited Britain and Western Europe in times pos-
terior to the Glacial period, and was a contemporary of the
Cave-hyaena, Cave-bear, Woolly Rhinoceros, and Mammoth.
The Cave-lion also unquestionably survived into the earlier
portion of the human period in Europe.

The Post-Pliocene deposits of Europe have further yielded
the remains of numerous Rodents— such as the Beaver, the
Northern Lemming, Marmots, Mice, Voles, Rabbits, &c. — to-
gether with the gigantic extinct Beaver known as the Trogon-
theriitiu Cuvieri (fig. 270). The great Castoroides Ohioensis of

the Post-Pliocene of North
America is also a great ex-
tinct Beaver, which reached
a length of about five feet.
Lastly, the Brazilian bone-
caves have yielded the re-
mains of numerous Rodents
of types now characteristic
of South America, such as
Guinea-pigs, Capybaras, tree-
inhabiting Porcupines, and
Coypus.

The deposits just alluded to have further yielded the
remains of various Monkeys, such as Howling Monkeys,
Squirrel Monkeys, and Marmosets, all of .which belong to the
group of Quadrumona which is now exclusively confined to
the South American continent — namely, the " Platyrhine "
Monkeys.

\\ e still have very briefly to consider the occurrence of
Man in Post-Pliocene deposits; but before doing so, it will be
well to draw attention to the evidence afforded by the Post-
Pliocene Mammals as to the climate of Western Europe at
this period. The chief point which we have to notice is, that
a considerable revolution of opinion has taken place on this
point. It was originally believed that the presence of such
animals as Elephants, Lions, the Rhinoceros, and the Hippo-
potamus afforded an irrefragable proof that the climate of
Europe must have been a warm one, at any rate during Post-
Glacial times. The existence, also, of numbers of Mammoths
in Siberia, was further supposed to indicate that this high tem-
perature extended itself very far north. Upor the whole, how-
ever, the evidence is against this view. Not only is there great

. 270.— Lower jaw of Trogontherium

376 HISTORICAL PALEONTOLOGY.

difficulty in supposing that the Arctic conditions of the Glacial
period were immediately followed by anything warmer than a
cold-temperate climate ; but there is nothing in the nature of
the Mammals themselves which would absolutely forbid their
living in a temperate climate. The Hippopotamus major, though
probably clad in hair, offers some difficulty — since, as pointed
out by Professor Busk, it must have required a climate suffi-
ciently warm to insure that the rivers were not frozen over in the
winter ; but it was probably a migratory animal, and its occur-
rence may be accounted for by this. The Wooly Rhinoceros
and the Mammoth are known with certainty to have been pro-
tected with a thick covering of wool and hair; and their ex-
tension northwards need not necessarily have been limited by
anything except the absence of a sufficiently luxuriant vege-
tation to afford them food. The great American Mastodon,
though not certainly known to have possessed a hairy covering,
has been shown to have lived upon the shoots of Spruce and
Firs, trees characteristic of temperate regions — as shown by the
undigested food which has been found with its skeleton, oc-
cupying the place of the stomach. The Lions and Hyaenas,
again, as shown by Professor Boyd Dawkins, do not indicate
necessarily a warm climate. Wherever a sufficiency of her-
bivorous animals to supply them with food can live, there they
can live also ; and they have therefore no special bearing upon
the question of climate. After a review of the whole evidence,
Professor Dawkins concludes that the nearest approach at the
present day to the Post-Pliocene climate of Western Europe
is to be found in the climate of the great Siberian plains which
stretch from the Altai Mountains to the Frozen Sea. "Covered
by impenetrable forests, for the most part of Birch, Poplar,
Larch, and Pines, and low creeping dwarf Cedars, they present
every gradation in climate from the temperate to that in which
the cold is too severe to admit of the growth of trees, which
decrease in size as the traveler advances northwards, and are
replaced by the grey mosses and lichens that cover the low
marshy 'tundras.' The maximum winter cold, registered by
Admiral Von Wrangel at Nishne Kolymsk, on the banks of
the Kolyma, is — 65° in January. ' Then breathing becomes
difficult; the Reindeer, that citizen of the Polar region, with-
draws to the deepest thicket of the forest, and stands there
motionless as if deprived of life ;' and trees burst asunder with
the cold. Throughout this area roam Elks, Black Bears,
Foxes, Sables, and Wolves, that afford subsistence to the

FAUNA OF THE POST-PLIOCENE. 377

Jakutian and Tungusian fur-hunters. In the northern part
countless herds of Reindeer, Elks, Foxes, and Wolverines
make up for the poverty of vegetation by the rich abundance
of animal life. ' Enormous flights of Swans, Geese, and Ducks
arrive in the spring, and seek deserts where they may moult
and build their nests in safety. Ptarmigans run in troops
amongst the bushes ; little Snipes are busy along the brooks
and in the morasses; the social Crows seek the neighborhood
of new habitations ; and when the sun shines in spring, one
may even sometimes hear the cheerful note of the Finch, and
in autumn that of the Thrush.' Throughout this region of
woods, a hardy, middle-sized breed of horses lives under the
mastership and care of man, and is eminently adapted to bear
the severity of the climate. . . . The only limit to their
northern range is the difficulty of obtaining food. The severity
of the winter through the southern portion of this vast wooded
area is almost compensated for by the summer heat and its
marvellous effect on vegetation." — (Dawkins, ' Monograph of
Pleistocene Mammalia.')

Finally, a few words must be said as to the occurrence of the
remains of Man in Post-Pliocene deposits. That Man existed
in Western Europe and in Britain during the Post-pliocene
period, is placed beyond a doubt by the occurrence of his bones
in deposits of this age, along with the much more frequent
occurrence of implements of human manufacture. At what
precise point of time during the Post-Pliocene period he first
made his appearance is still a matter of conjecture. Recent
researches would render it probable that the early inhabitants
of Britain and Western. Europe were witnesses of the stupend-
ous phenomena of the Glacial period ; but this cannot be said
to have been demonstrated. That Man existed in these
regions during the Post-Glacial division of Post-Pliocene time
cannot be doubted for a moment. As to the physical peculi-
arities of the ancient races that lived with the Mammoth and
the Woolly Rhinoceros, little is known compared with what
we may some day hope to know. Such information as we
have, however, based principally on the skulls of the Engis,
Neanderthal, Cro-Magnon, and Bruniquel caverns, would lead
to the conclusion that Post-Pliocene Man was in no respect
inferior in his organization to, or less highly developed than,
many existing races. All the known skulls of this period, with
the single exception of the Neanderthal cranium, are in all
respects average and normal in their characters ; and even the

378 HISTORICAL PALEONTOLOGY.

Neanderthal skull possessed a cubic capacity at least equal to
that of some existing races. The implements of Post-Pliocene
Man are exclusively of stone or bone; and the former are
invariably of rude shape and undressed. These " palaeolithic "
tools (Gr. palaios, ancient; lithos, stone) point to a very early
condition of the arts ; since the men of the earlier portion
of the Recent period, though likewise unacquainted with the
metals, were in the habit of polishing or dressing the stone
implements which they fabricated.

It is impossible here to enter further into this subject; and
it would be useless to do so without entering as well into a
consideration of the human remains of the Recent period — a
period which lies outside of the province of the present work. So
far as Post-Pliocene Man is concerned, the chief points which
the palseontological student has to remember have been else-
where summarized by the author as follows : —

1. Man unquestionably existed during the later portion of
what Sir Charles Lyell has termed the " Post-Pliocene " period.
In other words, Man's existence dates back to a time when
several remarkable Mammals, previously mentioned, had not
yet become extinct ; but he does not date back to a time
anterior to the present Mollusc an fauna.

2. The antiquity of the so-called Post-Pliocene period is
a matter which must be mainly settled by the evidence of
Geology proper, and need not be discussed here.

3. The extinct Mammals with which man coexisted in
Western Europe are mostly of large size, the most important
being the Mammoth (Elephas priniigenius}, the Woolly Rhino-
ceros (Rhinoceros tichorhinus}, the Cave-lion (Felis spelcea}, the
Cave-hyaena (Hycena sj>elaa),B.nd the Cave-bear (Ursusspelcuus).
We do not know the cause which led to the extinction of
these Mammals ; but we know that hardly any Mammalian
species has become extinct during the historical period.

4. The extinct Mammals with which man coexisted are re-
ferable in many cases to species which presumably required a
very different climate to that now prevailing in Western Europe.
How long a period, however, has been consumed in the bring-
ing about of the climatic changes thus indicated, we have no
means of calculating with any approach to accuracy.

5. Some of the deposits in which the remains of man have
been found associated with the bones of extinct Mammals, are
such as to show incontestable that great changes in the phy-
sical geography and surface-configuration of Western Europe

FAUNA OF THE POST-PLIOCENE. 379

have taken place since the period of their accumulation. \Vc
have, however, no means at present of judging of the lapse of
time thus indicated except by analogies and comparisons which
may be disputed.

6. The human implements which are associated with the
remains of extinct Mammals, themselves bear evidence of an
exceedingly barbarous condition of the human species. Post-
Pliocene or " Palaeolithic " Man was clearly unacquainted with
the use of any of the metals. Not only so, but the workman-
ship of these ancient races was much inferior to that of the
later tribes, who were also ignorant of the metals, and who
also used nothing but weapons and tools of stone, bone, &c.

7. Lastly, it is only with the human remains of the Post-
Fliocene period that the palaeontologist proper has to deal.
V hen we enter the "Recent" period, in which the remains of
Man are associated with those of existing species of Mammals,
we pass out of the region of pure palaeontology into the do-
main of the Archaeologist and the Ethnologist.

LITERATURE.

The following are some of the principal works and memoirs
to which the student may refer for information as to the Post-
Pliocene deposits and the remains which they contain, as well as
the primitive races of mankind : —

(1) 'Elements of Geology.' Lyell.

(2) ' Antiquity of Man.' Lyell.

(3) Talaeontological Memoirs.' Falconer.

(4) ' The Great Ice-age.' James Geikie.

(5) ' Manual of Palaeontology.' Owen.

(6) ' British Fossil Mammals and Birds/ Owen.

(7) ' Cave-Hunting.' Boyd Dawkins.

(8) ' Prehistoric Times.' Lubbock.

(9) ' Ancient Stone Implements.' Evans.

(10) 'Prehistoric Man.' Daniel Wilson.

(n) 'Prehistoric Races of the United States.' Foster.

(12) 'Manual of Geology.' Dana.

(13) 'Monograph of Pleistocene Mammalia.' (Palaeonto-

graphical Society). Boyd Dawkins and Sanford.

(14) ' Monograph of the Post-Tertiary Entomostraca of

Qcotland, &c., with an Introduction on the Post-
Tertiary Deposits of Scotland' (Ibid.) G. S. Brady,
H. W. Crosskey, and D. Robertson.

(15) "Reports on Kent's Cavern "--' British Association Re-

ports.' Pengelly.

(16) "Reports on the Victoria Cavern, Settle" — 'British

Association Reports.' Tiddeman.

(17) ' Ossemens Fossiles.' Cuvier.

3&> HISTORICAL PALEONTOLOGY.

(18) ' Reliquiae Diluvianae.' Buckland.

(19) "Fossil Mammalia "— ' Zoology of the Voyage of the

Beagle.' Owen.

(20) 'Description of the Tooth and Part of the Skeleton of

the Glyptodon' Owen.

(21) "Memoir on the Extinct Sloth Tribe of North

America " — ' Smithsonian Contributions to Knowl-
edge.' Leidy.

(22) "Report on Extinct Mammals of Australia "—'British

Association, ' 1844. Owen.

(23) 'Description of the Skeleton of an Extinct Gigantic

Sloth (Mylodon robustus).' Owen.

(24) "Affinities and Probable Habits of Thylacoleo "—

' Quart. Journ. Geol. Soc.,' vol. xxiv. Flower.

(25) ' Prodromus of the Palaeontology of Victoria.' M'Coy.

(26) 'Les Ossemens Fossiles des Cavernes de Liege.'

Schmerling.

(27) 'Die Fauna der Pfahlbauten in der Schweiz.' Riiti-

meyer.

(28) " Extinct and Existing Bovine Animals of Scandinavia "

— ' Annals of Natural History,' ser. 2, vol. iv., 1849.
Nilsson.

(29) ' Man's Place in Nature.' Huxley.

(30) 'Les Temps Antehistoriques en Belgique.' Dupont.

(31) "Classification of the Pleistocene Strata of Britain and

the Continent " — ' Quart. Journ. Geol. Soc.,' vol.
xxviii. Boyd Dawkins.

(32) 'Distribution of the Post-Glacial Mammalia' (Ibid.)

vol. xxv. Boyd Dawkins.

(33) ' On British Fossil Oxen' (Ibid.), vols. xxii. and xxiii.

Boyd Dawkins.

(34) 'British Prehistoric Mammals' (Congress of Pre-

historic Archaeology, 1868). Boyd Dawkins.

(35) 'Reliquiae Aquitanicae.' Lartet and Christy.

(36) ' Zoologie et Paleontologie Frangaises.' Gervais.

(37) ' Notes on the Post- Pliocene Geology of Canada.'

Dawson.

(38) " On the Connection between the existing Fauna and

Flora of Great Britain and certain Geological
Changes " — ' Mem. Geol. Survey.' Edward Forbes.

(39) ' Cavern-Researches.' M'Enery. Edited by Vivian.

(40) " Quaternary Gravels " — ' Quart. Journ. Geol. Soc./ vol.

xxv. Tylor.

SUCCESSION OF LIFE UPON THE GLOBE. 381

CHAPTER XXIII.

THE SUCCESSION OF LIFE UPON THE GLOBE.

In conclusion, it may not be out of place if we attempt to
summarize, in the briefest possible manner, some of the prin-
cipal results which may be deduced as to the succession of
life upon the earth from the facts which have in the preceding
portion of this work been passed in review. That there was
a time when the earth was void of life is universally admitted,
though it may be that the geological record gives us no direct
evidence of this. That the globe of to-day is peopled with
innumerable forms of life whose term of existence has been,
for the most part, but as it were of yesterday, is likewise an
assertion beyond dispute. Can we in any way connect the
present with the remote past, and can we indicate even im-
perfectly the conditions and laws under which the existing
order was brought about? The long series of fossiliferous
deposits, with their almost countless organic remains, is the
link between what has been and what is; and if any answer
to the above question can be arrived at, it will be by the
careful and conscientious study of the facts of Palaeontology.
In the present state of our knowledge, it may be safely said
that anything like a dogmatic or positive opinion as to the
precise sequence of living forms upon the globe, and still
more as to the manner in which this sequence may have been
brought about, is incapable of scientific proof. There are,
however, certain general deductions from the known facts
which may be regarded as certainly established.

In the first place, it is certain that there has been a succession
of life upon the earth, different specific and generic types suc-
ceeding one another in successive periods. It follows from
this, that the animals and plants with which we are familiar as
living, were not always upon the earth, but that they have been
preceded by numerous races more or less differing from them.
What is true of the species of animals and plants, is true also
of the higher zoological divisions; and it is, in the second

382 HISTORICAL PALAEONTOLOGY.

place, quite certain that there has been a similar succession in
the order of appearance of the primary groups (" sub-king-
doms," "classes," &c.) of animals and • vegetables. These
great groups did not all come into existence at once, but they
made their appearance successively. It is true that we can-
not be said to be certainly acquainted with the first absolute
appearance of any great group of animals. No one dare
assert positively that the apparent first appearance of Fishes
in the Upper Silurian is really their first introduction upon the
earth : indeed, there is a strong probability against any such
supposition. To whatever extent, however, future discoveries
may push back the first advent of any or all of the great
groups of life, there is no likelihood that anything will be found
out which will materially alter the relative succession of these
groups as at present known to us. It is not likely, for
example, that the future has in store for us any discovery by
which it would be shown that Fishes were in existence before
Molluscs, or that Mammals made their appearance before
Fishes. The sub-kingdoms of Invertebrate animals were all
represented in Cambrian times — and it might therefore be in-
ferred that these had all come simultaneously into existence ;
but it is clear that this inference, though incapable of actual
disproof, is in the last degree improbable. Anterior to the
Cambrian is the great series of the Laurentian, .which, owing
to the metamorphism to which it has been subjected, has so
far yielded but the singular Eozo'dn. We may be certain,
however, that others of the Invertebrate sub-kingdoms besides
the Protozoa were in existence in the Laurentian period ; and
we may infer from known analogies that they appeared suc-
cessively, and not simultaneously.

When we come to smaller divisions than the sub-king-
doms— such as classes, orders, and families — a similar suc-
cession of groups is observable. The different classes of
any given sub-kingdom, or the different orders of any given
class, do not make their appearance together and all at once,
but they are introduced upon the earth in succession. More
than this, the different classes of a sub-kingdom, or the differ-
ent orders of a class, in the main succeed one another in the
relative order of their zoological rank — the lower groups appear-
ing first and the higher groups last. It is true that in the
Cambrian formation — the earliest series of sediments in which
fossils are abundant — we find numerous groups, some very
low, others very high, in the zoological scale, which appear

SUCCESSION OF LIFE UPON THE GLOBE. 383

to have simultaneously flashed into existence. For reasons
stated above, however, we cannot accept this appearance as
real ; and we must believe that many of the Cambrian groups
of animals really came into being long before the commence-
ment of the Cambrian period. At any rate, in the long series
of fossiliferous deposits of later date than the Cambrian the
above-stated rule holds good as a broad generalization — that
the lower groups, namely, precede the higher in point of time ;
and though there are apparent exceptions to the rule, there
are none of such a nature as not to admit of explanation.
Some of the leading facts upon which this generalization is
founded will be enumerated immediately; but it will be well,
in the first place, to consider briefly what we precisely mean
when we speak of " higher " and " lower " groups.

It is well known that naturalists are in the habit of " clas-
sifying" the innumerable animals which now exist upon the
globe; or, in other words, of systematically arranging them into
groups. The precise arrangement adopted by one naturalist
may differ in minor details from that adopted by another; but
all are agreed as to the fundamental points of classification,
and all, therefore, agree in placing certain groups in a certain
sequence. What, then, is the principle upon which this
sequence is based ? Why, for example, are the Sponges placed
below the Corals; these below the Sea-Urchins ; and these, again,
below the Shell-fish? W'ithout entering into a discussion of
the principles of zoological classification, which would here be
out of place, it must be sufficient to say that the sequence in
question is based upon the relative type of organisation of the
groups of animals classified. The Corals are placed above the
Sponges upon the ground that, regarded as a whole, the plan
or type of structure of a Coral is more complex than that of a
Sponge. It is not in the slightest degree that the Sponge is in
any respect less highly organized or less perfect, as a Sponge,
than is the Coral as a Coral ? Each is equally perfect in its
own way; but the structural pattern of the Coral is the highest,
and therefore it occupies a higher place in the zoological scale.
It is upon this principal, then, that the primary subdivisions
of the animal kingdom (the so-called "sub-kingdoms") are
arranged in a certain order. Coming, again, to the minor
subdivisions (classes, orders, &c.) of each sub-kingdom, we
find a different but entirely analogous principal employed as a
means of classification. The numerous animals belonging to
any given sub-kingdom are formed upon the same fundamental

384 HISTORICAL PALAEONTOLOGY.

plan of structure ; but they nevertheless admit of being ar-
ranged in a regular series of groups. All the Shell-fish, for
example, are built upon a common plan, this plan representing
the ideal Mollusc; but there are at the same time various
groups of the Mollusca, and these groups admit of an arrange-
ment in a given sequence. The principle adopted in this case
is simply of the relative elaboration of the common type. The
Oyster is built upon the same ground-plan as the Cuttle-fish ; but
this plan is carried out with much greater elaboration, and with
many more complexities, in the latter than in the former: and
in accordance with this, the Cephalopoda consistitute a higher
group than the Bivalve Shell-fish. As in the case of superiority
of structural type, so in this case also, it is not in the least that
the Oyster is an imperfect animal. On the contrary, it is just
as perfectly adapted by its organization to fill its own sphere
and to meet the exigencies of its own, existence as is the
Cuttle-fish; but the latter lives a life which is, physiologically,
higher than the former, and its organization is correspondingly
increased in complexity.

This being understood, it may be repeated that, in the
main, the succession of life upon the globe in point of time
has corresponded with the relative order of succession of the
great groups of animals in zoological rank; and some of the
more striking examples of this may be here alluded to.
Amongst the Echinoderms, for instance, the two orders gen-
erally admitted to be the " lowest " in the zoological scale —
namely, the Crinoids and the Cystoids — are likewise the oldest,
both appearing in the Cambrian, the former slowly dying out
as we approach the Recent period, and the latter disappearing
wholly before the close of the Palaeozoic period. Amongst the
Crustaceans, the ancient groups of the Trilobites, Ostracodes,
Phyllopods, Eurypterids, and Limuloids, some of which exist
at the present day, are all " low " types ; whereas the highly-
organized Decapods do not make their appearance till the near the
close of the Palaeozoic epoch, and they do not become abun-
dant till we reach Mesozoic times. Amongst the Mollusca,
those Bivalves which possess breathing-tubes (the " siphonate "
Bivalves) are generally admitted to be higher than those which
are destitute of these organs (the " asiphonate " Bivalves) ; and
the latter are especially characteristic of the Palaeozoic period,
whilst the former abound in Mesozoic and Kainozoic forma-
tions. Similarly, the Univalves with breathing-tubes and a
corresponding notch in the mouth of the shell (" siphonosto-

SUCCESSION OF LIFE UPON THE GLOBE. 385

matous " Univalves) are regarded as higher in the scale than
the round-mouthed vegetable-eating Sea-snails, in which no
respiratory siphons exist (" holostomatous " Univalves) ; but
the latter abound in the Palaeozoic rocks — whereas the former
do not make their appearance till the Jurassic period, and
their higher groups do not seem to have existed till the close
of the Cretaceous. The Cephalopods, again — the highest of all
the groups of Mollusca — are represented in the Palaeozoic
rocks exclusively by Tetrabranchiate forms, which constitute
the lowest of the two orders of this class; whereas the more
highly specialized Dibranchiates do not make their appearance
till the commencement of the Mesozoic. The Palaeozoic
Tetrabranchiates, also are of a much simpler type than the
highly complex Ammonitidce of the Mesozoic.

Similar facts are observable amongst the Vertebrate animals.
The Fishes are the lowest class of Vertebrates, and they are
the first to appear, their first certain occurrence being in the
Upper Silurian ; whilst, even if the Lower Silurian and Upper
Cambrian " Conodonts " were shown to be the teeth of Fishes,
there would still remain the enormously long periods of the
Laurentian and Lower Cambrian, during which there were In-
vertebrates, but no Vertebrates. The Amphibians, the next
class in zoological order, appears later than the Fishes, and
is not represented till the Carboniferous ; whilst its highest
group (that of the Frogs and Toads) does not make its entrance
upon the scene till Tertiary times are reached. The class of
the Reptiles, again, the next in order, does not appear till
the Permian, and therefore not till after Amphibians of very
varied forms had been in existence for a protracted period.
The Birds seem to be undoubtedly later than the Reptiles;
but, owing to the uncertainty as to the exact point of their first
appearance, it cannot be positively asserted that they pre-
ceded Mammals, as they should have done. Finally, the
Mesozoic types of Mammals are mainly, if not exclusively,
referable to the Marsupials, one of the lowest orders of the
class ; whilst the higher orders of the " Placental " Quadrupeds
are not with certainty known to have existed prior to the com-
mencement of the Tertiary period.

Facts of a very similar nature are offered by the succession
of Plants upon the globe. Thus the vegetation of the Palaeo-
zoic period consisted principally of the lowly-organized groups
of the Cryptogamous or Flowerless plants. The Mesozoic
formations, up to the Chalk, are especially characterized by the
25

386 HISTORICAL PALEONTOLOGY.

naked-seeded Flowering plants — the Conifers and the Cycads;
whilst the higher groups of the Angiospermous Exogens and
Monocotyledons characterize the Upper Cretaceous and Ter-
tiary rocks.

Facts of the above nature — and they could be greatly multi-
plied— seem to point clearly to the existence of some law of
progression, though we certainly are not yet in a position to
formulate this law, or to indicate the precise manner in which
it has operated. Two considerations, also, must not be over-
looked. In the first place, there are various groups, some of
them highly organized, which make their appearance at an ex-
tremely ancient date, but which continue throughout geological
time almost unchanged, and certainly unprogressive. Many of
these " persistent types " are known — such as various of the
Foraminifera, the Lingulce, the Nautili, &c. ; and they indicate
that under given conditions, at present unknown to us, it is
possible for a life-form to subsist for an almost indefinite period
without any important modification of its structure. In the
second place, whilst the facts above mentioned point to some
general law of progression of the great zoological groups, it
cannot be asserted that the primeval types of any given group
are necessarily "lower," zoologically speaking, than their
modern representatives. Nor does this seem to be at all
necessary for the establishment of the law in question. It
cannot be asserted, for example, that the Ganoid and Placoid
Fishes of the Upper Silurian are in themselves less highly
organized than their existing representatives; nor can it even
be asserted that the Ganoid and Placoid orders are low groups
of the class Pisces. On the contrary, they are high groups;
but then it must be remembered that these are probably not
really the first Fishes, and that if we meet with Fishes at some
future time in the Lower Silurian or Cambrian, these may
easily prove to be representatives of the lower orders of the
class. This question cannot be further entered into here, as
its discussion could be carried out to an almost unlimited
length; but whilst there are facts pointing both ways, it
appears that at present we are not justified in asserting that the
earlier types of each group — so far as these are known to us,
or really are without predecessors — are necessarily or invariably
more " degraded " or " embryonic " in their structure than
their more modern representatives.

It remains to consider very briefly how far Palaeontology
supports the doctrine of " Evolution, " as it is called ; and this,

SUCCESSION OF LIFE UPON THE GLOBE. 387

too, is a question of almost infinite dimensions, which can but
be glanced at here. Does Palaeontology teach us that the
almost innumerable kinds of animals and plants which we
known to have successively flourished upon the earth in past
times were produced separately and wholly independently of
each other, at successive periods ? or does it point to the
theory that a large number of these supposed distinct forms
have been in reality produced by the slow modification of a
comparatively small number of primitive types ? Upon the
whole, it must be unhesitatingly replied that the evidence of
Palaeontology is in favor of the view that the succession of
life-forms upon the globe has been to a large extent regulated
by some orderly and constantly-acting law of modification and
evolution. Upon no other theory can we comprehend how
the fauna of any given formation is more closely related to
that of the formation next below in the series, and to that of
the formation next above, than to that of any other series of
deposits. Upon no other view can we comprehend why the
Post-Tertiary Mammals of South America should consist prin-
cipally of Edentates, Llamas, Tapirs, Peccaries, Platyrhine
Monkeys, and other forms now characterizing this continent;
whilst those of Australia should be wholly referable to the
order of Marsupials. On no other view can we explain the
common occurrence of " intermediate " or " transitional "
forms of life, filling in the gaps between groups now widely
distinct.

On the other hand, there are facts which point clearly to the
existence of some law other than that of evolution, and prob-
ably of a deeper and more far-reaching character. Upon no
theory of evolution can we find a satisfactory explanation for
the constant introduction throughout geological time of new
forms of life, which do not appear to have been preceded by
pre-existent allied types. The Graptolites and Trilobites have
no known predecessors, and leave no known successors. The
Insects appear suddenly in the Devonian, and the Arachnides
and Myriapods in the Carboniferous, under well-differentiated
and highly-specialized types. The Dibranchiate Cephalopods
appear with equal apparent suddenness in the older Mesozoic
deposits, and no known type of the Palaeozoic period can be
pointed to as a possible ancestor. The Hifipuritida of the
Cretaceous burst into a varied life to all appearance almost
immediately after their first introduction into existence. The
wonderful Dicotyledonous flora of the Upper Cretaceous

388 HISTORICAL PALAEONTOLOGY.

period similarly surprises us without any prophetic annuncia-
tion from the older Jurassic.

Many other instances could be given; but enough has been
said to show that there is a good deal to be said on both sides,
and that the problem is one environed with profound difficul-
ties. One point only seems now to be universally conceded,
and that is, that the record of life in past time is not interrupted
by gaps other than those due to the necessary imperfections of
the fossiliferous series, to the fact that many animals are in-
capable of preservation in a fossil condition, or to other causes
of a like nature. All those who are entitled to speak on this
head are agreed that the introduction of new and the destruc-
tion of old species have been slow and gradual processes, in no
sense of the term " catastrophistic." Most are also willing to
admit that " Evolution " has taken place in the past, to a
greater or less extent, and that a greater or less number of so-
called species of fossil animals are really the modified descend-
ants of pre-existent forms. How this process of evolution has
been effected, to what extent it has taken place, under what
conditions and laws it has been carried out, and how far it
may be regarded as merely auxiliary and supplemental to some
deeper law of change and progress, are questions to which, in
spite of the brilliant generalizations of Darwin, no satisfactory
answer can as yet be given. In the successful solution of this
problem — if soluble with the materials available to our hands
— will lie the greatest triumph that Palaeontology can hope to
attain ; and there is reason to think that, thanks to the guiding-
clue afforded by the genius of the author of the ' Origin of
Species/ we are at least on the road to a sure, though it may
be a far-distant, victory.

APPENDIX.

TABULAR VIEW OF THE CHIEF DIVISIONS
OF THE ANIMAL KINGDOM.

(Extinct groups are marked with an asterisk. Groups not rep-
resented at all as fossils are marked with two asterisks.)

INVERTEBRATE ANIMALS.

SUB-KINGDOM I. — PROTOZOA.

Animal simple or compound ; body composed of " sarcode, "
not definitely segmented ; no nervous system ; and no digestive
apparatus, beyond occasionally a mouth and gullet.

CLASS I. GREGARINID^:. **
CLASS II. RHIZOPODA.

Order i. Monera. **

Order 2. Ama?bea. **

Order 3. Foraminifera.

Order 4. Radiolaria ( Polycystines, &c.)

Order 5. Spongida (Sponges).
CLASS III. INFUSORIA. **

SUB-KINGDOM II. — CCELENTERATA.

Animal simple or compound; body-wall composed of two
principal layers; digestive canal freely communicating with the
general cavity o'f the body ; no circulating organs, and no
nervous system or a rudimentary one ; mouth surrounded by
tentacles, arranged, like the internal organs, in a " radiate " or
star-like manner.

(389)

390 APPENDIX.

CLASS I. HYDROZOA.

Sub-class i. Hydroida (" Hydroid Zoophytes"). Ex.

Freshwater Polypes,** Pipe - corallines (Tubularia),

Sea - Firs (Sertularia).
Sub-class 2. Siphonophora** (" Oceanic Hydrozoa").

Ex. Portuguese Man-of-war (Physalia).
Sub-class 3. Discophora ("Jelly-fishes"). Only known

as fossils by impressions of their stranded carcasses.
Sub-class 4. Luccrnarida (" Sea-blubbers "). Also only

known as fossils by impressions left in fine-grained

strata.
Sub-class 5. Graptolitidce* (" Graptolites ").

CLASS II. ACTINOZOA.

Order i. Zoantharia. Ex. Sea-anemones** (Actin-
idce), Star-corals (Astr&idtf).

Order 2, Alcyonaria. Ex. Sea-pens (Pennatula), Or-
gan-pipe Coral (Tubipora), Red Coral (Corallium).

Order 3. Rugosa ("Rugose Corals").

Order 4. Ctenophora.** Ex. Venus's Girdle (Cestum).

SUB-KINGDOM III. — ANNULOIDA.

Animals in which the digestive canal is completely shut off
from the cavity of the body ; a distinct nervous system ; a
system of branched " water-vessels, " which usually communi-
cate with the exterior. Body of the adult often " radiate, " and
never composed of a succession of definite rings.

CLASS I. ECHINODERMATA.

Order i. Crinoidea ("Sea-lilies"). Ex. Feather-star

(Comatula), Stone-lily (Encrinus*).
Order 2. Blastotdea* (" Pentremites ").
Order 3. Cystoidea* ("Globe-lilies").
Order 4. Ophiuroidea ("Brittle-stars"). Ex. Sand-stars

(Ophiura), Brittle-stars (Ophiocoma}.
Order 5. Asteroidea ("Star-fishes"). Ex. Cross-fish

(Uraster), Sun-star (Solaster}.
Order 6. Echinoidea ("Sea-urchins"). Ex. Sea-eggs

(Echinus), Heart-urchins (Spatangus).
Order 7. Holothuroidea (" Sea - cucumbers "). Ex. Tre-

pangs (Holothuria).

CLASS II. SCOLECIDA** (Intestinal Worms, Wheel Animalcules,
&c.)

SUB-KINGDOM IV. — ANNULOSA.

Animal composed of numerous definite segments placed one
behind the other; nervous system forming a knotted cord placed
along the lower (ventral) surface of the body.

APPENDIX. 391

Division A. Anarthropoda. No jointed limbs.

CLASS I.-GEPHYREA** ("Spoon-worms").

CLASS II. ANNELIDA ("Ringed-worms"). Ex. Leeches**
(Hirudinea), Earthworms** Oligochceta), Tube-worms
(Tubicola), Sea-worms and Sea-centipedes (Errantia).

CLASS III. CH^TOGNATHA ** ("Arrow-worms").

Division B. Arthropoda or Articulata. Limbs jointed to the
body.

CLASS I. CRUSTACEA ("Crustaceans"). Ex. Barnacles and
Acorn-shells (Cirripedia), Water-fleas (Ostracoda),
Brine-shrimps and Fairy-shrimps (Phyllopoda), Trilo-
bites * (Trilobita), King-crabs and Eurypterids * (Mer-
ostomata), Wood-lice and Slaters (Isopoda), Sand-hop-
pers (Amphipoda), Lobsters, Shrimps, Hermit-crabs, and
Crabs (Decapoda).

CLASS II. ARACHNIDA. Ex. Mites (Acarina), Scorpions (Pedi-
palpi), Spiders (Araneida).

CLASS III. MYRIAPODA. Ex. Centipedes (Chilopoda), Millipedes
and Galley-worms (Chilognatha).

CLASS IV. INSECTA ("Insects"). Ex. Field-bugs (Hemiptera) ;
Crickets, Grasshoppers, &c. (Orthoptera) ; Dragon-flies
and May-flies {Neuroptera} ; Gnats and House-flies (Dip-
tera] ; Butterflies and Moths (Lepidoptera} ; Bees, Wasps
and Ants (Hymenoptera) ; Beetles (Coleoptera).

SUB-KINGDOM V. — MOLLUSCA.

Animal soft-bodied, generally with a hard covering or shell ;
no distinct segmentation of the body ; nervous system of scat-
tered masses. •

CLASS I. POLYZOA ("Sea-Mosses"). Ex. Sea-mats (Flustra),

Lace-corals (Fenestellidte*}.
CLASS II. TUNICATA ** (" Tunicaries ") Ex. Sea-squirts

(Ascidia}.
CLASS III. BRACHIOPODA ("Lamp-shells"). Ex. Goose-bill

Lamp-shell (Lingula}.
CLASS IV. LAMELLIBRANCHIATA ("Bivalves"). Ex. Oyster

(Ostrea}, Mussel (Mytilus}, Scallop (Pecten), Cockle

(Cardium).
CLASS V. GASTEROPODA ("Univalves"). Ex. Whelks (Bucci-

num}, Limpets (Patella), Sea-slugs** (Doris), Land-
snails (Helix).
CLASS VI. PTEROPODA ("Winged Snails"). Ex Hyalea, Cleo-

dora.
CLASS VII. CEPHALOPODA ("Cuttle-fishes"). Ex. Calamary

(Loligo), Poulpe (Octopus), Paper Nautilus (Argon-

auta), Pearly Nautilus (Nautilus), Belemnites, * Ortho-

ceratites, * Ammonites. *

392 APPENDIX.

VERTEBRATE ANIMALS.

SUB-KINGDOM VI. — VERTEBRATA.

Body composed of definite segments arranged longitudinally
one behind the other ; main masses of the nervous system placed
dorsally; a backbone or "vertebral column" in the majority.

CLASS I. PISCES ("Fishes"). Ex. Lancelet * * (Amphioxus}'',
Lampreys and Hag-fishes (Marsipobranchii * *) ; Herring,
Salmon, Perch, &c. (Teleostei or "Bony Fishes"); Gar-
pike, Sturgeon, &c. (Ganoidei} ; Sharks, Dog-fishes, Rays,
&c. (Elasmobranchii or "Placoids").

CLASS II. AMPHIBIA ("Amphibians"). Ex. Labyrinthodontia,*
Csecilians, * * Newts and Salamanders (Urodela), Frogs
and Toads (Anoura}.

CLASS III. REPTILIA ("Reptiles"). Ex. Deinosauria,* Ptero-
sauria,* Anomodontia,* Plesiosaurs (Sauropterygia*),
Ichthyosaurs (Ichthyopterygia*), Tortoises and Turtles
(Chelonia}, Snakes (Ophidia), Lizards (Lacertilia),
Crocodiles (Crocodilia}.

CLASS IV. AVES ("Birds"). Ex. Toothed Birds (Odontor-
nithes*}; Lizard-tailed Birds (Archceopteryx *) ; Ducks,
Geese, Gulls, &c. (Natatores} ; Storks, Herons, Snipes,
Plovers, &c. (Grallatores) ; Ostrich, Emeu, Cassowary,
Dinornis, * ^piornis, * &c. (Cursorcs) ; Fowls, Game
Birds and Doves (Rasores} ; Cuckoos, Woodpeckers,
Parrots, &c. (Scansores) ; Crows, Starlings, Finches,
Humming-birds, Swallows, &c. (Insessores) ; Owls,
Hawks, Eagles, Vultures (Raptores}.

CLASS V. MAMMALIA ("Quadrupeds"). Ex. Duck-mole and
Spiny Ant-eater (Monotremata * *) ; Kangaroos, Phal-
• angers, Opossums, Tasmanian Devil, &c. (Marsupialia) ;
Sloths, Ant-eaters, Armadillos (Edentata} ; Manatees
and Dugongs (Sirenid) ; Whales, Dolphins, Porpoises
(Cetacea) ; Rhinoceros, Tapir, Horses, Hippopotamus,
Pigs, Camels and Llamas, Giraffes, Deer, Antelopes,
Sheep, Goats, Oxen (Ungulata} ; Hyrax (Hyracoidea * *) ;
Elephants, Mastodon, * Deinotherium * (Proboscidea} ;
Seals, Walrus, Bears, Dogs, Wolves, Cats, Lions, Tigers,
&c. (Carnivora} ; Hares, Rabbits, Porcupines, Beavers,
Rats, Mice, Lemmings Squirrels, Marmots, &c. (Rodeii-
tia} ; Bats (Cheiroptera} ; Moles, Shrew-mice, Hedge-
hogs (Insectivora} ; Lemurs, Spider-monkeys, Macaques,
Baboons, Apes (Quadrumana} ; Man (Bimana).

GLOSSARY

ABDOMEN (Lat. abdo, I conceal). The posterior cavity of the
body, containing the intestines and others of the viscera. In
many Invertebrates there is no separation of the body-cavity
into thorax and abdomen, and it is only in the higher Annulosa
that a distinct abdomen can be said to exist.

ABERRANT (Lat. aberro, I wander away). Departing from the
regular type.

ABNORMAL (Lat. ab, from; norma, a rule). Irregular; deviating
from the ordinary standard.

ACRODUS (Gr. akros, high; odous, tooth). A genus of the Ces-
traciont fishes; so-called from the elevated teeth.

ACROGENS (Gr. akros, high; gennao, I produce). Plants which
increase in height by additions made to the summit of the
stem by the union of the bases of the leaves.

ACROTRETA (Gr. akros, high; trStos, pierced). A genus of
Brachiopods, so-called from the presence of a foramen at
the summit of the shell.

ACTINOCRINUS (Gr! aktin, a ray; krinon, a lily). A genus of
Crinoids.

ACTINOZOA (Gr. aktin, a ray; and zo'on, an animal). That
division of the Ccelenterata of which the Sea-anemones may be
taken as the type.

yEGLiNA (jEgli, a sea-nymph). A genus of Trilobites.

^PIORNIS (Gr. aipus, huge; ornis, bird). A genus of gigantic
Cursorial birds.

AGNOSTUS (Gr. a, not; gignosko, I know). A genus of Trilo-
bites.

ALCES (Lat. dices, elk). The European Elk or Moose.

ALECTO (the proper name of one of the Furies). A genus of
Polyzoa.

ALETHOPTERIS (Gr. alZthZs, true; pteris, fern). A genus of
Ferns.

ALGJE (Lat. alga, a marine plant). The order of plants com-
prising the Sea-weeds and many fresh-water plants.

ALVEOLUS (Lat. alvus, belly). Applied to the sockets of the
teeth.

AMBLYPTERUS (Gr. amblus, blunt; pteron, fin). An order of
Ganoid Fishes.

(393)

394 GLOSSARY

AMBONYCHIA (Gr. ambon, a boss; onux, claw). A genus of
Palaeozoic Bivalves.

AMBULACRA (Lat. ambulacrum, a place for walking). The per-
forated spaces or " avenues " through which are protruded the
tube-feet, by means of which locomotion is effected in the
Echinodermata.

AMMONiTiDyE. A family of Tetrabranchiate Cephalopods, so-
called from the resemblance of the shell of the type-genus,
Ammonites, to the horns of the Egyptian God, Jupiter-Am-
mon.

AMORPHOZOA (Gr. a, without; morphe, shape; soon, animal). A
name sometimes used to designate the Sponges.

AMPHIBIA (Gr. amphl, both; bios, life). The Frogs, Newts,
and the like, which have gills when young, but can always
breathe air directly when adult.

AMPHICYON (Gr. am phi, both — implying doubt; kuDn, dog). An
extinct genus of Carnivora.

AMPHILESTES (Gr. amphl, both; lestZs, a thief). A genus of
Jurassic Mammals.

AMPHISPONGIA (Gr. amphi, both; spoggos, sponge). A genus
of Silurian sponges.

AMPHISTEGINA (Gr. dmphi, both; stege', roof). A genus of
Foraminifera.

AMPHITHERIUM (Gr. amphi, both; therion, beast). A genus of
Jurassic Mammals.

AMPHITRAGULUS (Gr. amphi, both; dim. of tragos, goat). An
extinct genus related to the living Musk-deer.

AMPLEXUS (Lat. an embrace). A genus of Rugose Corals.

AMPYX (Gr. ampux, a wreath or wheel). A genus of Trilo-
bites.

ANARTHROPODA (Gr. a, without; arthros, a joint; pous, foot).
That division of Annulose animals in which there are no
articulated appendages.

ANCHITHERIUM (Gr. agchi, near; therion, beast). An extinct
genus of Mammals.

ANCYLOCERAS (Gr. agkulos, crooked; ceras, horn). A genus of
Ammonitidce.

ANCYLOTHERIUM (Gr. agkulos, crooked; therion, beast). An
extinct genus of Edentate Mammals.

ANDRIAS (Gr. andrias, image of man). An extinct genus of
tailed Amphibians.

ANGIOSPERMS (Gr. angeion, a vessel; sperma, seed). Plants
which have their seeds enclosed in a seed-vessel.

ANNELIDA (a Gallicised form of Annulata}. The Ringed
Worms, which form one of the divisions of the Anarthropoda.

ANNULARIA (Lat. annulus, a ring). A genus of Palaeozoic
plants, with leaves in whorls.

ANNULOSA (Lat. annulus). The sub-kingdom comprising the
Anarthropoda and the Arthropoda or Articulata, in all of
which the body is more or less evidently composed of a suc-
cession of rings.

ANOMODONTIA (Gr. anomos, irregular; odous, tooth). An ex-
tinct order of Reptiles, often called Dicynodontia.

GLOSSARY 395

ANOMURA (Gr. anomos, irregular; oura, tail). A tribe of De-
capod Crustacea, of which the Hermit-crab is the type.

ANOPLOTHERID;E (Gr. anoplos, unarmed; ther, beast). A family
of Tertiary Ungulates.

ANOURA (Gr. a, without; oura, tail). The order of Amphibia
comprising the Frogs and Toads, in which the adult is desti-
tute of a tail. Often called Batrachia.

ANTENNA (Lat. antenna, a yard-arm). The jointed horns or
feelers possessed by the majority of the Articulata.

ANTENNULES (dim. of Antenna}. Applied to the smaller pair
of antennae in the Crustacea.

ANTHRACOSAURUS (Gr. anthrax, coal; saura, lizard). A genus
of Labyrinthodont Amphibians.

ANTHRAPAUEMON (Gr. anthrax, coal; palcemfin, a prawn — orig-
inally a proper name). A genus of long-tailed Crustaceans
from the Coal-measures.

ANTLERS. Properly the branches of the horns of the Deer tribe
(Cervidce}, but generally applied to the entire horns.

APIOCRINID^: (Gr. apion, a pear; krinon, lily). A family of
Crinoids — the " Pear-encrinites. "

APTERYX (Gr. a, without; pterux, a wing). A wingless bird
of New Zealand, belonging to the order Cursores.

AQUEOUS (Lat. aqua, water). Formed in or by water.

ARACHNIDA (Gr. arachne, a spider). A class of the Articulata,
comprising Spiders, Scorpions, and allied animals.

ARBORESCENT, Branched like a tree.

ARCH^EOCIDARIS (Gr. archaios, ancient; Lat. cidaris, a diadem).
A Palaeozoic genus of Sea-urchins, related to the existing
Cidaris.

ARCH.EO'CYATHUS (Gr. archaios, ancient; kuathos, cup). A
genus of Palaeozoic fossils allied to the Sponges.

ARCHyEOFTERYx (Gr. archaios, ancient; pterux, a wing). The
singular fossil bird which alone constitutes the order of the
Saurura.

ARCTOCYON (Gr. arctos, bear; kuon, dog). An extinct genus
of Carnivora.

ARENACEOUS. Sandy, or composed of grains of sand.

ARENICOLITES (Lat. arena, sand; colo, I inhabit). A genus
founded on burrows supposed to be formed by worms re-
sembling the living Lobworms (Arenicola).

ARTICULATA (Lat. articulus, a joint). A division of the animal
kingdom, comprising Insects, Centipedes, Spiders and Crus-
taceans, characterized by the possession of jointed bodies or
jointed limbs. The term Arthropoda is now more usually
employed.

ARTIODACTYLA (Gr. artios, even; daktulos, a finger or toe). A
division of the hoofed quadrupeds (Ungulata) in which each
foot has an even number of toes (two or four).

ASAPHUS (Gr. asaphZs, obscure). A genus of Trilobites.

ASCOCERAS (Gr. askos, a leather bottle; keras, horn). A genus
of Tetrabranchiate Cephalopods.

ASIPHONATE. Not possessing a respiratory tube or siphon. (Ap-
plied to a division of the Lamellibranchiate Molluscs.)

396 GLOSSARY

ASTEROID (Gr. aster, a star; and eidos, form). Star-shaped, or
possessing radiating lobes or rays like a star-fish.

ASTEROIDEA. An order of Echinodermata, comprising the Star-
fishes, characterized by their rayed form.

ASTEROPHYLLITES (Gr. aster, a star; phullon, leaf). A genus of
Palaeozoic plants, with leaves in whorls.

ASTRJEIVJE (Gr. Astros, a proper name). The family of the
Star-corals.

ASTYLOSPONGIA (Gr. a, without; stulos, a column; spoggos, a
sponge). A genus of Silurian Sponges.

ATHYRIS (Gr. a, without; thura, door). A genus of Brachiopods.

ATRYPA (Gr. a, without; trupa, a hole). A genus of Brachiopods.

AVES (Lat. avis, a bird). The class of the Birds.

AVICULA (Lat. a little bird). The genus of Bivalve Molluscs
comprising the Pearl-oysters.

AXOPHYLLUM (Gr. axon, a pivot; phullon, a leaf). A genus of
Rugose Corals.

Azoic (Gr. a, without; zoe, life). Destitute of traces of living
beings.

B

BACULITES (Lat. baculum, a staff). A genus of the Ammoni-
tid<z.

BAL^NA (Lat. a whale). The genus of the Whalebone Whales.

BALANID.E (Gr. balanos, an acorn). A family of sessile Cirri-
pedes, commonly called " Acorn-shells. "

BATRACHIA (Gr. batrachos, a frog). Often loosely applied to
any of the Amphibia, but sometimes restricted to the Am-
phibians as a class, or to the single order of the Anoura,

BELEMNITHLE (Gr. belemnon, a dart). An extinct group of
Dibranchiate Cephalopods, comprising the Belemnites and
their allies.

BELEMNOTEUTHIS (Gr. belemnon, a dart; teuthis, a cuttle-fish).
A genus allied to the Belemnites proper.

BELINURUS (Gr. belos, a dart; our a, tail). A genus of fossil
King-crabs.

BELLEROPHON (Gr. proper name). A genus of oceanic Uni-
valves (Heteropoda}.

BELOTEUTHIS (Gr. belos, a dart; teuthis, a cuttle-fish). An ex-
tinct genus of Dibranchiate Cephalopods.

BEYRICHIA (named after Prof. Beyrich). A genus of Ostra-
code Crustaceans.

BILATERAL. Having two symmetrical sides.

BIMANA (Lat. bis, twice; manus, a hand). The order of Mam-
malia comprising man alone.

BIPEDAL (Lat. bis, twice; pes, foot). Walking upon two legs.

BIVALVE (Lat. bis, twice valves, folding-doors). Composed of
two plates or valves; applied to the shell of the Lamellibran-
chiata and Brachiopoda, and to the carapace of certain Crus-
tacea.

BLASTOIDEA (Gr. blastos, a bud; and eidos, form). An extinct
order of Echinodermata, often called Pentremites.

GLOSSARY 397

BRACHIOPODA (Gr. brachion, an arm; pous, the foot). A class
of the Molluscoida, often called " Lamp-shells, " characterized
by possessing two fleshy arms continued from the sides of
the mouth.

BRACHYURA (Gr. brachus, short; oura, tail). A tribe of the
Decapod Crustaceans with short tails (/. e., the Crabs.)

BRADYPODID^E (Gr. bradus, slow; podes, feet). The family of
Edentata comprising the Sloths.

BRANCHIA (Gr. bragchia, the gill of a fish). A respiratory
organ adapted to breathe air dissolved in water.

BRANCHIATE. Possessing gills or branchiae.

BRONTEUS (Gr. bronte", thunder — an epithet of Jupiter the Thun-
derer). A genus of Trilobites.

BRONTOTHERIUM (Gr. brontf, thunder; therion, beast). An ex-
tinct genus of Ungulate Quadrupeds.

BRONTOZOUM (Gr. bronte*, thunder; soon, animal). A genus
founded on the largest footprints of the Triassic Sandstones
of Connecticut.

BUCCTNUM (Lat. buccinum, a trumpet). The genus of Uni-
valves comprising the Whelks.

CAINOZOIC (See Kainozoic.)

CALAMITES (Lat. calamus, a reed). Extinct plants with reed-
like stems, believed to be gigantic representatives of the

Equisetacece.

CALCAREOUS (Lat calx, lime). Composed of carbonate of lime.
CALICE. The little cup in which the polype of a coralligenous

Zoophyte (Act'mozo'dn) is contained.

CALYMENE (Gr. kalumene', concealed). A genus of Trilobites.
CALYX (Lat. a cup). Applied to the cup-shaped body of a

Crinoid (Echinodermata}.
CAMAROPHORIA (Gr. kamara, a chamber; phero, I carry). A

genus of Brachiopods.
CAMELOPARDALID^: (Lat. camelus, a camel; pardalis, a panther).

The family of the Giraffes.
CANINE (Lat. canis, a dog). The eye-tooth of Mammals, or

the tooth which is placed at or close to the praemaxillary suture

in the upper jaw, and the corresponding tooth in the lower

jaw.
CARAPACE. A protective shield. Applied to the upper shell of

Crabs, Lobsters, and many other Crustacea. Also the upper

half of the immovable case in which the body of a Chelonian

is protected.
CARCHARODON (Gr. karcharos, rough; odous, tooth). A genus

of Sharks.
CARDIOCARPON (Gr. kardia, the heart; karfios, fruit). A genus

of fossil fruit from the Coal-measures.
CARDIUM (Gr. kardia, the heart). The genus of Bivalve

Molluscs comprising the Cockles. Cardinia, Cardiola, and

Cardita have the same derivation.
CARNIVORA (Lat. caro, flesh; voro, I devour). An order of the

Mammalia. The " Beasts of Prey. "

398 GLOSSARY.

CARNIVOROUS (Lat. caro, flesh; voro, I devour). Feeding upon
flesh.

CARYOCARIS (Gr. karua, a nut; karis, a shrimp). A genus of
Phyllopod Crustaceans.

CARYOCRINUS (Gr. karua, a nut; krinon, a lily). A genus of
Cystideans.

CAUDAL (Lat. cauda, the tail). Belonging to the tail.

CAVICORNIA (Lat. cavus, hollow; cornu, a horn). The "hollow-
horned " Ruminants, in which the horn consists of a central
bony " horn-core " surrounded by a horny sheath.

CENTRUM (Gr. kentron, the point round which a circle is
described by a pair of compasses). The central portion or
" body " of a vertebra.

CEPHALASPIDVE (Gr. kephale, head; aspis, shield). A family of
fossil fishes.

CEPHALIC (Gr. kephale, head). Belonging to the head.

CEPHALOPODA (Gr. kephale; and podes, feet). A class of the
Mollusca, comprising the Cuttle-fishes and their allies, in
which there is a series of arms ranged round the head.

CERATIOCARIS (Gr. keras, a horn; karis, a shrimp). A genus pf
Phyllopod Crustaceans.

CERATITES (Gr. keras, a horn). A genus of Ammonitidce.

CERATODUS (Gr. keras, a horn; odous, tooth). A genus of
Dipnoous fishes.

CERVICAL (Lat. cervix, the neck). Connected with or belong-
ing to the region of the neck.

CERVID^E (Lat. cervus, a stag). The family of the deer.

CESTRAPHORI (Gr. kestra, a weapon; phero, I carry). The group
of the " Cestraciont Fishes, " represented at the present day
by the Port-Jackson Shark ; so-called from their defensive
spines.

CETACEA (Gr. ketos, a whale). The order of Mammals com-
prising the Whales and the Dolphins.

CETIOSAURUS (Gr. ketos, whale; saura, lizard). A genus of
Deinosaurian Reptiles.

CHEIROPTERA (Gr. cheir, hand; pteron, wing). The Mammalian
order of the Bats.

CHEIROTHERIUM (Gr. cheir, hand; thSrion, beast). The generic
name applied originally to the hand-shaped footprints of
Labyrinthodonts.

CHEIRURUS (Gr. cheir, hand; oura, tail). A genus of Trilo-
bites.

CHELONIA (Gr. chelone', a tortoise). The Reptilian order of
the Tortoises and Turtles.

CHONETES (Gr. chdne" or chDane', a chamber or box). A genus
of Brachiopods.

CIDARIS (Lat. a diadem). A genus of Sea-urchins.

CLADODUS (Gr. klados, branch; odous, tooth). A genus of
Fishes.

CLATHROPORA (Lat. clathri, a trellis; porus, a pore). A genus
of Lace-corals (Poly zoo).

CLISIOPHYLLUM (Gr. klision, a hut; phullon, leaf). A genus
of Rugose Corals.

GLOSSARY. 399

CLYMENIA (Clumene, a proper name). A genus of Tetra-
branchiate Cephalopods.

COCCOSTEUS (Gr. kokkos, berry; osteon, bone). A genus of
Ganoid Fishes.

COCHLIODUS (Gr. kochlion, a snail-shell; odous, tooth). A genus
of Cestraciont Fishes.

COELENTERATA (Gr. koilos, hollow ; enteron, the bowel). The
sub-kingdom which comprises the Hydrosoa and Actinozoa,
Proposed by Frey and Leuckhart in place of the old term
Radiata, which included other animals as well.

COLEOPTERA ( Gr. koleos, a sheath; pteron, wing). The order
of Insects (Beetles) in which the anterior pair of wings are
hardened, and serve as protective cases for the posterior pair
of membranous wings.

COLOSSOCHELYS (Gr. kolossos, a gigantic statue; chelus, a tor-
toise). A huge extinct Land-tortoise.

COMATULA (Gr. koma, the hair). The Feather-star, so-called
in allusion to its tress-like arms.

CONDYLE (Gr. kondulos, a knuckle). The surface by which one
bone articulates with another. Applied especially to the
articular surface or surfaces by which the skull articulates
with the vertebral column.

CONIFERS (Lat. conus, a cone; jero, I carry). The order of
the Firs, Pines and their allies, in which the fruit is generally
a " cone " or " fir-apple. "

CONULARIA (Lat. conulus, a little cone). An extinct genus of
Pteropods.

COPROLITES (Gr. kopros, dung; lithos, stone). Properly applied
to the fossilized excrements of animals ; but often employed
to designate phosphatic concretions which are not of this
nature.

CORALLITE. The corallum secreted by an Actinozo'dn which con-
sists of a single polype ; or the portion of a composite coral-
lum which belongs to, and is secreted by, an individual polype.

CORALLUM (from the Latin for' Red Coral). The hard structures
deposited in, or by, the tissues of an Actinozo'on — commonly
called a " coral. "

CORIACEOUS (Lat. corium, hide). Leathery.

CORYPHODON (Gr. korus, helmet; odous, tooth). An extinct
genus of Mammals, allied to the Tanirs.

CRANIUM (Gr. kranion, the skull). The bony or cartilaginous
case in which the brain is contained.

CRETACEOUS (Lat. creta, chalk). The formation which in
Europe contains white chalk as one of its most conspicuous
members.

CRINOIDEA (Gr. krinon, a lily; eidos, form). An order of
Echinodermata, comprising forms which are usually stalked,
and sometimes resemble lilies in shape.

CRIOCERAS (Gr. krios, a ram; keras, a horn). A genus of Am-
monitidc?.

CROCODILIA (Gr. krokodeilos, a crocodile). An order of Reptiles.

CROSSOPTERYGID^: (Gr. krossotos, a fringe; pterux, a fin). A
sub-order of Ganoids in which the paired fins possess a
central lobe.

400 GLOSSARY.

CRUSTACEA (Lat. crusta, a crust). A class of Articulate animals,

comprising Crabs, Lobsters, etc., characterized by trie pos-
session of a hard shell or crust, which they cast periodically.
CRYPTOGAMS (Gr. kruptos, concealed; games, marriage). A

division of plants in which the organs of reproduction are

obscure and there are no true flowers.
CTENACANTHUS (Gr. kteis, a comb; akantha, a thorn). A genus

of fossil fishes, named from its fin-spines.
CTENOID (Gr. kteis, a comb; eidos, form). Applied to those

scales of fishes the hinder margins of which are fringed with

spines or comb-like projections.
CURSORES (Lat. curro, I run). An order of Aves, comprising

birds destitute of the power of flight, but formed for running

vigorously (e. g., the Ostrich and Emeu).

CUSPIDATE. Furnished with small pointed eminences or " cusps. "
CYATHOCRINUS (Gr. kuathos, a cup; krinon, a lily). A genus

of Crinoids.
CYATHOPHYLLUM (Gr. kuathos, a cup; phullon, a leaf). A genus

of Rugose Corals.
CYCLOID (Gr. kuklos, a circle; eidos, form). Applied to those

scales of fishes which have a regularly circular or elliptical

outline with an even margin.
CYCLOPHTHALMUS (Gr. kuklos, a circle; opthalmos, eye). A

genus of fossil Scorpions.
CYCLOSTOMI (Gr. kuklos, and stoma, mouth). Sometimes used

to designate the Hag-fishes and Lampreys, forming the order

Marsipobranchii.
CYPR^A (a name of Venus). The genus of Univalve Molluscs

comprising the Cowries.
CYRTOCERAS (Gr. kurtos, crooked; keras, horn). A genus of

Tetrabranchiate Cephalopods.
CYSTIPHYLLUM (Gr. kustis, a bladder; phullon, a leaf). A genus

of Rugose Corals.
CYSTOIDEA (Gr. kustis, a bladder; eidos, form). The " Globe-

crinoids, " an extinct order of Echinodermata.

D

DADOXYLON (Gr. dadion, a torch; xulon, wood). An extinct
genus of Coniferous trees.

DECAPODA (Gr. deka, ten; podes, feet). The division of
Crustacea which have ten feet; also the family of Cuttle-
fishes, in which there are ten arms or cephalic processes.

DECIDUOUS (Lat. decido, I fall off). Applied to parts which
fall off or are shed during the life of the animal.

DEINOSAURIA (Gr. deinos, terrible; saura, lizard). An extinct
order of Reptiles.

DEINOTHERIUM (Gr. deinos, terrible; therion, beast). An extinct
genus of Proboscidean Mammals.

DENDROGRAPTUS (Gr. dendron, tree; grapho, I write). A genus
of Graptolites.

DESMIDUE. Minute fresh-water plants, of a green color, with-
out a siliceous epidermis.

GLOSSARY. 401

DIATOMACE^ (Gr. diatemno, I sever). An order of minute

plants which are provided with siliceous envelopes.
DIBRANCHIATA (Gr. dis, twice ; bragchia, gill). The order of

Cephalopoda (comprising the Cuttle-fishes, etc.,) in which only

two gills are present.
DICERAS (Gr. dis, twice; keras, horn). An extinct genus of

Bivalve Molluscs.
DICTYONEMA (Gr. diktuon, a net; nema, thread). An extinct

genus of Polyzoa (?).
DICYNODONTIA (Gr. dis, twice; kuon, dog; odous, tooth). An

extinct order of Reptiles.
DIDYMOGRAPTUS (Gr. didumos, twin; grapho, I write). A genus

of Graptolites.
DIMORPHODON (Gr. dis, twice; morphe, shape; odous, tooth). A

genus of Pterosaurian Reptiles.
DINICHTHYS (Gr. deinos, terrible; ichthus, fish). An extinct

genus of Fishes.
DINOCERAS (Gr. deinos, terrible; keras, horn). An extinct genus

of Mammals.
DINOPHIS (Gr. deinos, terrible; ophis, snake). An extinct genus

of Snakes.
DINORNIS (Gr. deinos, terrible; ornis, bird). An extinct genus

of Birds.
DIPLOGRAPTUS (Gr. diplos, double; grapho, I write). A genus

of Graptolites.

DIPNOI (Gr. dis, twice; pnoe', breath). An order of Fishes, com-
prising the Mud-fishes, so-called in allusion to their double

mode of respiration.
DIPROTODON (Gr. dis, twice; protos, first; odous, tooth). A genus

of extinct Marsupials.
DIPTERA (Gr. dis, twice; pterpn, wing). An order of Insects

characterized by the possession of two wings.
DISCOID (Gr. diskos, a quoit; eidos, form). Shaped like a round

plate or quoit.

DOLOMITE (named after M. Dolomieu). Magnesian limestone.
DORSAL (Lat. dor sum, the back). Connected with or placed upon

the back.
DROMATHERIUM (Gr. dromaios, nimble; thZrion, beast). A genus

of Triassic Mammals.
DRYOPITHECUS (Gr. drus, an oak; pithekos, an ape). An extinct

genus of Monkeys.

ECHINODERMATA (Gr. echinos ; and derma, skin). A class of
animals comprising the Sea-urchins, Star-fishes and others,
most of which have spiny skins.

ECHINOIDEA (Gr. echinos; and eidos, form). An order of
Echinodermata, comprising the Sea-urchins.

EDENTATA (Lat. e, without; dens, tooth). An order of Mam-
malia often called Bruta.

EDENTULOUS. Toothless, without any dental apparatus. Applied
to the mouth of any animal, or to the hinge of the Bivalve
Molluscs.
26

402 GLOSSARY.

ELASMOBRANCHII (Gr. elasma,.a plate; bragchia, gill). An order

of Fishes, including the Sharks and Rays.
ENALIOSAURIA (Gr. enalios, marine; saura, lizard). Sometimes

employed as a common term to designate the extinct Reptilian

orders of the Ichthyosauria and Plesiosauria.
EOCENE (Gr. eos, dawn; kainos, new or recent). The lowest

division of the Tertiary rocks, in which species of existing

shells are to a small extent represented.

EOPHYTON (Gr. eos, dawn; phuton, a plant). A genus of Cam-
brian fossils, supposed to be of a vegetable nature.
Eozo'dN (Gr. eos, dawn; zoon, animal). A genus of chambered

calcareous organisms found in the Laurentian and Huronian

formations.
EQUILATERAL (Lat. cequus, equal; latus, side). Having its sides

equal. Usually applied to the shells of the Brachiopoda.

When applied to the spiral shells of the Foraminifera, it

means that all the convolutions of the shell lie in the same

plane.
EQUISETACE^E (Lat. equus, horse; seta, bristle). A group of

Cryptogamous plants, commonly known as " Horse-tails. "
EQUIVALVE (Lat. (equus, equal; valvce, folding-doors). Applied

to shells which are composed of two equal pieces or valves.
ERRANTIA (Lat. erro, I wander). An order of Annelida, often

called Nereidea, distinguished' by their great locomotive

powers.
EUOMPHALUS (Gr. eu, well; omphalos, navel). An extinct genus

of Univalve Molluscs.

EURYPTERIDA (Gr. eurus, broad ; pteron, wing). An extinct sub-
order of Crustacea.
EXOGYRA (Gr. exo, outside; guros, circle). An extinct genus

of Oysters.

FAUNA (Lat. Fauni, the rural deities of the Romans). The
general assemblage of the animals of any region or district.

FAVOSITES (Lat. favos, a honeycomb). A genus of Tabulate
Corals.

FENESTELLID^: (Lat. fenestella, a little window). The "Lace-
corals, " a group of Palaeozoic Polyzoans.

FILICES (Lat. filix, a fern). The order of Cryptogamic plants
comprising the Ferns.

FILIFORM (Lat. filum, a thread; forma, shape). Thread-shaped.

FLORA (Lat. Flora, the goddess of flowers). The general
assemblage of the plants of any region or district.

FORAMINIFERA (Lat. foramen, an aperture; fero, I carry). An
order of Protozoa, usually characterized by the possession of
a shell perforated by numerous pseudopodial apertures.

FRUGIVOROUS (Lat. frux, fruit; voro, I devour). Living upon
fruits.

FUCOIDS (Lat. fucus, sea-weed; Gr. eidos, likeness). Fossils
often of an obscure nature, believed to be the remains of
sea-weeds.

FUSULINA (Lat. fusus, a spindle). An extinct genus of Fora-
minifera.

GLOSSARY. 403

GANOID (Gr. ganos, splendour, brightness). Applied to those
scales or plates which are composed of an inferior layer of
true bone covered by a superior layer of polished enamel.

GANOIDEI. An order of Fishes.

GASTEROPODA (Gr. gaster, stomach; pous, foot). The class of
the Mollusca comprising the ordinary Univalves, in which
locomotion is usually effected by a muscular expansion of
the under surface of the body (the "foot").

GLOBIGERINA (Lat. globus, a globe; gero, I carry). A genus of
Foraminifera.

GLYPTODON (Gr. glupho, I engrave; odous, tooth). An extinct
genus of Armadillos, so-named in allusion to the fluted teeth.

GONIATITES (Gr. gonia, angle). A genus of Tetrabanchiate
Cephalopods.

GRALLATORES (Lat. gralla, stilts). The order of the long-legged
Wading Birds.

GRAPTOLITID^: (Gr. grapho., I write; lithos, stone). An extinct
sub-class of the Hydrosoa.

GYMNOSPERMS (Gr. gumncs, naked; sperma, seed). The Conifers
and Cycads, in which the seed is not protected within a seed-
vessel.

H

HALITHERIUM (Gr. hals, sea; thtrion, beast). An extinct genus

of Sea-cows (Sirenia}.

HAMITES (Lat. hamus, a hook). A genus of the Ammonitidce.
HELIOPHYLLUM (Gr. helios, the sun; phullon, leaf). A genus

of Rugose Corals.
HELLADOTHERIUM (Gr. HZllas, Greece; thVrion, beast). An

extinct genus of Ungulate Mammals.
HEMIPTERA (Gr. hemi; and pteron, wing). An order of Insects

in which the anterior wings are sometimes " hemelytra. "
HESPERORNIS (Gr. Hesperos, the evening star; ornis, bird). An

extinct genus of Birds.
HETEROCERCAL (Gr. heteros, diverse; kerkos, tail). Applied to

the tail of Fishes when it is unsymmetrical, or composed of

two unequal lobes.
HETF.ROPODA (Gr. heteros, diverse; podes, feet). An aberrant

group of the Gasteropods, in which the foot is modified so as

to form a swimming organ.
HIPPARION (Gr. hipparion, a little horse). An extinct genus of

E quid a.
HIPPOPOTAMUS (Gr. hippos, horse; potamos, river). A genus of

hoofed Quadrupeds — the " River-horses. "
HIPPURITID^: (Gr. hippos, horse; oura, tail). An extinct family

of Bivalve Molluscs.
HOLOPTYCHIUS (Gr. holos, whole; ptuche*, wrinkle). An extinct

genus of Ganoid Fishes.
HOLOSTOMATA (Gr. holos, whole; stoma, mouth). A division of

Gasteropodous Molluscs, in which the aperture of the shell

is rounded, or " entire. "

404 GLOSSARY.

HOLOTHUROIDEA (Gr. holothourion, a kind of zoophyte ; and eidos,

form). An order of Echinodermata comprising the Trepangs.
HOMOCERCAL (Gr. homos, same; kerkos, tail). Applied to the

tail of Fishes when it is symmetrical, or composed of two

equal lobes.
HYBODONTS (Gr. hubos, curved; odous, tooth). A group of

Fishes of which Hybodus is the type-genus.
HYDROIDA (Gr. hudra, water-serpent; and eidos, form). The

sub-class of the Hydrozoa, which comprises the animals most

nearly allied to the Hydra.
HYDROZOA (Gr. hudra; and zoVn, animal). The class of the

Ccclenterata which cqmprises animals constructed after the

type of the Hydra.
HYMENOPTERA (Gr. humen, a membrane; pteron, a wing). An

order of Insects (comprising Bees, Ants, etc.) characterized

by the possession of four membranous wings.

ICHTHYODORULITE (Gr. ichthus, fish; dorus, spear; lithos, stone).
The fossil fin-spine of Fishes.

ICHTHYOPTERYGIA (Gr. ichthus \ pterux, wing). An extinct order
of Reptiles.

ICHTHYORNIS (Gr. ichthus, fish; ornis, bird). An extinct genus
of Birds.

ICHTHYOSAURIA (Gr. ichthus ; saura, lizard). Synonymous with
Ichthyopterygia.

IGUANODON {Iguana, a living lizard; Gr. odous, tooth). A genus
of Deinosaurian Reptiles.

INCISOR (Lat. incido, I cut). The cutting teeth fixed in the inter-
maxillary bones of the Mammalia, and the corresponding teeth
in the lower jaw.

INEQUILATERAL. Having the two sides unequal, as in the case
of the shells of the ordinary bivalves (Lamellibranchiata).
When applied to the shells of the Foraminifera, it implies that
the convolutions of the shell do not lie in the same plane,
but are obliquely wound round an axis.

INEQUIVALVE. Composed of two unequal pieces or valves.

INOCERAMUS (Gr. is, a fibre; keramos, an earthen vessel). An
extinct genus of Bivalve Molluscs.

INSECTA (Lat. inseco, I cut into). The class of articulate
animals commonly known as Insects.

INSECTIVORA (Lat. insectum, an insect; voro, I devour). An
order of Mammals.

INSECTIVOROUS. Living upon Insects.

INSESSORES (Lat. insedeo, I sit upon). The order of the Perch-
ing Birds, often called Passeres.

INTERAMBULACRA. The rows of plates in an Echinoid which are
not perforated for the emission of the " tube-feet. "

INTERMAXILL^E or PR^:MAXILL/E. The two bones which are
situated between the two superior maxillae in Vertebrata. In
man, and some monkeys, the praemaxillae anchylose with the
maxillae, so as to be irrecognizable in the adult.

GLOSSARY. 405

INVERTEBRATA (Lat. in, without; vertebra, a bone of the back).
Animals without a spinal column or backbone.

ISOPODA (Gr. isos, equal; podes, feet). An order of Crusta-
cea in which the feet are like one another and equal.

K

KAINOZOIC (Gr. kainos, recent; zoe, life). The Tertiary period
in Geology comprising those formations in which the organic
remains approximate more or less closely to the existing fauna
and flora.

LABYRINTHODONTIA (Gr. laburinthos, a labyrinth; odous, tooth).
An extinct order of Amphibia, so-called from the complex
microscopic structure of the teeth.

LACERTILIA (Lat. lacerta, a lizard). An order of Reptilia com-
prising the Lizards and Slow-worms.

LAMELLIBRANCHIATA (Lat. lamella, a plate; Gr. bragchia, gill).
The class of Mollusca comprising the ordinary bivalves, char-
acterized by the possession of lamellar gills.

LEPIDODENDRON (Gr. lepis, a scale; dendron, a tree). A genus of
extinct plants, so-named from the scale-like scars upon the
stem left by the falling off of the leaves.

LEPIDOPTERA (Gr. lepis, a scale; pteron, a wing). An order of
Insects, comprising Butterflies and Moths, characterized by
possessing four wings which are usually covered with minute
scales.

LEPIDOSIREN (Gr. lepis, a scale; seiren, a siren — the generic name
of the Mud-eel or Siren lacertina). A genus of Dipnoous
fishes, comprising the " Mud-fishes. "

LEPIDOSTROBUS (Gr. lepis. a scale; strobilos, a fir-cone). A genus
founded on the cones of Lepidodendron.

LEPT^NA (Gr. leptos, slender). A genus of Brachiopods.

LINGULA (Lat. lingula, a little tongue). A genus of Brachio-
pods.

LYCOPODIACE^: (Gr. lupos, a wolf; pous, foot). The group of
Cryptogamic plants generally known as " Club-mosses. "

M

MACH^RACANTHUS (Gr. machaira, a sabre ; acantha, thorn or
spine). An extinct genus of Fishes.

MACHAIRODUS (Gr. machaira, a sabre; odous, tooth). An ex-
tinct genus of Carnivora.

MACROTHERIUM (Gr. makros, long; therion, beast). An extinct
genus of Edentata.

MACRURA (Gr. makros, long; oura, tail). A tribe of Decapod
Crustaceans with long tails (e. g., the Lobster, Shrimp, etc.)

MAMMALIA (Lat. mamma, the breast). The class of Verte-
brate animals which suckle their young.

4o6 GLOSSARY.

MANDIBLE (Lat. mandibulum, a jaw). The upper pair of jaws
in Insects; also applied to one of the pairs of jaws in Crus-
tacea and Spiders, to the beak of Cephalopods, the lower jaw
of Vertebrates, etc.

MANTLE. The external integument of most of the Mollusca,
which is largely developed, and forms a cloak in which the
viscera are protected. Technically called the " pallium. "

MANUS (Lat. the hand). The hand of the higher Vertebrates.

MARSIPOBRANCHII (Gr. marsipos, a pouch; bragchia, gill). The
order of Fishes comprising the Hag-fishes and Lampreys, with
pouch-like gills.

MARSUPIALIA (Lat. marsupium, a pouch). An order of Mam-
mals in which the females mostly have an abdominal pouch
in which the young are carried.

MASTODON (Gr. mastos, nipple; odous, tooth). An extinct genus
of Elephantine Mammals.

MEGALONYX (Gr. megas, great; onux, nail). An extinct genus
of Edentate Mammals.

MEGALOSAURUS (Gr. megas, great; saura, lizard). A genus of
Deinosaurian Reptiles.

MEGATHERIUM (Gr. megas, great; thZrion, beast). An extinct
genus of Edentata.

MESOZOIC (Gr. mesos, middle; and zoe, life). The Secondary
period in Geology.

MICROLESTES (Gr. mikros, little; lestes, thief). An extinct genus
of Triassic Mammals.

MILLEPORA (Lat. mille, one thousand; porus, a pore). A genus
of '"Tabulate Corals."

MIOCENE (Gr. melon, less; kainos, new). The Middle Tertiary
period.

MOLARS (Lat. mola, a mill). The "grinders" in man, or the
teeth in diphyodont Mammals which are not preceded by
milk-teeth.

MOLLUSCA (Lat. mollis, soft). The sub-kingdom which includes
the Shell-fish proper, the Polysoa, the Tunicata, and the Lamp-
shells ; so-called from the generally soft nature of their
bodies.

MOLLUSCOIDA (Mollusca; Gr. eidos, form). The lower division
of the Mollusca, comprising the Polysoa, Tunicata, and Brach-
iopoda. .

MONOGRAPTUS (Gr. monos, single; grapho, I write). A genus
of Graptolites.

MYLODON (Gr. mulos, a mill; odous, tooth). An extinct genus
of Edentate Mammals.

MYRIAPODA or MYRIOPODA (Gr. murios, ten thousand; podes,
feet). A class of Arthropoda comprising the Centipedes and
their allies, characterized by their numerous feet.

N

NATATORES (Lat. nare, to swim). The order of the Swim-
ming Birds.

NATATORY (Lat. nare, to swim). Formed for swimming.
NAUTILOID. Resembling the shell of the Nautilus in shape.

GLOSSARY. 40?

NERVURES (Lat. nervus, a sinew). The ribs which support the

membranous wings of insects.
NEUROPTERA (Gr. neuron, a nerve; pier on, a wing). An order

of Insects characterized by four membranous . wings with

numerous reticulated nervures (e. g., Dragon-flies).
NEUROPTERIS (Gr. neuron, a nerve; pteris, a fern). An extinct

genus of Ferns.
NOTHOSAURUS (Gr. nothos, spurious; saura, lizard). A genus

of Plesiosaurian Reptiles.
NOTOCHORD (Gr. notos, back; chorde, string). A cellular rod

which is developed in the embryo of Vertebrates immediately

beneath the spinal cord, and which is usually replaced in the

adult by the vertebral column. Often it is spoken of as the

" chorda dorsalis. "
NUDIBRANCHIATA (Lat. nudus, naked; and Gr. bragchia, gill).

An order of the Gasteropoda in which the gills are naked.
NUMMULINA (Lat. nummus, a coin). A genus of Foramini-

fera, comprising the coin-shaped " Nummulites. "

O

OBOLELLA (Lat. dim of obolus, a small coin). An extinct genus

of Brachiopods.

OCCIPITAL. Connected with the occiput, or the back part of the
head.

OCEANIC. Applied to animals which inhabit the open ocean
(=pelagic).

ODONTOPTERYX (Gr. odous, tooth; pterux, wing). An extinct
genus of Birds.

ODONTORNITHES (Gr. odous, tooth; ornis, bird). The extinct
order of Birds, comprising forms with distinct teeth in sockets.

OLIGOCENE (Gr. oligos, few; kainos, new). A name used by
many Continental geologists as synonymous with the Lower
Miocene.

OPHIDIA (Gr. ophis, a serpent). The order of Reptiles com-
prising the Snakes.

OPHIUROIDEA (Gr. ophis, snake; oura, tail; eldos, form). An
order of Echinodermata, comprising the Brittle-stars and Sand-
stars.

ORNITHOSCELIDA (Gr. ornis, bird; skelo, leg). Applied by
Huxley to the Deinosaurian Reptiles, together with the genus
Compsognathus, on account of the bird-like character of their
hind-limbs.

ORTHIS (Gr. orthos, straight). A genus of Brachiopods, named
in allusion to the straight hinge-line.

ORTHOCERATID^: (Gr. orthos, straight; keras, horn). A family of
the Nautilidcz, in which the shell is straight, or nearly so.

ORTHOPTERA (Gr. orthos, straight; pteron, wing). An order of
Insects.

OSTEOLEPIS (Gr. osteon, bone; lepis, scale). An extinct genus
of Ganoid Fishes.

OSTRACODA (Gr. ostrakon, a shell). An order of small Crus-
taceans which are enclosed in bivalve shells.

4o8 GLOSSARY.

OTODUS (Gr. ota, ears; odous, tooth). An extinct genus of

Sharks.
OUDENODON (Gr. ouden, none; odous, tooth). A genus of Dicy-

nodont Reptiles.
OVIBOS (Lat. ovis, sheep; bos, ox). The genus comprising the

Musk-ox.

PACHYDERM ATA (Gr. pachus, thick; derma, skin). An old Mam-
malian order constituted by Cuvier for the reception of the
Rhinoceros, Hippopotamus, Elephant, etc.

PALE ASTER (Gr. palaios, ancient; aster, star). An extinct
genus of Star-fishes.

PALEOCARIS (Gr. palaios, ancient; karis, shrimp). An extinct
genus of Decapod Crustaceans.

PALEOLITHIC (Gr. palaios, ancient; lithos, stone). Applied to
the rude stone implements of the earliest known races of
men, to the men who made these implements, or to the period
at which they were made.

PALEONTOLOGY (Gr. palaios, ancient; and logos, discourse). The
science of fossil remains or of extinct organized beings.

PAL/EOPHIS (Gr. palaios, ancient; ophis, serpent). An extinct
genus of Snakes.

PALEOSAURUS (Gr. palaios, ancient; saura, lizard). A genus
of Thecodont Reptiles.

PALEOTHERIDE (Gr. palaios, ancient; therion, beast). A group of
Tertiary Ungulates.

PALEOZOIC (Gr. palaios, ancient; and zoe, life). Applied to
the oldest of the great geological epochs.

PARADOXIDES (Lat. paradoxus, marvellous). A genus of Trilo-
bites.

PATAGIUM (Lat. the border of a dress). Applied to the ex-
pansion of the integument by which Bats, Flying Squirrels,
and other animals support themselves in, the air.

PECOPTERIS (Gr. peko, I comb; pteris, a fern). An extinct genus
of Ferns.

PECTEN (Lat. a comb). The genus of Bivalve Molluscs com-
prising the Scallops.

PECTORAL (Lat. pectus, chest). Connected with, or placed upon,
the chest.

PENTACRINUS (Gr. penta, five; krinon, lily). A genus of Crinoids
in which the column is five-sided.

PENTAMERUS (Gr. penta, five; meros, part). An extinct genus
of Brachiopods.

PENTREMITES (Gr. penta, five; trenia, aperture). A genus of
Blastoidea, so-named in allusion to the apertures at the sum-
mit of the calyx.

PERENNIBRANCHIATA (Lat. perennis, perpetual ; Gr. brag chia, gill).
Applied to those Amphibia in which the gills are permanently
retained throughout life.

PERISSODACTYLA (Gr. perissos, uneven; daktulos, finger). Ap-
plied to those Hoofed Quadrupeds (Ungulata) in which the
feet have an uneven number of toes.

GLOSSARY. 409

PETALOID. Shaped like the petal of a flower.

PHACOPS (Gr. phakf, a lentil; ops, the eye). A genus of Trilo-

bites.
PHALANGES (Gr. phalanx, a row). The small bones composing

the digits of the higher Vertebrata. Normally, each digit

has three phalanges.
PHANEROGAMS (Gr. phaneros, visible; gamos, marriage). Plants

which have the organs of reproduction conspicuous, and which

bear true flowers.
PHARYNGOBRANCHII (Gr. pharugx, pharynx; bragchia, gill). The

order of Fishes comprising only the Lancelet.
PHASCOLOTHERIUM (Gr. phaskolos, a pouch; therion, a beast).

A genus of Oolitic Mammals.
PHRAGMACONE (Gr. phragma, a partition; and konos, a cone).

The chambered portion of the internal shell of a Belemnite.
PHYLLOPODA (Gr. phullon, leaf; and pous, foot). An order of

Crustacea.

PINNATE (Lat. pinna, a feather). Feather-shaped; or possess-
ing lateral processes.
PINNIGRADA (Lat. pinna, a feather; gradior, I walk). The group

of Carnivora, comprising the Seals and Walruses, adapted

for an aquatic life. Often called Pinfiipedia.
PINNULE (Lat. dim. of pinna). The lateral processes of the

arms of Crinoids.
PISCES (Lat. piscis, a fish). The class of Vertebrates comprising

the Fishes.
PLACOID (Gr. plax, a plate; eidos, form). Applied to the

irregular bony plates, grains or spines which are found in the

skin of various fishes (Elasmobranchii).
PLAGIOSTOMI (Gr. plagios, transverse; stoma, mouth). The

Sharks and Rays, in which the mouth is transverse, and is

placed on the under surface of the head.

PLATYCERAS (Gr. plains, broad; keras, horn). A genus of Uni-
valve Molluscs.
PLATYCRINUS (Gr. plains, broad; krinon, lily). A genus of

Crinoidea.
PLATYRHINA (Gr. plains, broad; rhines, nostrils). A group of

the Quadrumana.
PLATYSOMUS (Gr. plains, wide; soma, body). A genus of Ganoid

Fishes.
PLEISTOCENE (Gr. pleistos, most; kainos, new). Often used as

synonymous with " Post-Pliocene. "
PLEUROTOMARIA (Gr. pleura, the side; tome", notch). A genus

of Univalve shells.
PLIOCENE (Gr. pleion, more; kainos, new). The later Tertiary

period.
PLIOPITHECUS (Gr. pleion, more; pithekos, ape). An extinct

genus of Monkeys.
PLIOSAURUS (Gr. pleion, more; saura, lizard). A genus of

Plesiosaurian Reptiles.
POLYCYSTINA (Gr. polus, many; and kustis, a cyst). An order

of Protozoa with foraminated siliceous shells.
POLYPARY. The hard chitinous covering secreted by many of

the Hydrozoa.

410 GLOSSARY.

POLYPE (Gr. polus, many; pous, foot). Restricted to the single
individual of a simple Actinozoon, such as Sea-anemone, or
to the separate zooids of a compound Actinozotin. Often ap-
plied indiscriminately to any of the Ccelenterata, or even to
the Polyzoa. N

POLYPORA (Gr. polus, many; poros, a passage). A genus of
Lace-corals (Fenestellida.}

POLYTHALAMOUS (Gr. polus \ and thalamos, chamber). Having
many chambers; applied to the shells of Foraminifera and
Cephalopoda.

POLYZOA (Gr. polus; and zo'6n, animal). A division of the
Molluscoida comprising compound animals, such as the Sea-
mat — sometimes called Bryozoa.

PORIFERA (Lat. porus, a pore; and fero, I carry). Sometimes
used to designate the Foraminifera, or the Sponges.

PR^EMOLARS (Lat. pros, before; molar es, the grinders). The
molar teeth of Mammals which succeed the molars of the
milk-set of teeth. In man, the bicuspid teeth.

PROBOSCIDEA (Lat. proboscis, the snout). The order of Mam-
mals comprising the Elephants.

PROCCELOUS (Gr. pro, before; koilos, hollow). Applied to ver-
tebrae the bodies of which are hollow or concave in front.

PRODUCTA (Lat. productus, drawn out or extended). An extinct
genus of Brachiopods, in which the shell is " eared, " or has
its lateral angles drawn out.

PROTICHNITES (Gr. protos, first; ichnos, footprint). Applied to
certain impressions in the Potsdam sandstone of North Amer-
ica, believed to have been produced by large Crustaceans.

PROTOPHYTA (Gr. protos; and phut on, plant). The lowest
division of plants.

PROTOPLASM (Gr. protos; and plasso, I mould). The elementary
basis of organized tissues. Sometimes used synonymously for
the " sarcode " of the Protozoa.

PROTOROSAURUS or PROTEROSAURUS (Gr. protos, first; orao, I se«
or discover; saura, lizard; or proteros, earlier; saura, lizard).
A genus of Permian lizards.

PROTOZOA (Gr. protos; and zoon, animal). The lowest division
of the animal kingdom.

PSAMMODUS (Gr. psammos, sand; odous, tooth). An extinct
genus of Cestraciont Sharks.

PSEUDOPODIA (Gr. pseudos, falsity; and pous, foot). The exten-
sions of the body-substance which are put forth by the Rhizo-
poda at will, and which serve for locomotion and prehension.

PSILOPHYTON (Gr. psilos, bare; phuton, plant). An extinct genus
of Lycopodiaceous plants.

PTERANODON (Gr. pteron, wing; a, without; odous, tooth). A
genus of Pterosaurian ^Reptiles.

PTERASPIS (Gr. pteron, wing; aspis, shield). A genus of Ganoid
Fishes.

PTERICHTHYS (Gr. pteron, wing; ichthus, fish). A genus of
Ganoid Fishes.

PTERODACTYLUS (Gr. pteron, wing; daktulos, finger). A genus
of Pterosaurian Reptiles.

GLOSSARY. 411

PTEROPODA (Gr. pteron, wing; and pous, foot). A class of the

Mollusca which swim by means of fins attached near the

head.
PTEROSAURIA (Gr. pteron, wing; saura, lizard). An extinct order

of Reptiles.
PTILODICTYA (Gr. ptilon, a feather; diktuon, a net). An extinct

genus of Polyzoa.
PTYCHOCERAS (Gr. ptuche*, a fold; keras, a horn). A genus of

Ammonitidcz

PULMONATE. Possessing lungs.
PYRIFORM (Lat. pyrus, a pear; and forma, form). Pear-shaped.

Q

QUADRUMANA (Lat. quatuor, four; manus, hand). The older
of Mammals comprising the Apes, Monkeys, Baboons, Lemurs,
etc.

R

RADIATA (Lat. radius, a ray). Formerly applied to a large
number of animals which are now placed in separate sub-
kingdoms (e. g., the Coclenterata, the Ecliinodermata, the/n-
fusoria, etc.)

RADIOLARIA (Lat. radius, a ray). A division of Protozoa.

RAMUS (Lat. a branch). Applied to each half or branch of the
lower jaw, or mandible, of Vertebrates.

RAPTORES (Lat. rapto, I plunder). The order of the Birds of
Prey.

RASORES (Lat. rado, I scratch). The order of the Scratching
Birds (Fowls, Pigeons, &c.)

RECEPTACULITES (Lat. receptaculmn, a storehouse). An extinct
genus of Protozoa.

REPTILIA (Lat. repto, I crawl). The class of the Vertebrata
comprising the Tortoises, Snakes, Lizards, Crocodiles, etc.

RETEPORA (Lat. rete, a net; porus, a pore). A genus of Lace-
corals (Polysoa).

RHAMPHORHYNCHUS (Gr, rhamphos, beak; rhugchos, nose). A
genus of Pterosaurian Reptiles.

RHINOCEROS (Gr. rhis, the nose; keras, horn). A genus of
Hoofed Quadrupeds.

RHIZOPODA (Gr. rhiza, a root; and pous, foot). The division of
Protozoa comprising all those which are capable of emitting
pseudopodia.

RHYNCHOLITES (Gr. rhugchos, beak; and lithos, stone). Beak-
shaped fossils consisting of the mandibles of Cephalopoda.

RHYNCHONELLA (Gr. rhugchos, nose or beak). A genus of
Brachiopods.

RODENTIA (Lat. rodo, I gnaw). An order of the Mammals;
often called Glires (Lat. glis, a dormouse).

ROTALIA (Lat. rota, a wheel). A genus of Foraminifera.

RUGOSA (Lat. rugosus, wrinkled). An order of Corals.

RUMINANTIA (Lat. ruminor, I chew the cud). The group of
Hoofed Quadrupeds (Ungulata) which "ruminate" or chew
the cud.

412 GLOSSARY.

S

SARCODE (Gr. sarx, flesh; eidos, form). The jelly-like substance
of which the bodies of the Protozoa are composed. It is an
albuminous body containing oil-granules, and is sometimes
called " animal protoplasm. "

SAURIA (Gr. saura, a lizard). Any lizard-like Reptile is often
spoken of as a " Saurian ; " but the term is sometimes re-
stricted to the Crocodiles alone, or to the Crocodiles and
Larcertilians.

SAUROPTERYGIA (Gr. saura; pterux, wing). An extinct order
of Reptiles, called by Huxley Plesiosauria, from the typical
genus Plesiosaurus.

SAURUR^E (Gr. saura; oura, tail). The extinct order of Birds
comprising only the Archocopteryx.

SCANSORES (Lat. scando, I climb). The order of the Climbing
Birds (Parrots, Woodpeckers, &c.)

SCAPHI (Lat. scapha, a boat). A genus of the Ammonitida.

SCOLITHUS (Gr. skolex, a worm; lithos, a stone). The vertical
burrows of sea-worms in rocks.

SCUTA (Lat. scutum, a shield). Applied to any shield-like plates ;
especially to those which are developed in the integument of
many Reptiles.

SELACHIA or SELACHII (Gr. selachos, a cartilaginous fish, probably
a shark). The sub-order of Elasmobranchii comprising the
Sharks and Dog-fishes.

SEPIOSTAIRE. The internal shell of the Sepia, commonly known
as the " cuttle-bone. "

SEPTA. Partitions.

SERPENTIFORM. Resembling a serpent in shape.

SERTULARIDA (Lat. sertutn, a wreath). An order of Hydrozoa.

SESSILE (Lat. sedo, I sit). Not supported upon a stalk or ped-
uncle; attached by a base.

SET^: (Lat. bristles). Bristles orjong stiff hairs.

SIGILLARIOIDS (Lat. sigilla, little images). A group of extinct
plants of which Sigillaria is the type, so-called from the seal-
like markings on the bark.

SILICEOUS (Lat. silex, flint). Composed of flint.

SINISTRAL (Lat. sinistra, the left hand). Left-handed; applied
to the direction of the spiral in certain shells, which are said
to be " reversed. "

SIPHON (Gr. a tube). Applied to the respiratory tubes in the
Mollusca; also to other tubes of different functions.

SIPHONIA (Gr. siphon, a tube). A genus of fossil Sponges.

SIPHONOSTOMATA (Gr. siphon; and stoma, mouth). The division
of Gasteropodous Molluscs in which the aperture of the shell
is not " entire, " but possesses a notch or tube for the emission
of the respiratory siphon.

SIPHUNCLE (Lat. siphunculus, a little tube). The tube which
connects together the various chambers of the shell of certain
Cephalopoda (e. g., the Pearly Nautilus).

SIRENIA (Gr. seiren, a mermaid). The order of Mammalia com-
prising the Dugongs and Manatees.

GLOSSARY. 413

SIVATHERIUM (Siva, a Hindoo deity; Gr. therion, beast). An
extinct genus of Hoofed Quadrupeds.

SOLIDUNGULA (Lat. solidus, solid; ungula, a hoof). The group
of Hoofed Quadrupeds comprising theHorse, Ass, and Zebra,
in which each foot has only a single solid hoof. Often called
Solipedia.

SPHENOPTERIS (Gr. sphe*n, a wedge; pteris, a fern). An extinct
genus of ferns.

SPICULA (Lat. spiculum, a point). Pointed needle-shaped bodies.

SPIRIFERA (Lat. spira, a spire or coil; fero, I carry). An ex-
tinct genus of Brachiopods, with large spiral supports for the
" arms. "

SPIRORBIS (Lat. spira, a spire; prbis, a circle). A genus of tube-
inhabiting Annelides, in which the shelly tube is coiled into
a spiral disc.

SPONGIDA (Gr. spoggos, a sponge). The division of Protozoa,
commonly known as sponges.

STALACTITES (Gr. stalasso, I drop). Icicle-like encrustations and
deposits of lime, which hang from the roof of caverns in
limestone.

STALAGMITE (Gr. stalagma, a drop). Encrustations of lime
formed on the floor of caverns which are hollowed out of
limestone.

STIGMARIA (Gr. stigma, a mark made with a pointed instru-
ment). A genus founded on the roots of various species
of Sigillaria.

STRATUM (Lat. stratus, spread out; or stratum, a thing spread
out). A layer of rock.

STROMATOPORA (Gr. stroma, a thing spread out; poros, a pas-
sage or pore). A Palaezoic genus of Protozoa.

STROPHOMENA (Gr. strophao, I twist; wienf, moon). An ex-
tinct genus of Brachiopods.

SUB-CALCAREOUS. Somewhat calcareous.

SUB-CENTRAL. Nearly central, but not quite.

SUTURE (Lat. suo, I sew). The line of junction of two parts
which are immovably connected together. Applied to the line
where the whorls of a univalve shell join one another; also
to the lines made upon the exterior of the shell of a
chambered Cephalopod by the margins of the septa.

SYRINGOPORA (Gr. surigx, a pipe; poros, a pore). A genus of
Tabulate Corals.

TABULA (Lat. tabula, a tablet). Horizontal plates or floors

found in some Corals, extending across the cavity of the

" theca " from side to side.
TEGUMENTARY (Lat. tegumentum, a covering). Connected with

the integument or skin.
TELEOSAURUS (Gr. teleios, perfect; saura, lizard). An extinct

genus of Crocodilian Reptiles.
TELEOSTEI (Gr. teleios, perfect; osteon, bone.) The order of the

" Bony Fishes."

414 GLOSSARY.

TELSON (Gr. a limit). The last joint in the abdomen of Crus-
tacea; variously regarded as a segment without appendages, or
as an azygous appendage.

TENTACULITES (Lat. tentaculum, a feeler). A genus of Ptero-
poda.

TERERBRATULA (Lat. terebratus, bored or pierced.) A genus of
Brachiopoda, so called in allusion to the perforated beak of
the ventral valve.

TEST (Lat. testa, shell.) The shell of Mollusca, which are for
this reason sometimes called " Testacea," also, the calcareous
case of Echinoderms; also, the thick leathery outer tunic in
the Tunic at a.

TESTACEOUS. Provided with a shell or hard covering.

TESTUDINJD^E (Lat tesiudo, a tortoise). The family of the Tor-
toises.

TETRABRANCHIATA (Gr. tetra, four; bragchia, gill). The order
of Cephalopoda characterized by the possession of four gills.

TEXULARIA (Lat. texilis, woven). A genus of Foraminifera.

THECA (Gr. the'ke, a sheath). A genus of Pteropods.

THECODONTOSAURUS (Gr. theke, a sheath; odous, tooth; saura,
lizard). A genus of " Thecodont " Reptiles, so named in allu-
sion to the fact that the teeth are sunk in distinct sockets.

THERIODONT (Gr. tlrtrion, a beast; odous, tooth). A group _of
Reptiles so named by Owen in allusion to the Mammalian
character of their teeth.

THORAX (Gr. a breastplate). The region of the chest.

THYLACOLEO (Gr. thulakos, a pouch; leo, a lion). An extinct
genus of Marsupials.

TRIGONIA (Gr. treis, three; gonia, angle.) A genus of Bivalve
Molluscs.

TRIGONOCARPON (Gr. treis, three; gonia, angle; karpos, fruit).
A genus founded on fossil fruits of a three-angled form.

TRILOBITA (Gr. treis, three; lobos, a lobe). An extinct order of
Crustaceans.

TRINUCLEUS (Lat. iris, three; nucleus, a kernel.) A genus of
Trilobites.

TROGONTHERIUM (Gr. trogo, I gnaw; therion, beast.) An extinct
genus of Beavers.

TUBICOLA (Lat tuba, a tube; and colo, I inhabit). The order of
Annelida which construct a tubular case in which they protect
themselves.

TUBICOLOUS. Inhabiting a tube.

TUNICATA (Lat. tunica, a cloak). A class of Molluscoida which
are enveloped in a tough leathery case or " test."

TURBINATED (Lat. turbo, a top). Top-shaped; conical with a
round base.

TURRILITES (Lat. turns, a tower). A genus of the Ammoni-
tida.

U

UMBO (Lat. the boss of a shield). The beak of a bivalve shell.
UNGUICULATE (Lat. unguis, nail). Furnished with claws.

GLOSSARY. 415

UNGULATA CLat.-*ungula, hoof). The order of Mammals com-
prising the Hoofed Quadrupeds.

UNGULATE. Furnished with expanded nails constituting hoofs.

UNILOCULAR (Lat. unus, one; and loculus, a little purse. Possess-
ing a single cavity or chamber. Applied to the shells of Fora-
minifera and Mollusca.

UNIVALVE (Lat. unus, one; valvcc, folding-doors). A shell com-
posed of a single piece or valve.

URODELA (Gr. our a, tail; delos, visible). The order of the Tailed
Amphibians (Newts, etc.).

VENTRAL (Lat. venter, the stomach). Relating to the inferior
surface of the body.

VENTRICULITES (Lat. ventriculum, a little stomach). A genus
of siliceous Sponges.

VERMIFORM (Lat. vermis, worm; and forma, form). Worm-like.

VERTEBRA (Lat. verto, I turn). One of the bony segments of the
vertebral column or backbone.

VERTEBRATA (Lat. vertebra, a bone of the back, from verier e, to
turn.) The division of the Animal Kingdom roughly character-
ized by the possession of a backbone.

VESICLE (Lat. vesica, a bladder). A little sac or cyst.

W

WHORL. The spiral turn of a univalve shell.

X

XIPHOSURA (Gr. xiphos, a sword; and oura, tail). An order of
Crustacea, comprising the Limuli or King-Crabs, characterized
by their long sword-like tails.

XYLOBIUS (Gr. xulon, wood; bios, life). An extinct genus of
Myriapods, named in allusion to the fact that the animals lived
on decaying wood. /

ZAPHRENTIS (proper name). A genus of Rugose Corals.

ZEUGLODONTID^E (Gr. zeugle', a yolk; odous, a tooth). An extinct
family of Cetaceans, in which the molar teeth are two-fanged,
and look as if composed of two parts united by a neck.

ZOOPHYTE (Gr. coon, animal; phuton, plant). Loosely applied
to many plant-like animals, such as Sponges, Corals, Sea-
anemones, Sea-mats, etc.).

INDEX.

Acadian Group, 79.

Acer, 320.

Acervularia, 121, 176.

Acidaspis, 126.

Acorn-shells, 275.

Acroculia, 130.

Acrodus, 220, 249, 283 ; nobilis, 249.

Acrotreta, 112.

Acroura, 122.

Actinocrinus, 178.

jEglina, 110.

jEpiornis, 361.

Agnostus, 85-87, 109; rex, 85.

^4 ices male his, 368.

^Zecfo, 110.

Alethopteris, 138, 167, 200.

^4Za# (see Sea- weeds).

Alligators, 224, 307.

.4Znws, 270.

Amblypterus, 192 ; macropterus, 192.

Ambonychia, 112.

Ammonites, 191, 218-220, 244-246, 280;
Humphresianus, 245; bifrons, 245.

Ammonitidse, 246, 280, 294, 304.

Amphibia, 193; of the Carboniferous,
193-195; of the Permian, 204; of the
Trias, 221-223 ; of the Jurassic, 249 ;
of the Miocene, 324.

Amphicyon, 333.

Amphilestes, 261.

Amphispongia, 120.

Amphistegina, 322.

Amphitherium, 261, 262; Prevostii. 261.

Amphitragulus, 328.

_<4rapZea;w», 177; coralloides, 178.

Ampyx, 110.

Ananchytes, 275.

Anchitherium, 311, 312.

Ancyloceras, 280, 281 ; Matheronianus,
281.

Ancylotherium Pentelici, 326.

Andrias Scheuchzeri, 324, 325.

Anglosperms, 269, 271.

Animal Kingdom, divisions of, 389-
392.

Anisopus, 211.

Annelida, of the Cambrian period,
82, 84 ; of theiLower Silurian 109 ; of
the Upper Silurian, 124, 125; of the
Devonian, 146, 147; of the Carbon-
iferous, 181.

Annularia, 139, 200, 212.

Anomodontia, 226.

Anoplotheridse, 313.

Anoplotherium, 813 ; commune, 313.

Ant-eaters, 309, 326, 363, 364, 366.

Antelopes, 328.

Anthracosaurus, Russelli, 194.

Ahthrapalaemon gracilis, 184.

Antilocapra, 330.

Antilope quadricornis, 320.

Antwerp Crag, 336.

Apes, 334.

Apiocrinus, 238.

Apteryx, 359, 361.

Aqueous rocks, 15.

Arachnida of the Coal-measures, 185,

Aralo-Caspian Beds, 337.

Araucaria, 270.

Araucarioxylon, 173.

Jrra, 203; anliqua, 203.

Archseocidaris, 182.

Archseocyathus , 82.

Archseopteryx, 260, 290; macrura, 259

260.

Archxosphserinse, 75.
Archimedes. 187 ; Wortheni, 187.
Arhciulus, 185.

Arctic regions, Miocene flora of, 321.
Arctocyon, 315.
Arenaceous rocks, 21.
Arenicolites, 83; didymus, 88.
Arenig rocks, 93, 95.
Argillaceous rocks, 21.
Armadillos, 309,863, 366.
Artiodactyle Ungulates, 313, 328.
Asaphus, 110;tyranmts, 108, 110.
Ascoceras, 132.
Aspidella, 76.
Aspidura loricata. 215.
Astarte borealis, 351.
Asterophyllites, 139, 200.
Asterosteus, 153.
^sfranda?, 238.
Astrxospongia, 120, 141.
Astylospongia, 99; prxmorsa, 99.
Athyris, 112, 130, 149,202; subtil ita,189.
Atlantic Ooze, 23, 24.
Atrypa, 130: congcsta, 129; hemisphx-

rica, 130 ; reticularis, 149, 150.
Auger-shells. 303.
Aurochs, 370.

(416)

INDEX.

417

Aves (see Birds).

Avicula, 242 ; contora, 216, 217 ; socialis,

217.

"Avicula contorta Beds," 209, 217.
Aviculidx, 203, 277.
Aviculopecten, 190.
Axophyllum, 176.
Aymestry Limestone, 117, 119.
Azoic rocks, 67.

Baculites, 281 ; anceps, 282.

Bagshot and Bracklesham Beds, 297.

Bakewellia, 203.

Balxna, 326.

Bala Group, 93, 95.

Bala Limestone, 94.

Balanidas, 275.

Banksia, 270. 320.

Barbadoes Earth, 34.

Barnacles, 275.

Bath Oolite. 234.

Bats, 315, 334.

Bears, 342, 373.

Beaver, 334,349.

Beetles, 185, 322.

Belemnitella mucrnnata, 283.

Belemnites, 219, 247, 283; canaliculatus,
248.

Belemnitidff, 247, 294.

Belemnotevthis, 247.

Belinurus, 182.

Bellerophon, 113,131, 151,193; Argo.llZ.

Belodon, 224 ; Carolinensis, 225.

Belosepia, 305.

Beloteuthis subcostata, 247.

Bembridge Beds, 297.

Beryx, 284 ; Lewesiensis, 284.

Bcyrichia, 108; complicata, 108.

Bird's eye Limestone, 96,97.

Birds, of the Trias, 228; of the Juras-
sic, 259-261; of the Cretaceous, 289,
290; of the Eocene, 307; of the Post-
Pliocene, 358-361.

Bison prisons, 370.

Bituminous Schists of Caithness, 37.

Bivalves (see Lamellibranchiata).

Black-lead (see Graphite).

Black-River Limestone, 96,97.

Blastoidea, 179; of the Devonian, 145;
of the Carboniferous, 179.

Boidse, 306.

Bolderberg Beds, 317.

Bone-bed, of the Upper Ludlow, 118;
of the Trias, 230.

Bony Fishes (see Teleostean Fishes).

Bos primtgenius, 36Q; taunts, 369.

Boulder-clay, 350.

BourgueUcrinus, 274.

Bovey- Tracy Beds, 316, 320.

Brachiopoda, 127; of the Cambrian
rocks, 87 ;of the Lower Silurian , 109-
11 1; of the Upper Silurian. 127-130;
of the Devonian, 149, 150; of the Car-
boniferous, 188-190 ; of the Permian,
202; of the Trias, 216; of the Juras-
sic, 241 ; of the Cretaceous, 267; of
the Eocene. 302.

Bnehymetopug, 183.

Brachyurous Crustaceans, 184, 202.

Bradford Clay, 234.

Breaks in the Geological and Pal-
seontological record, 45-53.

Breccia, 20.

Brick-earths, 352.

Bridlington Crag, 336, 337, 349.

Brittle-stars (s^eOphiuroidea).

Bronteus, 146.

Brontothcridte, 327.

Brontotherium ingens, 327.

Brontozoum, 211.

Buccinum, 244.

Bucklandia, 237.

Bulimus, 304.

Bunter Sandstein,208, 209, 211.

Butterflies, 241, 322.

Byssoarca, 203.

Cainozoic (see Kainozoic).

Calamaries, 247.

CalamiteSj 167, 168, 200; cannsrformia,

169.

Calcaire Grossier, 297, 298.
Calcareous rocks, 21-83; Tufa, 22.
Calciferous Sand-rocK, 96, 97.
Calveria, 181.

Calymene, 110, 126: Blumcnbachii, 108.
Camarophoria globulin a 202.
Cambrian period. 77-91; rocks of, in

Britain, 77, 78; in Bohemia 79; in

North America, 79; life of, 80-91.
Ccanelopardalidx, 328.
Camels, 328, 368.
Cam's lupus, 319; Parisiensis, 315.
Caradoc rocks, 93, 95, 97.
Carbon, origin of, 37.
Carboniferous Limestone, 161, 162.
Carboniferous period, 160-193; rocks

of, 160-163 ; life of, 163-192.
Carboniferous Slates of Ireland, 137,

161, 162.

Carcharias, 283.

Carcharodon, ZQ5,323;productus, 324.
Cardinia, 242.
Cardiocarpon, 139.
Cardiola, 130 ; fibrosa, 130 ; interrupts,

130.

Cardita, 219, 30^; planicosta, 302, 303.
Cardium, 302 ; Rhxticum, 216, 217.
Caribou, 369.
Carnivora, of the Eocene, 315; of the

Miocene, 333: of the Pliocene, 341,

342; of the Post-Pliocene, 373-375.
Caryocaris,WS, 109.
Caryoerinus ornatus, 107.
Castor fiber, 349.
Castoroides Ohioensis. 375.
Catastrophism, theory of, 3.
Catopterus, 220.
Cauda-Galli Grit. 137,139.
Caulopteris, 138, 167.
Cave-bear, 373.

Cave-deposits, 350, 352, 354, 356.
Cave-hyaena, 374.
Cave-lion, 375.
Caves, formation of, 354 ; deposits in,

356.

Cavicornia, 329.
Cement-stones, 32.
Cephalaspis, 154.
Cephalopoda, of the Cambrian period,

89; of the Lower Silurian, 1 3-116;

of the Upper Silurian, 132; of the

Devonian, 151 ; of the Carbonifer-

4i8

INDEX.

ous, 189. 191; of the Permian, 203;
of the Trias. 217; of 'the Jurassic,
246-249; of the Cretaceous, 280-2<^3;
of Eocene, 304 ; of the Miocene, 323.

Ceratiocaris, 109.

Ceratitcs, 218-219; nodosus 218.

Ceratodun, 220; attus, 220; Fosteri, 220,
221, 2(52 ; scrratus, 220.

Ceriopora, 148; Hamiltonensis, 148.

Ceritnium, 219, 303 ; hexagonum, 304.

Cervidx, of the Miocene period, 328;
of the Pliocene, 340; of the Post-
Pliocene, 368, 369.

Cervus, 328 ; capreolus, 349, 368 , elaphus,
349, 368; megaceros, 368; tarandus,
368.

Cestracinn Philippi, 192, 262.

Cestracionts, of the Devonian, 156;
of the Carboniferous, 192; of the
Permian, 203; of the Trias, 220; of
the Jurassic, 252; of the Creta-
ceous, 283.

Cetacea, 309; of the Eocene, 309; of
the Miocene, 326.

Cetiosaurus, 256, 257.

Chxropotamus, 313.

Chce,tctes, 106, 177 ; tumidus 178.

Chain-coral, 121.

Chalk, 267; structure of, 22-24 ; fora-
minifera of, 26, 272; origin of, 24;
with flints, 267; without flints, 267.

Chama, 243.

Chamcerops, 319; Helvetica, 319.

Chazy Limestone, 96, 97.

Cheiroptera, of the Eocene, 315, 316; of
the Miocene, 334.

Cheirotherhim, 221, 222.

Cheirurus, 110, 126; bimucronatus, 126.

Chelichnus Duncani, 207.

Chelone Benstedi, 289; planiceps, 260.

Chelonia, of the Permian, 207; of the
Jurassic, 259; of the Cretaceous,
289 ; of the Eocene, 306.

Chcmnitzia, 219.

Chemung Group, 137, 138, 139.

Chert, 35.

Chillesford Beds, 336, 338, 349.

Chonetes, 130, 149, 188; Hardrensis, 189.

Chonophyllum, 176.

Ciclaris, 275.

Cincinnati Group, 96, 97.

Cinnamomum polymorphum, 320.

Cinnamon-trees, 270, 300, 316, 320.

Cladodus, 192.

Claibome Beds, 299.

Clathropora, 148; intertexta, 148.

Clay, 21; Red, origin of, 36.

Clay-ironstone, nodules of, 32.

Cleidophorns, 112.

Cleodora, 323.

Climacograptus, 103, 121.

Clinton Formation, 118, 119.

Clisiophyllum, 177.

Clupeidse, 284.

Clymenia, 52; Scdawickii, 151.

Coal, 37; structure of, 166; mode of
formation of, 16>.

Coal-measures, 12, 163; mineral
characters of. 162 ; mode of forma-
tion of. 163. 165; plants of, 167-173.

Coccoliths, 269.

Coccosteus, 153, 154.

Cochiiodus, 192: contortus, 193.

Coleoptera, 185, 322.

Colossochelys Atlas, 324.

Columnaria, 106; alveolata, 106.

Comatula, 239, 274.

Conclusions to be drawn from Fos-
sils, 53-58.

Concretions, calcareous, 31; phos-
phatic, 32; of clay-ironstone, 32; of
manganese, 33.

Conglomerate, 19.

Coniferse, 270; wood of, 14; of Devon-
ian period, 140; of the Carbonifer-
ous, 174; of the Permian, 200; of the
Trias, 213; of the Jurassic period,
237.

Coniston Flags and Grits, 117.

Connecticut Sandstones, footprints
of, 228, 360.

Conocoryphe Mathcwi, 85; Sultzeri, 85.

Conodonts, 116, 133.

Constellaria, 106.

Constricting serpents of the Eocene,
306.

Contemporaneity of strata, 45-47.

Continuity, theory of, 5-8.

Conularia, 112, 131, 151, 190, 203, 244; or-
nata, 151.

Conulus, 190.

Convs, 803.

Coomhola Grits, 161, 162.

Coprolites, 32, 250.

Coralline Crag, 335.

Corallines, 26.

Coralliitm, 322.

Coral-rag, 2K4, 237, 238.

Coral-reefs, 25-28.

Coral-rock, 27.

Coral-sand, 20, 27.

Corals, 104; of the Lower Silurian,
1(K 107; of the Upper Silurian, 122;
of the Devonian, 142-145; of the
Carboniferous, 176-178; of the Per-
mian, 201; of the Trias, 214; of the
Jurassic, 235, 237; of the Cretaceous,
274; of the Eocene, 302; of the Mio'
cene, 322.

Corbula, 242.

Cornbrash. 234, 235.

Corniferous Limestone, 137, 139.

Cornulites, 12-x

Cornus, 27o.

Coryphodon, 310.

Cowries, 267, 280. 303.

Crabs, 184, 20J. 240, 275.

Crae, Red, 335; White, 335; Norwich,
336; Antwerp. 33C: Bridlington, 336;
Coralline, 335.

Crania, 112, 129, 202, 277; Ignaber gen-
sis. 277.

Crassatella, 302.

Crepiflophyllum, 141; Archiaci, 144.

Cretaceous period, 264-292; rocks of,
in Britain, 264-267; in North Amer-
ica 268. 269; life of, 2(19-292.

Crinoidal Limestone, 25, 26.

Crinoidea, 123; of the Cambrian, 82;
of the Lower Silurian, 106; of the
Upper Silurian, 122-124; of the De-
vonian, 145; of the Carboniferous,
177; of the Permian, 201; of the
Trias, 215; of the Jurassic, 238; of

INDEX.

419

the Cretaceous, 274; of the Eocene,
302.

Crioceras, 281; cristatum, 282.

Crocodilia, 224; of the Trias, 224; of the
Jurassic, 259; of the Cretaceous,
289; of the Eocene, 307.

Cromer Forest-bed, 348.

Crossozamites, 237.

Crotalocrinus, 125.

Crustacea, of the Cambrian, 84-88; of
the Lower Silurian, 108, 109; of the
Upper Silurian, i25-126- of the De-
vonian, 146, 148; of the Carbonifer-
ous, 182-185; of the Permian, 201;
of the Trias, 215; of the Jurassic,
240, of the Cretaceous, 275.

Cryptogams, 167, 270.

Ctenacanthus, 192,

Ctenodonia, 112.

Cupressus, 270.

Cursores, 307, 359.

Cuttle-fishes (see Dibranchiate Cep-
halopods).

Cyathocrinus, 178.

Cyathophyllirm, 121, 144, 177.

Cycadopteris, 270.

Cycads, 213; of the Carboniferous,
174; of the Permian, 201; of the
Trias, 213; of the Jurassic, 237; of
the Cretaceous, 270.

Cyclas, 277.

Cyclonema, 131,

Cyclophthalmus senior, 185.

C'yclostoma, 304; Arnotldii, 304.

Cynodraco, 226.

Cyprsea, 280, 303; cleganx, 303.

Cypress, 270. 320, 322.

Cypridina, 146.

Cypridina Slates.

Cyrena, 242, 277, 802.

Cyrtina, 219. 220.

Cyrtoceras, 115.

Cysttphyllum,l2l, 144, \1S\vesiculosum,
143.

Cystoidea, 106-109; of the Cambrian,
82; of the Lower Silurian, 108; of
the Upper Silurian, 122.

Dachstein Beds, 210, 211.

Dadoxylon, 140, 173.

Daonella, 216; Lommelli, 216.

Dasornis Londinensis, 307.

Decapod Crustaceans, 183.

Deer, 328, 340, 368.

Deinosauria, 255; of the Trias, 227; of
the Jurassic, 255-258; of the Creta-
ceous, 285-287.

Deinotherium, 331, 332; giganteum. 331.

Denbighshire Flags and Grits, 117.

Dendrocrinus, 82.

Dendrograptus. 101.

Desmids, 141, 269.

Devonian Formation, 135-139: origin
of name, 135; relation to Old Red
Sand-stone, 135-136; of the Devon-
shire, 135; of Nc-'-th Ame.ica, 135,
136; life of, 137-158.

Diadema, 275.

Diatoms, 34; of the Devonian, 140; of
the Carboniferous, 167; of flints,
269; of Richmond Earth, 34, 318.

Dibranchiate Cephalopods, 114; of
the Trias, 217; of the Jurassic, 244-
246; of the Cretaceous, 283, 284; of
the Eocene, 805; of the Miocene,
323.

Dicer as, 243; arietina, 243.

Diceras Limestone, 234, 243.

Dichobune, 313.

Dichograptus, 102; octobrachiatus, 102.

Dicotyledonous plants, 270.

Dicotyles antiquus, 328.

Dicranograptus, 103, 121.

Dictyonema, 89, 101, \1\\sociale, 89.

Dicynodon, 227; lacerticeps, 226.

Didelphys, 262, 326; gypsorum, 309.

Didus ineptus, 361.

Didymograptus, 102; divaricatus, 103.

Dikellocephalus Celticux, 85; Minneso-
tensis, 85.

Dimorphodon, 254.

Dinichthys, 155; Hertzeri, 154.

Dinoceras, 314; mimbilis, 314.

Dinocerata, 314.

Dinophis, 306.

Dinornis, 359, 360; elephantopus, 360 ;

giganteiis, 361.

)inf>nauria

Dinosauria (see Dcinosauria).

Dinotherium (see Deinotherium).

Diphyphyllum, 144.

Diplograptus, 103, 121; prisiis, 103.

Dipnoi, 156, 196, 221.

Diprotodon, 362; australis, 362.

Diptera, 322.

Discina, 88, 112, 12p, 202.

Discoidea, 275; cylindrica,275.

Dithyrocaris, 183; Scouleri. 184.

Dodo, 361.

Dog-whelks, 303.

Dolomite, 29.

Dolomitic Conglomerate of Bristol,

206, 225.

Dolphins, 309, 326.
Dorcathcrium, 328.
Downton Sandstone, 117.
Draco volans, 252.
Dragon-flies 322.
Drift, Glacial, 349.
Dremotherium, 328.
Dromatherium sylvestre, 229, 231.
Dryandra, 270.
Dryopithecus, 334.
Dugongs, 309.

Echinodermata, of the Cambrian, 82;
of the Lower Silurian, 106; of the
Upper Silurian, 122; of the Devon-
ian, 145; of the Carboniferous, 177;
of the Permian, 200: of the Trias,
214; of the Jurassic, 238; of the Cre-
taceous, 274; of the Eocene, 302.

Echinoidea, 180; of the Upper Silu-
rian, 122; of the Devonian, 145; of
the Carboniferous, 181; of the Per-
mian, 201; of the Jurassic, 240; of
the Cretaceous, 274.

Edentata, 363; of the Eocene, 309; of
the Miocene, 326; of the Post-Plio-
cene, 363-367.

Edriocrinus, 125.

Eifel Limestone, 137.

Elasmobranchii (see Placoid Fishes).

Elasmosaiirus, 285.

42O

INDEX.

Elephants, 331, 332, 341.

Elephas, 341; Americanus, 371; anti-
quus, 341, 342, 349, 354, 370; Falcon-
eri, 373; Melitensis, 373; meridiona-
lis, 341, 349, 370; planifrons, 332;
primigenius, 352, 354, 369, 370.

Elk, 868; Irish, 368, 369.

ElUpsocephalus Hoffi, 85.

Elotherium, 328.

Emydidse, 306.

Emys, 289.

Enaliosaurians, 225, 249, 286.

Encrinital marble, 25.

Encrinurus, 126.

Encrinus liliiformis, 215.

Endogenous plants, 270.

Etidophyllum 176.

Endothyra, 175; Bailyi, 175.

Engis skull, 377.
'

Entomoconchus Scouleri, 183, 184.
Eocene period, 294; rocks of, in Brit-

ain, 296, 297; in France, 297; in

North America, 298, 399; life of,

299-316.

Eocidaris, 201.
Eophyton, 81; Linneanum, 81.
Eophyton Sandstone, 79.
Eosaurus Acadianus, 195.
Eozoic rocks, 67.
Eozoon Bavaricum, 76.
Eozoon Canadense, 68, 76; appearance

of, in mass, 69; minute structure

of, 70, 71; affinities of, with For-

aminifera, 72-73.
Ephemeridse, 147.
Equidx, 311, 312, 327, 340.
Equisetacese, 168.
Equisetites, 200.
Equus, 312; caballus, 367; excelsus, 340;

fossilis, 349, 367.
Eridophyllum, 144.
Eryon, arctiformis, 240, 241.
Eschara, 277.
Escharidse, 277.
Escharina, 277; Oceani, 277.
Estheria, 147, 183, 215; te?ie«a, 184.
Eucalyptocrinus, 124; polydactylus, 124.
Eucladia, 122.
Euomphalus, 130, 151, 190, 203, 219- dts-

oors, 131.
Euplectclla, 273.
Eitproops, 182.
European Bison, 370.
Eurypterida, 126, 182; of the Upper

Silurian, 126; of the Devonian, 146.
Even-toed Ungulates, 310, 328, 367.
Exogenous plants, 270.
Exogyra, 243; virgula, 243.
Extinction of species, 58, 59.

Fagus, 270.

Faluns, 317.

Fan-palms, 319.

Favistella, 106.

Parasites. 121. 145; Gothlandica, 145;

hemisphasrica, 145.
Faxoe Limestone, 267, 295.
.Fefa's au<7ws/r/.s,342; Zeo, 375;speZcea,374.
Fenestella, 110, 127, 148, 187, 202, 216;

cribrosa, 148; magnified, 148; re#-

jormis, 202.

Ferns, of the Devonian, 136; of the
Carboniferous, 167; of the Permian,
200; of the Trias, 212; of the Juras-
sic, 236; of the Cretaceous, 269.

Fig-shells, 303.

Fishes, 152; of the Upper Silurian,
132, 133; of the Devonian, 152-157; of
the Carboniferous, 191, 192; of the
Permian, 204, 205; of the Trias, 219,
220; of the Jurassic, 247-249; of the
Cretaceous, 283, 285; of the Eocene,
305, 306; of the Miocene, 323, 324.

Flint, 31: structure of, 35; origin of,
34; organisms of, 36, 141, 271; of
Chalk, 35, 266, 269.

Flora (see Plants).

Footprints of Cheirothcrium, 221, 222;
of the Triassic sandstones of Con-
necticut, 228.

Foraminifera, 23-25, 71-74; of the Cam-
brian, 82; of the Lower Silurian,
93; of the Carboniferous, 174, 176; of
the Permian, 201; of the Trias, 214;
of the Jurassic, 237; of the Creta-
ceous, 22, 23, 271; of the Eocene,
300; of the Miocene, 322; of the
Post-Pliocene, 350; of Atlantic
ooze, 22, 24; as builders of lime-
stone, 25, 26, 30; as forming green
sands, 36.

Forbesiocrinus, 179.

Forest-bed of Cromer, 348.

Forest-bugs, 322.

Forest-marble, 234.

Formation, definition of, 19; succes-
sion of, 43.

Fossiliferous rocks, 15-38; chrono-
logical succession of, 38-45.

Fossilization, processes of, 12-13.

Fossils, definition of, 11; distinctive,
of rock-groups, 39; conclusions to
be drawn from, 53-58; biological
relations of, 58-62.

Foxes, 315.

Fringe-finned Ganoids, 156.

Fucoidal Sandstone, 79, 80.

Fucoids, 80,98.

Fuller's Earth, 234, 236.

Fusulina, 175: cylindrica, 176.

Fusus, 244, 303.

Galeocerdo, 323.

Galerites, 275; albogalerus, 275.

Galestes,2fi2.

Ganoid Fishes, 152; of the Upper
Silurian, 132; of the Devonian, 152-
155; of the Carboniferous, 191, 192;
of the Permian, 202; of the Trias,
219; of the Jurassic, 249; of the Cre-
taceous, 283; of the Eocene, 305,

Gaspe Beds, 135.

Gasteropoda, of the Cambrian, 89; of
the Lower Silurian, 113; of the Up-
per Silurian, 130, 131; of the De-
vonian, 150; of the Carboniferous,
190; of the Permian, 204; of the
Trias, 218; of the Jurassic, 244, 245;
of the Cretaceous, 279; of the
Eocene. 303.

Gastornis Parisiensis 307.

Gault, 264, 267.

INDEX.

421

pper Silurian, 120, 121.
Oolite, 2S4, 236; Upper, 264, 266,

Gavial, 260, 307.

Genesee Slates, 137.

Geological record, breaks in the, 48-

56.

Giraffes, 328.
Glacial period, 33o; deposits of, 349,

3oO.

Glandulina, 322.
Glaucouite, 3f>, 74, 271.
Glaucojiomr, 127, 187; piilcherrima, 187.
Globe Crinoids (*<'< Cystoidea).
Globigerina,23, 24, 272.
Glutton, 374.
Glyptaster, 122.
Glyptocrinus, 125.
Gtyptodon, 3«5.3G6; davipcs, 366.
Glyptolcemus, 156.
Goats, 329.

Goniatltes, 132, 151, 191, 219; Jossx, 191.
Gorffonidse, 302.
Grallatores, ."07.
Graphite, 37; mode of occurrence of,

37. 68; origin of, 37.
Qraptolites, 90, 101; structure of, 101 ;

of the Lower Silurian, 101-104; of

the U
Great

268.

Greenland, Miocene, plants of, 321.
Greensand, Lower, 264, 268.
Greensands, origin of, 265.
Grevillea, 270, 320.
GriffltMdes, 183.
Grizzly Bear, 373.
Ground Sloths, 364.
Gryphoen, 243; incurva, 243.
•Guelph Limestone, 119.
Gulo ftttCttt, 374 ; spelivux, 373.
Guttenstein Beds, 210, 211.
Gymnospermous Exogens, 270.
Gypsum, 33, 197, 209.
Gyracanthv*. 192.
G'yroccras, 132.

JIadrosaurus, 287.

Jfdli.fhcrium, 309.

Hallstadt Beds, 210, 211.

Halobia, 216.

Hatysitcx, 121; agglomerata,'122; eaten-

Ktarid,}22.

Hamilton formation, 137, 139.
Hamites, 281 ; rotundus, 282.
Haplophlcbium Barnesi, 186.
Harlech Grits, 78. 79.
Harpes, 110, 126 ; ungula, 126.
Hastings Sands, 265.
Headon and Osborne series, 297, 298.
Heart-urchins, 322.
Hcliolites, 106, 121, 274.
Heliophyttum. 144, 176; exiguum, 143.
Helix, 304.

Helladotherium, 328.
Heloporafragilis, 128.
Hemicidaris crenularis, 240.
Hemiptera, 322.

Hemitrochizcvs paradoxus, 202.
Hempstead Beds, 316.
Hespe,rornis,29Q, 291; regroftft, 29L
Heteropoda, 112; of the Lower Silu-

rian, 112; of the Upper Silurian,

131 ; of the Devonian, 150; of the

Carboniferous, lcJ9.

Hinnites, 219.

Hipparion, 312,32^,340.

Hippodium, 242.

Hippopotamus, 313; amphibius, 328.

340; major, 3 11, 349, 367; Sivalensis,

329.

Ifippothoa, 110.
Hippurite Marble, 278.
Hlppuritcs, 278; Toucasiana, 279.
Hippuritidse, 278, 294.
Histioderma, 83.

Hollow-horned Ruminants, 329.
Holocystis elegans, 274.
Holopea, 131 ; subconica, 131.
Holopella, 131,219; obsolcta, 131.
Holoptychius, 156 ; nobilisstmun, 158.
Holostomatous Univalves, 244, 303.
Holothurians, 122.
Holtcnia, 272.
Homacant tuts, 192.
Homalonotus, 126, 146 ; armatus, 147.
Homo diluvii testis, 324.
Honeycomb Corals, 144.
Hoofed Quadrupeds, 310.
Hudson River Group, 96.
Human implements associated with

bones of extinct Mammals, 377,

378.

Huronian Period, 75, 76; rocks of, 75.
Hysena crocuta, 342 ; spelsea, 374 ; Hip-

parionum, 342.

Hysenodon, 315.
Hyalea D'Orbir/nyana, 323.
Hybodus, 2 0, 249, 283.
Hydractinia, 273.
Hydroid Z9Ophytes, 104, 273.
Hymenocaris vermicauda, 84, 85.
Hymenophyllites, 167.
Hyme.noptera, 322.
Hyopotamus, 313.
Hyperodapedon, 224.
Hypsiprymnopsis, 230.
Hystrix primigenius, 333.

Ichthyocrinus leevis, 125.

IcMhyornis, 290, 291 ; dispar, 290, 291.

Ichthyosaurus, 249, 250, 285; communis,

249.

Ictitherium, 333.
Iguana, 286.

Iguanodon, 2C6, 287; Mantelli, 286.
Ilfracombe Group, 136.
Illsenus, 110, 126.
Imperfection of the palseontologi-

cal record, 52, 53.
Inferior Oolite, 234, 236.
Infusorial Earth, 35.
Inocerarmis, 277 ; sitlcatus, 278.
Insectivora'ot the Eocene, 316; of the

Miocene, 354.
Insects of the Devonian, 147; of the

Carboniferous, 186; of the Jurassic,

240; of the Miocene, 322, 323.
Irish Elk, 360.
Ischadites, 100, 120.
Isopod Crustaceans, 84.

Jackson Beds, 299.

Jurassic period, 232; rocks of, 333;
life of, 236, 263.

422

INDEX.

Jfaidacarpum, 237.

Kainozoic period, 45, 294-296.

Kangaroo, 362.

Kelloway Rock, 234.

Kent's Cavern, deposits in, 356.

Keuper, 209, 211.

Kimmeridee Clay, 234, 239.

King-crabs, 84, 126, 1/7, 182.

Koninckia, 219.

Kossen Beds, 210, 211.

Labyrinthodon Jcegeri, 223

Labyrinthodontia, 194; of the Carbon-
iferous, 19:M95; of the Permian,
204; of the Trias, 221-223.

Lace-corals, 110, 127, 148, 186, 202, 216.

Lacertilia, 206; of the Permian, 205,
206; of the Trias, 223, 224; of the
Jurassic, 259; of the Cretaceous,
288.

Lxlaps, 287.

Lamellibranchiata, of the Cambrian,
89; of the Lower Silurian, 112; of
the Upper Silurian, 130; of the De-
vonian, 150 ; of the Carboniferous,
190; of the Permian. 202; of the
Trias, 216; of the Jurassic, 242-244;
of the Cretaceous, 276-278; of the
Eocene, 302.

Lamna, 283, 323.

Lamp-shells (see Brachiopoda) .

Land-tortoises, 324.

Lauracete, 320.

Laurentiau period, 65 ; rocks of, 65,
66; Lower Laurentiau, 60; Upper
Laurentian, 66; areas occupiedby
Laureutian rocks,66; limestones of,
66, 67 ; iron-ores of, 68 ; phosphate
of lime of, 68; graphite of, 68; life
of, 67-75.

Leaf- beds of the Isle of Mull, 316.

Leda, 302; truncata, 351.

Leguminosites Marcouanus, 271.

Lemming, 358, 359.

Lepadidx, 275.

Lepadncrimw Gebhardi, 107.

Leperditia, 109; canadensis 108.

Lepidaster, 122.

Lepidechinus, 181.

Lepidesthes, 181.

Lepidodendroids, 168, 171, 212.

Lepidodendron, 120, 138, 168, 200; Stern-
bergi, 171.

Lepidoptera, 322.

Lepidosiren, 156.

Lepidosteus, 191.

Lepidostrobus, 170.

Lepidotus, 283.

Leptsena, 111, 112, 127, 241; Liassica,
242; sericea, 111.

Leptocoelia, 129 ; plano-convexa, 129.

Lias, 233, 234, 236.

Lichas, 110.

Licrophycus Ottawaensis, 98.

Ligmtic Formation of North Amer-
ica, 298, 304.

Lily-encrinite, 215, 216.

Lima, 242.

Lime, phosphate of, 31, 32.

Limestone, 24-29; varieties of, 29-31;
origin of, 22; microscopical struc-
ture of, 27; Crinoidal, 26; Forma-

miniferal, 25, 27; coralline, 26;
magnesian, 29; metamorphic, 27;
oolitic, 30-31; pisolitic, 30; bitumi-
nous, 37; Laurentian, 67.

Limnxa, 304; pyramidalis, 304.

Limulus, 84, 126, 127, 182.

Lingula, 88, 89, 111, 129, 149, 202; Cred-
neri, 202.

Lingula Flags, 78, 79, 89.

Lingulella, 88; Davisii, 88; ferrtir
ginea, 88.

Liriodendron, 270, 319; Meekii, 271.

Lithostrotion, 176 ; irregulare, 178.

Lituites, 132.

Lizards (see Lacertilia).

Llama, 368.

Llanberis Slates, 78.

Llandeilo rocks, 93, 95, 97.

Llandovery rocks, 94; Lower, 93; Up-
per, 117.

Lobsters, 183, 215, 240, 275.

Loess, 352.

London Clay, 297, 298.

Lougmynd rocks, 77-80, 88.

Lonsdaleia, 176.

Lophiodon, 327.

Lopkophytt'um, 176.

Lower Cambrian, 77-79; Chalk, 266;
Cretaceous, 264, 265 ; Devonian, 136;
Eocene, 297, "> 298; Greensand, 265,
266; Helderberg, 119, 120; Lauren-
tian rocks, 66; Ludlow rock, 117;
Miocene, 376; Old Red Sandstone,
136; Oolites, 234, 235; Silurian per-
iod, 91-116; rocks of, in Britain, 93-
95 , in North America, 94-97; life of,
98-116.

Loxonema, 190, 203, 219.

Ludlow rocks, 118, 119.

Lycopodiacese, 120, 139, 170.

Lynton Group, 136.

Lyrodesma, 112.

Macaques, 334, 343.

Machxracanthus major, 154, 157.

Machairodus, 227, 257, 333, 342,371;
cultridens, 343.

Maclurea, 112; crenulata, 113.

Macrocheilus, 190, 203, 219.

Macropetalichthys, 153 ; Sullivanti, 154.

Macrotherium giganteum, 326.

Macrurous Crustaceans, 183.

Mactra, 302.

Maestricht Chalk, 267, 288, 295.

Magnesian Limestone, 29; nature
and structure of, 30; of the Per-
mian series, 198, 200.

Magnolia, 270, 300, 320.

Mammalia, of the Trias, 230, 231 ; of
the Jurassic, 261, 262 ; of the Eocene,
309 314 ; of the Miocene, 324-334 ; of
the Pliocene, 339-343 ;Post-Pliocene,
361-379.

Mammoth, 352, 354, 358, 370-372.

Man, remains of, in Post-Piiocene
deposits, 354,357.

Manatee, 309.

Mantellia, 237 ; meqalophylla, 237.

Maple, 300, 320, 321.

Marble, 29; encrinital, 25; statuary,
28.

Marcellus Shales, 137.

INDEX.

423

Mariacrinus, 125.

Marmots, 334.

Marsupials, 809; of the Trias, 230; of

the Jurassic, 261,262 ; of the Eocene,

309; of the Miocene, 32(5; of the

Post- Pliocene, 361, 362.
Marsupiocrinuis, 124.
Marsupites, 274.
Mastodon, 331, 333, 334; Americanus,

angustidenv, 333; Arvencnsis, 341;

longirostris, 333; Ohioticus, 370; Siva-

lerutot 332.

Medina Sandstone, 118.
Mcgalichthys, 192.
Me'galodon, 150.

Megalomus, 130. ,

Me'galonyx, 365.
Mcgalosaurus, 2">6, 287.
Megatherium, 363, 364; Cuvieri, 363.
Melania, 304.
Melonites, 182.
Menevian Group, 77-79.
Menobranchits, 193.
Mcristclla 130; cylindrica, 129; iwter-

media, 129; navijormis, 129.
Mesopithccus, 334.
Mesozoic Period, 45.
Micheltnia, 145.
Micraster, 275.

Microlestes, 230 ; antiquus, 229.
Middle Devonian, 136; Eocene, 296,

298, 299; Oolites, 234 ; Silurian, 92.
Miliolite Limestone, 300.
3fi»fpo?Y?,237.
Millstone Grit, 162, 164.
Miocene period, 316; rocks of, in

Britain, 316; in France, 317: in

Belgium, 317; in Switzerland, 317;

in Austria, 317; in Germany, 318;

in Italy, 318 ; in India, 318 ; in North

America, 318; life of, 319-334.
Mitre-shells, 280, 303.
Mitra, 280, 803.

Moas of New Zealand, 359-361.
Modiolopsis, 111 ; Solvensis, 88.
Molasse, 317.
Mole, 334, 349.
Monkeys, 316, 343,
Monocotyledonous plants, 271.
Monograptus, 101, 121 ; priodon, 121.
Monotis, 217.

Monte Bolca, fishes of, 305.
Montlivaltia, 215.
Mosasauroids, 287, 288.
Mosasaurus, 287 ; Camperi, 287 ; prin-

ceps, 288.

Mountain Limestone, 161, 164.
Mud-fishes, 156, 221.
Mud-turtles, 289.
Mull, Miocene strata of, 316.
Murc.hisonia, 112, 131, 203, 219 ; gracilis,

112.

Murex, 244, 303.
Muschelkalk. 208, 209, 211.
Musk-deer, 328.
Musk-ox, 357, 358, 370.
Musk-sheep, 370.
Myliobntis, Edwardsii, 306.
Mylodon, 365 ; robuntus, 365.
Jfi/ophoria, 216; Uneata, 216.
Myriapoda of the Coal, 184, 185.

Nassa, 303.

Natatores, 807.

Natica, 279, 303.

Nautilus, 113-116, 132, 151, 190, 204, 244,

280, 304; Danicus, 280; pompilius. 244.
Neanderthal skull, 378.
Neocomian series, 264, 268.
Neolimulus, 127.

Nerinxa, 244, 279 ; Goodhallii. 244.
Nerita, 303.
Neuropteria, 322.
Neuropteris, 138, 167, 200.
Newer Pliocene, 335, 336.
New Red Sandstone, 197, 208.
Newts, 193, 204, 223.
Niagara Limestone, 118.
Nipadites, 300: ellipticus, 300.
Nseggerathia, 201.
Norwich Crag, 336.
Nothosaurus, 225 ; mirabilis, 225.
Notidanus, 249.
Numenius gypKorum, 307.
Nummulina, 176, 300; Itevigata; 301;

pristina, 176.
Nummulitic Limestone, 25, 297, 301.

Oak, 270, 321.

Obolella, 88 ; sagittalis, 88.

Odd-toed Ungulates, 310, 326, 340, 367.

Odontaspis, 283.

Odontopteris, 167 ; Schlotheimi, 168.

Odontopteryx, 308; toliapicus, 308.

Odontornithes, 290.

Ogygi'a, 110 ; Buchii, 108.

Older Pliocene, 335, 336.

Oldhamia, 81; antiqua. 82; slates of
Ireland, 79, 80.

Old Red Sandstone, 135; origin of
name, 135; of Scotland. 136; rela-
tions of, to Devonian, 135, 136, 157.

Olenus, 109 ; micrurus, 88.

Oligocene, 316.

Oligoporus, 182.

Olive-shells, 303.

Omphyma, 121.

Onchus, 132; tenuistriatus, 132.

Oneida Conglomerate, 118.

Onychodus, 156 ; sigmoides, 154.

Oolitic limestone, structure of, 80;
mode of formation of, 30.

Oolitic rocks (see Jurassic).

Ooze Atlantic, 23, 34.

Ophidia, 260; of the Eocene, 306.

Ophiuridea, of the Lower Silurian,
106 ; of the Upper Silurian, 122; of
the Carboniferous, 180; of the
Trias, 215 ; of the Jurassic, 246.

Opossum, 309, 326.

Orbitoides, 301.

Oriskany Sandstone, 137.

Ormoxylon, 140.

Orohippus, 312.

Orthis, 89, 111, 127, 149, 188, 111; bifor-
ata, 110 ; Davidsoni, 129 ; elegantula,
129; flabellulum, 110; Hicksii, 88;
lenticularis, 88; plicatella, 111: re-
supinata,l89 ; subquadrata, 110 ; tes^w-
dinaria, 111.

Orthoceras 89, 114, 115, 132, 151, 190, 114 ;
crebriseptnm, 114.

Orthonota, 112.

Orthoptera, 185, 322.

424

INDEX.

Osmeroides, 284 ; MantcUi, 284.

Osmerus, 285.

Osteolepis, 156.

Ostracode, Crustaceans of the Cam-
brian, 84; of the Lower Silurian,
109; of the Upper Silurian, 125; of
the Devonian, 146; of the Carboni-
ferous, 183; of the Permian, 202; of
the Trias, 215; of the Jurassic, 240;
of the Cretaceous, 275.

Ostrea acuminata, 242; Couloni, 111;
deltoidea, 242 ; distorta, 242 ; expansa,
gregarea, 242 ; Marshii, 242, 243.

Otodus, 305 ; obliquus, 306.

Otozamites, 234.

Otozoum, 211.

Oudenodon, 226 ; Bainii, 227.

Ovibos moschatus, 370.

Oxford Clay, 234, 236.

Oxyrhina, 323 ; xiphodon, 324.

Oysters, 242, 243, 277.

Pachyphyllum, 176.

Palxarca, 112.

Palxaster, 123; Kuthveni, 123.

Palasterina, 122 ; primceva, 123.

Palxchinus, 122, 182 ; elliptic™, 181.

Palxocaris, 184, ft/pws, 184.

Palxocoma, 122 ; Colvini, 123.

Palxocoryne, 176.

Palxolithic man, remains of, 377-379.

Palxomanon, 120.

Palxoniscus, 192, 204.

Palxontina Oolitica, 241.

Palseontological evidence as to Evo-

lution, 61, 386-388.
Palaeontological record, imperfec-

tion of the, 51, 52.
Palaeontology, definition of, 10.
Palxonyctis, 315.
Palseophis, 306: toliapicus, 306; <y-

Palxoreas, 329.

Palxosaurus, 206, 225; platyodon, 225.

Palxosiren Beinerti, 204.

Palseotherium, 3 0 ; magnum, 311.

Palxoxylon, 173.

Palaeozoic period, 45.

Palms, 237, 271, 300, 319, 320.

Paludina, 267, 304.

Pandaneoe, 237.

Pandanus, 270.

Paradoxides, 86, 87, 109; Bohemicus, 86.

Parasmilia, 274.

Parkeria, 272.

Pear Encrinite, 238.

Pearly Nautilus, 58, 112, 113, 244.

Peccaries, 328.

Pecopteris, 138, 167, 200.

Pecten Grcenlandicus, 351; Islandicus,

351 ; Valoniensis, 216, 217, 209.
Penarth Beds, 209.
Pennatulidx, 302.
Pentacrinus, 238; caput-medusse, 238;

fasciculosus, 239.
Pentamerus, 128, 128; galeatus, 129;

Knightii, 130.

Pentremites, (see Blastoidea).
Pentremites conoidcus, 180 ; pyriformis,

180.

Perching Birds, 307.
Percida, 284.

Periechocrinus, 125.

Perissodactyle Ungulates, 310, 326,339.

Permian period, 196-207; rocks of, in
Britain, 198; in North America,
199; life of, 200-312.

Persistent types of life, 59, 386.

Petalodus. 192.

Piaster, 122.

Petroleum, origin of, 37.

Pezophaps, 361.

Phacops, 110, 126, 146; Doumingice, 126;
granulatus, 147; tevis, 147 ; latifrons,
147, 146 ; longicaudatm, 126 ; rana, 146.

Phcenopora ertsiformis, 128.

Phalangers.362.

Phanerogams, 167.

Phaneropleuron, 156.

Phascolotherium, 261, 261.

Pheronema, 272.

Phillipsastrsea, 144.

Phillipsia, 183; seminifera, 184.

Pholadomya, 242.

Phormosoma, 181.

Phorus, 279.

Phosphate of lime, concretions of,
31; disseminated in rocks, 31; ori-
gin of, 32.

Phyllograptus, 104 ; ft/pits, 103.

Phyllopoda, of the Cambrian, 84; of
the Lower Silurian, 109; of the Up-
per Silurian, 125; of the Devonian,
148; of the Carboniferous, 183; of
the Permian, 201 ; of the Trias, 216.

Phylloporn, 216.

Physa, 304 ; columnaris, 304.

Pigs, 313, 328, 340, 367.

Pilton Group, 136.

Pinites, 173.

Pisces (see Fishes).

Pisolite, 30.

Pisolitic Limestone of France, 265,
295.

Placodus, 226 ; fi^os, 226.

Placoid Fishes, 152; of the Upper
Silurian, 132, 133; of the Devonian,
155-156; of the Carboniferous. 191;
of the Permian, 204; of the Trias,
220; of the Jurassic, 249; of the
Cretaceous, 283; of the Eocene, 305 ;
of the Miocene, 323.

Plagiaulax, 261.

Planolites, 125; vulgaris, 125.

Planorbis, 304.

Plants, of the Cambrian, 80, 81; of
Lower Silurian, 98, 99; of the Up-
per Silurian, 120; of the Devonian,
138-141 ; of the Carboniferous, 167-
174; of the Permian, 200; of the
Trias, 212, 213; of the Jurassic, 236,
237; of the Cretaceous, 269, 271; of
the Eocene, 299, 300; of the Miocene,
319-322.

Plasmopora, 121.

Platanus, 270, 320 ; aceroides, 320.

Platephemera antiqua, 147.

Platiiceras, 130, 151; dumosum, 151;
multisinuatum, 131; ventricosum, 131.

Plaiycrinus, 124, 178; tricontadactylus,
179

Platyostoma, 131; Niagarense, 131.

Platyrhine Monkeys, 375.

Platyschisma helicites, 131.

INDEX.

425

Platysomus, 204 ; gibbosus, 203.

Platystoma, 219.

Pleistocene period, 346; climate of ,
375.

Plesiosaurus, 225, 251-255, 285 ; ctoMcto-
deirus, 251.

Pleurocystites squamosus, 107.

Pleurotoma, 303.

Pleurotomaria, 112, 131, 190, 203, 244, 279.

Plicatula, 219.

Pliocene period, 335; rocks of, in
Britain, 336; in Belgium. 337; in
Italy, 337; in North America, 337;
life of, 338-343.

Pliopithecus. 334; antiques, 334.

Pliosaurus, 252.

Podocarya, 237 .

Podozamites, 213; lanceolalus, 214.

Polir-schiefer, 34.

Polycystina, 34; of Barbadoes-earth,
34.

Polypora, 148, 186 ; dendroides, 187.

Polypterus, 155, 191.

Polystvmella, 322.

Polytremacis, 274.

Polyzoa, of the Cambrian, 82, 90; of
the Lower Silurian, 110; of the
Upper Silurian, 127; of the De-
vonian. 147, 148; of the Carbonifer-
ous,186', 187 ; of the Permian, 202 ; of
the Trias, 215; of the Cretaceous,
275 ; of the Miocene, 323.

Populus, 272.

Porcellia, 190.

Porcupines, 333.

Portage Group, 137.

Port-Jackson Shark, 156, 192,249.

Portland beds, 234, 236.

Post-Glacial deposits, 348, 351.

Post-Pliocene period, 346.

Post-Tertiary period, 296.

Poteriocrinus, 179

Potsdam Sandstone, 79.

Pre-Glacial deposits, 848.

Prestwichia, 182 ; rotundata, 183.

Primitia,\09 ; strangulata, 108.

Primordial Trilobites, 85.

Primordial zone, 79.

Proboscidea, of the Miocene, 331, 334 ;
of the Pliocene, 341, 342; of the
Post-Pliocene, 370. 373.

Producta, 150, 188, 202; horrida, 202;
longispina, 189; semireticulata, 189.

Productella, 150, 188.

Productidse, 149, 216.

Proetus, 126.

Prong-buck, 330.

Protaster, 122 ; Sedgwickii, 123.

Proteaceas, 270, 320.

Proteus, 193

Protichni'es, 87.

Protocystites, 82.

Protornis Glarisiensis, 307.

Protorosaurus, 2 6 ; Speneri, 205.

Protospongia, 82 ; fenestrata, 88.

Prototaxites, 120, 140; Logani, 141.

Psammobia, 302.

Psammodus, 192.

Psaronius, 138, 167.

Pseudocrinus bifasciatus, 107.

Psilophyton, 120, 189, 140; princeps. 140.

Pteranodon, 254, 285; longiceps, 285.

Pteraspis, 132, 154 ; Banksii, 132.
Plerichthys, 154 ; cor nut as, i56.
Pterincea, 130 ; subfa/cata, 130.
Pteroceras, 244, 280.

Pterodactylus, 252, 265 ; crassirostris, 253.
Pternphyllum. 213, 237 ; Jcegeri, 214.
Pteropoda, of the Cambrian, 89 ; of the

Lower Silurian, 112; of the Upper

Silurian, 131 ; of the Devonian, 151 ;

of the Carboniferous, 189; of the

Permian, 2'>3; of the Jurassic, 244.
Pterosauria, 252; of the Jurassic, 252-

255; of the Cretaceous, 285.
Pterygotus Anglicus, 126, 127.
Ptilodictya, 110, 127; acwta. 109;/aZa'-

/orww's 109; raripora, 128; Schafferi,

109.

Ptychoceras, 281 ; Ewericianum, 282.
Ptychodus, 283.
Pupa vetueta, 190.

Purbeck Beds, 234; Mammals of, 262.
Purpuroidea, 244.
Pycnodus, 283.
Pyrula, 303.

Quadrumana, of the Eocene, 316; of
the Miocene, 334; of the Plio-
cene, 343 : of the Post- Pliocene, 375.

Quadrupeds (see Mammalia).

Quaternary period, 346.

Quebec Group, 96, 97, 101.

Qutrcus, 270.

Rabbits, 333.

JZana, 324.

Raptores, 308.

Rasores. 307.

Recent period, 296, 346.

Receptaculites, 99.

Red clays, origin of, 36.

Red Coral, 322.

Red Crag, 335.

Red Deer, 349, 368.

Reindeer, 367, 358, 368, 369.

Remopleurides, 120.

Reptiles, 204; of the Permian, 204-
2u7; of the Trias, 223-227; of the
Jurassic, 249-258; of the Cretace-
ous, 285-290; of the Eocene, 306, 307.

Retepora, 110, 127, 148, 186, 202, 216;
Ehrenbergi, 202 ; Phittipsi, 148.

Retiolites, 121.

Retzia, 130.

Rhaetic Beds, 209-211.

Phamphorhynchus, 255 ; Bucklandi, 255.

Rhinoceridse, 326.

Rhinoceros Etruscus, 339,340, 349, 367;
leptorhinus, 339 ; megarhinus, 339-340,
349, 367 ; tichorhinus, 367.

Rhinopora verrucoaa, 128.

Rhizodus, 192.

Rhombus minimus, 305.

Rhyncholites, 246.

RhynchoneUa, 112, 130, 149, 188, 241 , 276,
302 ; cuneata, 129 ; neplecta, 129 ; pfe«-
rodon, 189; varians, 242.

Rhi/nchosaurus, 224; articeps, 224.

Rice-shells, 303.

Richmond Earth, 35, 818.

Ringed Worms (see Annelida).

River-gravels, high-level and low-
level, 352-353.

426

INDEX.

Robulina, 322.

Rocks, definition of, 15; divisions of,
15, 16; igneous, 15; aqueous, 17-19;
mechanically-formed, 19-21 ; chem-
ically - formed, 21 ; organically-
formed, 21-38; arenaceous, 21; argil-
laceous, 21; calcareous. 21-33; sili-
ceous, 21,33-35.

Rodentia of the Eocene, 316; of the
Miocene, 333; of the Post-Pliocene,
375.

Roebuck. 349, 368.

Hostellana, 214, 303.

Jtotalia, 23, 99, 175, 272; Boueana, 272.

Rugose Corals, 105; of the Lower
Silurian, 106; of the Upper Sil-
urian, 121; of the Devonian, 144;
of the Carboniferous, 176-177 ; of the
Permian, 251; of the Upper Green-
sand, 274.

Rupelian Clay, 318.

Sabal major, 319.
Sabre-toothed Tiger, 333, 343.
Saccammina, 175.
Saccosoma, 239.
Salamanders, 193, 324.
Salina, Group, 119.

Salmonidce, 284.

Sao hirsuta, 85.

Sassafras cretacea, 271.

Sauropterygia, 225.

Scalaria, 279, 303 ; Orcelandica, 351.

Scaphites, 281, 282; cequalis, 282.

Schizodus, 203, 217.

Schoharie Grit, 137, 139.

Scolecoderma, 83.

Scoliostoma, 219.

Scolithus, 83 ; Canadensis, 108.

Scorpions of the Coal-measures, 185.

Scorpion-shells, 280.

Screw-pines, 237.

Scutetta, 822 ; subrotunda, 323.

Sea-cows (see Sirenia).

Sea-lilies (see Crinoidea).

Sea-lizards (see Enaliosaurians).

Seals, 333.

Sea-mats and Sea-mosses (see Poly-

zoa).

Sea-shrubs (see Gorgonidse).
Sea-urchins (see Echinoidea).
Sea-weeds, 80, 81, 84, 98, 138, 167, 269.
Secondary period, 45.
Sedimentary rocks, 15.
Semnopithecus, 334, 343.
Septaria, 32.
Sequoia, 316,320 ; Couttfix, 320 ; gigantea,

320; Langsdorffi,3'2Q.
Scrolls, 84.

Serpents (see Ophidia).
Serpulites, 125.

Sewalik Hills (see SiwAlik Hills).
Sheep, 369.
Shell-sands, 20.
SigUlaria, 170, 172; Orceseri, 172.
Sigillarioids. 138, .70, 173,200.
Silicates, in filtration of the shells

of Foraminifera by, 35, 74.
Siliceous rocks, 21, 33.
Siliceous Sponges, 273.

Silicification, 13, 14.

Silurian period (see Lower Silurian
and Upper Silurian), 91-116, 117-134.

Simosaurus, 224 ; (.laillardoti, 224.

Siphonia, 272;ficw>, 273.

Siphonostomatous Univalves, 241,
280, 303.

Siphonotreta, 112.

Sirenia, 309, 331 ; of the Eocene, 309 ; of
the Miocene, 326.

Siren lacertina, 204.

Sivatherium, 329 ; giganteum, 329.

Siwalik Hills, Miocene strata of, 318.

Skiddaw Slates, 102.

Sloths, 326, 363, 364.

Smilax, 320.

Smithia, 176.

Snakes (see Ophidia).

Soft Tortoises, 306.

Solarium, 279.

Solenhofen Slates, 235.

Solitaire, 359, 361.

Spalacotfierium, 262.

Spatangus, 322.

Sphcerospongia, 141.

Sphagodus, 132.

Sphenodon, 224.

Sphenopteris, 138, 167, 200.

Spiders of the Coal-measures, 185.

Spider-shells, 244.

Spindle-shells, 244.

Spirifera,I28, 149, 188, 202, 241; crispa,
129; disjuncta, 149; hysterica, 128;
mucronata, 149 ; Niagarensis, 1 29 ; ros-
trata, 242 ; sculptilis, 149 ; trigoncUis,
189.

Spiriferidse, 149.

Spirophyton cauda-Oatti, 137, 167.

Spirorbis, 125, 145, 182; Arkonensis, 146;
Carbonarius, 182; laxus, 146; Lewisii.
12- ; omphalodes, 146; swrmfyfero, 146.

Spirulirostra, 323.

Spondylus, 277 ; spinosus, 278.

Sponges, of the Cambrian, 82 ; of the
Lower Silurian, 99 ; of the Upper
Silurian, 120; of the Devonian,
141; of the Carboniferous, 175; of
the Permian, 201 ; of the Trias, 214;
of the Jurassic, 237; of the Cre-
taceous, 272, 273.

Spongilla, 201.

Spongillopsis, 201.

Spongophyllum, 176.

Spore-cases, of Cryptogams in the
Ludlow rocks, 120; in the Coal, 165.

Squirrels, 334.

Stagonolepis, 224.

Staircase-shells, 279.

Stalactite, 22.

Stalagmite, 22.

Star-corals, 238.

Star-fishes, 106, 122. 216.

St. Cassian Beds. 209, 210.

Stephanophyllia, 274.

Stereognathus, 261, 262.

Stigmaria. 173;flcoides, 173.

Stouesfield Slate, 234; Mammals of,
261.

Strata, contemporaneity of, 45.

Stratified rocks, 16-19.

Streptelasma, 106.

Streptorhynchus, 202.

INDEX.

427

Stroinntopora, 99,100, 120, 141; rugosa, 99;

(uberculata, 142.
Stroiubodes, 121; pentagonus, 105.

trombus, 280.
Strophalosia, 202.
Mrophodus, 262.
Strophomena, IIP, 111, 127, 149, 188 ; o#er-

nato, 111; ddtoidea, 110; filitexta, 111;

rhomboidalis, 150, }5'2\subplana, 129.
Sub-Appennine Beds, 337.
Sub-Carboniferous rocks, 161, 164.
Succession of life upon the globe,

381-388.

S-uda, 313, 328. 340.
Sulphate of lime, 23.
Sus Erymanthius, 328; scrofa, 367.
Synastrcsa, 215.
Synhelia Sharpeana, 274.
Synocladia, 202; virgulacea, 202.
Syringopora, 121, 1/4; ramulosa, 178.

Tabulate Corals, 106; of the Lower
Silurian, 106; of the Upper Silu-
rian, 121; of the Devonian, 141; of
the Carboniferous, 176; of the Per-
mian, 201.

Talpa Europvea, 349.

Tapiridx, 310.

Tapirs, 310.

Tapirus Arvernensis, 3 10.

Taxocrimis tuber culatus, 124.

Taxodium, 270, 319, 321.

Teleosaurus, 260.

Teleostean Fishes, 152; of the Cre-
taceous, 283.

Telerpeton Elginense, 224.

Tettina proximo, 351.

Tentaculites, 131, 151; ornatus, 131.

Terebra, 303.

Terebratella, 276; Astieriana, 276.

Terebratula, 188, 241; digona, 242: efon-
#ota, 202; hastata 186; quadrifida, 242;
sphoRroidalis, '242.

Terebratulina, 276; caput-serpentis, 276;
sonata, 276.

Termites, 322.

Terrapins, 289, 306.

Tertiary period, 45, 294-296.

Tertiary rocks, classification of, 295-
296.

Testudinidx, 324.

Tetrabranchiate Cephalopoda, 114;
of the Cambrian, 89; of the Lower
Silurian. 113-116; of the Upper Silu-
rian, 132; of the Devonian, 151 ; of
the Carboniferous, 189, 190; of the
Permian, 203; of the Trias, 217; of
the Jurassic, 244, 246; of the Cre-
taceous, 280-283; of the Eocene,
304; of the Miocene, 322.

Textularia, 23, 272, 322; Meyeriana, 322.

Thanet Sands 297, 298.

TVca, 89. 112,131.

Theca Damdii, 88.

Thecidium, 219.

Thecodont Reptiles, 224.

Thecodontosaurus, 206, 224; antiquus,
225.

Thecosmilia annulai is, 238.

Thelodus, 132.

Theriodont Reptiles, 206, 227.

Thylacoleo, 362.

Tile-stones, 118.

Titanotherium, 327.

Toothed Birds, 289-292.

Tortoises, 207, 306.

Tragoceras, 329.

Travertine, 22,

Tree-Ferns, of the Devonian, 138; of
the Coal-measures, 169.

Tremadoc Slates, 78-79.

Trematis, 112.

Trenton Limestone, 96, 97.

Triarthrus Beckii, 108.

Triassic period, 209; rocks of, in
Britain, 209; in Germany. 209; in
the Austrian Alps, 210; in North
America, 210; life of, 211-231.

Triconodon, 262.

Trigonia, 24 ', 262, 277.

Trigoniadif, 203, 217.

Trigonocarpum, 173 ; ovatum, 173.

Trilobites, H4-88; of the Cambrian,
86,88; of the Lower Silurian, 108,
109; of the Upper Silurian. 125, 126;
of the Devonian. 146,147; of the
Carboniferous, 183.

Trimerellidse, 129.

Trinucleus, 110 ; concentricus, 108.

Trionycidse, 306.

Triton, 803.

Trochocyathus, 274.

Trochonema, 131.

Trogontherium, 375 ; Cuvieri, 349, 375.

Trumpet-shells, 303.

Tulip-tree, 270, 319.

Turbinolia sulcata, 302.

Turbinolidx, 302.

Turrilites, 281, 282 ; catenulatus, 281.

Turritella, 279, 303.

Turtles, 207, 259, 281, 306.

Typhis tubifer, 803.

UUmania selaginoides, 201.

Unconformability of strata, 50.

Under-clay of coal, 165.

Ungulata, of the Eocene, 310-313: of
the Miocene, 326-330; of the Plio-
cene, 339-340 ; of the Post- Pliocene,
366-367.

Uniformity, doctrine of, 5-7.

Unio, 277.

Univalves (see Gasteropoda).

Upper Cambrian, 77-79; Chalk, 266;
Cretaceous, 264. 268; Devonian, 137;
Eocene, 296, 298; Greensand, 2ftO;
Helderberg, 1*7; Laurentian, 66;
Llandovery, 117; Ludlow rock, 117;
Miocene, 316; Oolites, 234; Silurian
period, 116; rocks of, in Britain,
117, 118; in North America, 118-120,
life of, 120-134.

Ursus arctos, 373; Arvernensis, 341; fe-
rox, 373; speloea, 3'<3.

Ursus, 349, 369.

\ ailey- gravels, high-level and iow-

level, 352-354.
Vanessa Pluso, 322.
Varanidtz, 206.
Vegetation (see Plants).
Vcntriculites, 272, 273: simplex, 273.
Venus's Flower-basket, 273.
Vermilia, 201.

428

INDEX.

Vespertilio Paris iensis, 315.
Vicksburg Beds, 299.
Vines, 316, 320, 321.
Vitreous Sponges, 272.
Vottzia, 213; heterophylla, 214.
Valuta, 279, 303; elongata, 279.
Volutes, 280, 303, 323.

IValchia, 200, 201; piniformis, 200.

Walrus, 333.

Wealden Beds, 264.

Wellingtonia, 320.

Wenlock Beds, 117, 119; Limestone,

117 ; Shale, 117.
Wentle-traps, 279.
Werfen Beds, 210, 211.
Whalebone Whales, 309, 326.
Whales, 309, 326.
Whelks, 244.
White Chalk, 266 ; structure of, 22, 23 :

origin of, 24, 271.
White Crag, 335.
White River Beds, 318.
Wild Boar, 367.

Williamsonia, 237.

Winged Lizards (see Pterosauria),

Winged Snails (ra; Pteropoda). '

Wing-shells, 280.

Wolf, 349, 374.

Wolverine, 374.

Wombats, 362.

Woolhope Limestone, 117.

Woolly Rhinoceros, 352, 354, 357, 367.

Woolwich and Reading Beds, 298.

Worm-burrows, 83, 84, 123.

Xanthidia, 141.
Xenoneura antiquorum, 147.
Xiphondon, 313.
Xylobius, 186 ; Sigillarise, 186.

Zamia spiralis, 213.

Zamiies, 213, 237, 321.

Zaphrentis, 106, r. 1, 144, 177; cornicula,

143; Stokesi, 105 ; vermicularis, 178.
Zeacrinus, 179.
Zechstein, 198.
Zeuglodon, 309, 326; cetoides, 310.

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