B 3 
 
 OF LIFE 
 
 OLOGICAL TIME. 
 
 W. DAWSON, LL.D. ERS 
 
TH] 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 PRESENTED BY 
 
 PROF. CHARLES A. KOFOID AND 
 MRS. PRUDENCE W. KOFOID 
 
 EARTH 
 SCIENCES 
 LIBRARY 
 
THE CHAIN OF LIFE 
 
 GEOLOGICAL TIME 
 
 A SKETCH OF THE ORIGIN AND SUCCESSION OF 
 ANIMALS AND PLANTS 
 
 BY 
 
 SIR J. WILLIAM DAWS ON 
 
 C.M.G., LL.D., F.R.S., F.G.S., ETC. 
 AUTHOR OF 
 
 "ACADIAN GEOLOGY," "THE STORY OF THE EARTH," "EGYPT AND SYRIA; THEIR 
 PHYSICAL FEATURES IN RELATION TO BIBLE HISTORY," ETC. 
 
 THIRD AND REVISED EDITION 
 
 WITH NUMEROUS ILLUSTRATIONS 
 
 THE RELIGIOUS TRACT SOCIETY, 
 
 56 PATERNOSTER Row; 65 ST. PAUL'S CHURCHYARD, 
 AND 164 PICCADILLY 
 
 1888 
 
 :. 
 
RICHARD CLAY AND SONS, 
 LONDON AND BUNGAV. 
 
EARTH 
 SCIENCES 
 LIBRARY 
 
 PREFACE. 
 
 QUESTIONS as to the origin and history of life are not at the 
 present time answered by mere philosophical speculation and 
 poetical imagining. Such solutions of these questions as 
 science can profess to have obtained are based on vast accu- 
 mulations of facts respecting the remains of animals and 
 plants preserved in the rocky beds of the earth's crust, which 
 have been successively accumulated in the course of its long 
 geological history. These facts undoubtedly afford the means 
 of attaining to very certain conclusions on many points relat- 
 ing to the history of life on the earth. But, on the other hand, 
 they have furnished the material for hypotheses which, though 
 confidently affirmed to be indisputable, have no real founda- 
 tion in nature, and are indirectly subversive of some of the 
 most sacred beliefs of mankind. 
 
 In these circumstances it is most desirable that those who 
 are not specialists in such matters should be in a position 
 to judge for themselves; and it does not appear impossible 
 in the actual state of knowledge, to present, in terms intel- 
 ligible to the general reader, such a view of the ascertained 
 sequence of the forms of life as may serve at once to give 
 
vi PREFACE, 
 
 exalted and elevating views of the great plan of creation, 
 and to prevent the deceptions of pseudo-scientists from doing 
 their evil work. Difficulties, no doubt, attend the attempt. 
 They arise from the number and variety of the facts, from the 
 uncertainties attending many important points, from the new 
 views constantly opening up in the progress of discovery, and 
 from the difficulty of presenting in an intelligible form the 
 preliminary data in biology and geology necessary for the 
 understanding of the questions in hand. In order, as far as 
 possible, to obviate these difficulties, the plan adopted in this 
 work has been to note the first known appearance of each 
 leading type of life, and to follow its progress down to the 
 present time or until it became extinct. This method is at 
 least natural and historical, and has commended itself to the 
 writer as giving a very clear comprehension of the actual state 
 of our knowledge, and as presenting some aspects of the 
 subject which may be novel and suggestive even to those who 
 have studied it most deeply. 
 
 In selecting examples and illustrations, the writer has en- 
 deavoured to avoid, as far as possible, those already familiar 
 to the general reader. He has carefully sought for the latest 
 facts, while rejecting as unproved many things that are con- 
 fidently asserted ; and has endeavoured to avoid all that is 
 irrelevant to the subject in hand, and to abstain from all 
 technical terms not absolutely essential. In a work at once 
 so wide in its scope, so popular in its character, and so limited 
 in its dimensions, a certain amount of hostile criticism on the 
 part of specialists is to be expected, some portion of it per- 
 haps just, other portions arising from narrow prejudices due 
 to limited lines of study. The writer is willing to receive 
 
PREFACE. vii 
 
 such comments with attention and gratitude, but he would 
 deprecate the misuse of them in the interest of those coteries 
 which are at present engaged in the effort to torture nature 
 into a confession of belief in the doctrines of a materialistic 
 or agnostic philosophy. 
 
 The title of the work was suggested by that of Gaudry's 
 recent attractive book, Les Enchainements du Monde animal. 
 It seemed well fitted to express the connection and succession 
 of forms of life, without implying their derivation from one 
 another, while it reminds us that nature is not a fortuitously 
 tangled skein, and that the links which connect man himself 
 with the lowest and oldest creatures bind him also to the 
 throne of the Eternal. 
 
 In the few years that have elapsed since the publication of 
 the first edition of this work, great additions have been made 
 to our knowledge of fossil animals and plants. Many new 
 species have been described, and many new facts have been 
 discovered, respecting species previously known. This rapid 
 progress of discovery has, however, invalidated few of the 
 statements made in the first edition, and has certainly estab- 
 lished nothing against the general laws of the succession of life 
 as stated in this work. 
 
 Perhaps the most interesting phase of recent discovery is the 
 tracing back of certain forms of life to earlier periods of the 
 earth's geological history. Some of the most recent facts of 
 this kind are the finding, by M. Charles Brongniart, of a fossil 
 insect, allied to the Blattae or cockroaches, in the Silurian of 
 Spain, that of true Scorpions in the Upper Silurian of Sweden 
 by Lindstrom, and in the Upper Silurian of Scotland by Peach, 
 who has also described fossil Millipedes from the Lower 
 
viii PREFACE. 
 
 Devonian. The tendency of such discoveries is to carry 
 farther back the origin of highly specialised forms of life, and 
 thus to 'render less probable their origin by any process of 
 gradual derivation. 
 
 Other discoveries serve to fill up blanks in our knowledge, 
 and thus to render the geological record less imperfect. Of 
 this kind is the close approximation now worked out in Western 
 America between the end of the reign of the great Mesozoic 
 reptiles and the beginning of that of the mammals of the 
 Tertiary a great and abrupt revolution, effected apparently by 
 a- coup de main. I have myself had opportunity to show that a 
 similarly sharp line separates that quaint old Mesozoic flora 
 of pines, cycads and ferns, which extends upward into the 
 Lower Cretaceous, from the rich and luxuriant assemblage of 
 broad-leaved trees of modern aspect, which takes its place in 
 the middle part of the same formation. 
 
 It is not too much to say that these and similar discoveries, 
 while they serve to bridge over gaps in the succession of 
 organic beings, do not favour the theory of slow modification 
 of types. They rather point to a law of rapid development of 
 new forms under special conditions as yet unknown to science, 
 and this accompanied with the extinction of older species. 
 Recent discoveries also present many remarkable instances of 
 the early introduction of highly specialised types, of higher 
 forms preceding those that are lower in the same class, and of 
 the persistence of certain types throughout geological time 
 without any important change. 
 
 J. W. D. 
 
 McGiLL COLLEGE. 
 
CONTENTS. 
 
 CHAP. PAGE 
 
 I. PRELIMINARY CONSIDERATIONS AS TO THE EXTENT AND 
 
 SOURCES OF OUR KNOWLEDGE i 
 
 II. THE BEGINNING OF LIFE ON THE EARTH 21 
 
 III. THE AGE OF INVERTEBRATES OF THE SEA 45 
 
 IV. THE ORIGIN OF PLANT LIFE ON THE LAND 89 
 
 V. THE APPEARANCE OF VERTEBRATE ANIMALS . . . . '. 117 
 
 VI. THE FIRST AIR-BREATHERS 137 
 
 VII. THE EMPIRE OF THE GREAT REPTILES 165 
 
 VIII. THE FIRST FORESTS OF MODERN TYPE 185 
 
 IX. THE REIGN OF MAMMALS 207 
 
 X. THE ADVENT OF MAN 233 
 
 XL REVIEW OF THE HISTORY OF LIFE 253 
 
LIST OF ILLUSTRATIONS. 
 
 FRONTISPIECE. Life in the Silurian Age .... To face Title. 
 
 FIG. PAGE 
 
 1. Bank of stream or coast, showing stratification ... 4 
 
 2. Section at Niagara Falls 4 
 
 3. Section obtained by boring, near Goderich, Ontario . . 5 
 
 4. Inclined beds, holding fossil plants 6 
 
 5. Ideal section of the Apalachian Mountains .... 7 
 
 6. Generalised section across England from Menai Straits to 
 
 the Valley of the Thames 9 
 
 7. Generalised section from the Laurentian of Canada to the 
 
 coal-field of Michigan 9 
 
 8. Unconformable superposition of Devonian Conglomerate on 
 
 Silurian slates, at St. Abb's Head, Berwickshire . . 10 
 
 9. Section of Trenton limestone, Montreal 14 
 
 10. Diagram showing different state of fossilisation of a cell of a 
 
 Tabulate Coral 15 
 
 11. Cast of erect tree (Sigillaria) in Sandstone 16 
 
 12. Protichnites septem-notattts . . . . . . . .17 
 
 I2a. Footprints of modem Limulus, or king-crab . . . .18 
 
 13. Current markings on shale, resembling a fossil plant . . 1 8 
 Frontispiece. Magnified and restored section of a portion of 
 
 Eozoon canadense .......... 20 
 
 14. Ideal section, showing the relations of the Laurentian and 
 
 Huronian ........... 24 
 
 15. Small weathered specimen of Eozoon 23 
 
 1 6. Nature-printed specimen of Eozoon slightly etched with acid 29 
 
 17. Magnified group of canals in supplemental skeleton of Eo- 
 
 zoon 31 
 
 18. Portion of Eozoon magnified 100 diameters . . . .31 
 
 19. Magnified portion of shell of Calcarina 32 
 
 20. Amceba, a fresh- water naked Rhizopod ; and Actinophrys, 
 
 a fresh-water Protozoon ........ 34 
 
 21. Nonionina t a modern marine Foraminifer .... 34 
 
LIST OF ILLUSTRATIONS. xi 
 
 FIG. PAGE 
 
 22. Stromatopora concenirica 35 
 
 23. Caunopora planulata 36 
 
 24. Archoeocyathus minganensis. A Primordial Protozoon . . 37 
 
 25. Receptaculites. Restored 38 
 
 26. Section of Loftusia Persica. An Eocene Foraminifer . . 39 
 
 27. Foraminiferal Rock Builders, in the Cretaceous and Eocene 41 
 Frontispiece. Paradoxides Regina (Matthew) .... 44 
 
 28. Group of Cambrian Animals 46 
 
 29. Portion of skeleton of Hexactinellid Sponge (Cceloptychium) 49 
 
 30. Protospongia fenestrata (Salter) 50 
 
 31. Astylospongia prczmorsa (Koemer) 5 1 
 
 32. Spicules of Lithistid Sponge (Trichospongia, Billings) . . 51 
 
 33. Gldhamia antiqua (Forbes) . . . . . . . 5 2 
 
 34. Dictyonema sociale. Enlarged 52 
 
 35. Dictyonema Websteri (Dn.) 53 
 
 36. Group of modern Hydroids allied to Graptolites ... 54 
 
 37. Silurian Graptolitidse 55 
 
 38. Central portion of Graptolite, with membrane, or float (Di- 
 
 ehograpsus octobrachiatus, Hall) 55 
 
 39. Ptilodiclya acuta (Hall). Bryozoan 55 
 
 390. Fenestella Lye Hi (Dn.). A Carboniferous Bryozoan . . 56 
 
 40. Chaetetes fibrosa. A Tabulate Coral with microscopic cells . 56 
 
 41. a, Stenopora exilis (Dn.). b, Chaetetes tumidus (Edwards 
 
 and Haine) 57 
 
 42. Living Anthozoan Coral (Astrcea) 58 
 
 43. Tabulate Corals (Halisites and Favosites] 59 
 
 44. Rugose Coral (Heliophyllum IJalli) 59 
 
 440. Zaphrentis prolifica (Billings) 60 
 
 45. Rugose Corals (Zaphrentis Minas, Dn., and Cyathophyllum 
 
 Billingsi, Dn.) 60 
 
 46. Modern Crinoid (Rhizocrinus Lofotensis) 6 1 
 
 47. Palaaster Niagarensis (Hall) 62 
 
 48. Palachinus ellipticus (McCoy) 62 
 
 49. Pleurocyslites squamosus . . -63 
 
 50. Heterocrinus simplex (Meek) 63 
 
 51. Body of Glyptocrinus 63 
 
 52. Extracrinus Briar eus ......... 64 
 
 53. Pentacrimis caput-mednsa 64 
 
 54. Lingula anatina 65 
 
 55. Cambrian and Silurian Lingulse 65 
 
 56. Terebratula s ace u IMS (Martin) 66 
 
 57. Brachiopods ; genus Orthis 66 
 
 58. Rhynchonella increbrescens (Hall) 66 
 
 59. Spirifer nnicronatus (Conrad) 67 
 
 59. Athyris subtilita (Hall) 67 
 
 60. Protfuctus cora (D'Orbigny) ........ 68 
 
 61. Group of Older Palaeozoic Lamellibranchs .... 69 
 
 62. Conularia planicstata (Dn.). A Carboniferous Pteropod . 70 
 
 63. Silurian Sea-snails 70 
 
xii LIST OF ILLUSTRATIONS. 
 
 FIG. PAGE 
 
 64. Squid (Loligo) 72 
 
 65. Pearly Nautilus (Nautilus pompilius} . . . . . .72 
 
 66. Orthoceras ............ 73 
 
 67. Gomphoceras 73 
 
 68. Lituites 73 
 
 69. Nautilus Avonensis (Dn.) 74 
 
 70. Goniatites crenistria (Philips) ....... 74 
 
 71. Ceratites nodosus (Schloth) 75 
 
 72. Ammonites Jason (Reinecke) 76 
 
 J2a. Suture of Ammonites componens (Meek) 76 
 
 73. Cretaceous Ammonitidae 77 
 
 74. Belemnite 78 
 
 74#. Belemnotetithis antiquus ......... 78 
 
 75. Cambrian Trilobites 79 
 
 76. Transverse section of Calymene. A Silurian Trilobite . . 80 
 760. Burrows of Trilobite and of modern King-crab . . .81 
 
 77. Silurian Trilobites 82 
 
 78. Devonian and Carboniferous Trilobites 83 
 
 79. Palaeozoic Ostracod Crustaceans 83 
 
 80. Pterygotus anglicus 84 
 
 81. Amphipeltis paradoxus (Salter) .85 
 
 82. Anthropalamon Hilliana (Dn.) . .... 85 
 Frontispiece. Cordaites, of the group of Dory-Cordaites . 88 
 
 83. Protannularia Harknesni (Nicholson) 91 
 
 84. American Lower Silurian Plants 92 
 
 86. Fragment of outer surface of Glyptodendron of Claypole . 93 
 
 87. Psilophyton princeps (Dn.) 95 
 
 88. Trunk of a Devonian Tree-fern ( Caulopteris Lockwoodi, Dn.) 97 
 
 89. Frond of ArckceopfeHs Jacksoni (Dn.) 98 
 
 90. Portion of a branch of Leptophleum rhombicum (Dn.) . . 98 
 
 91. Calamites radiatus (Brongniart) 99 
 
 92. A Devonian Taxine Conifer (Dadoxylon ottangondianum, Dn.) IOD 
 
 93. Group of Devonian fruity &c 101 
 
 94. Structures of the oldest-known Angiospermous Exogen (Sy- 
 
 ringe Jiy Ion mirabile, Dn.) . . . . . . . .102 
 
 95. Asterophyllites parvula (Dn.) and Sphenophyllum antiquum 
 
 (Dn.) 103 
 
 96. Calamites 104 
 
 97. Carboniferous Ferns 105 
 
 98. Carboniferous Tree-ferns 107 
 
 99. Lepidodendron cori-ugatum (Dn.) ....... 108 
 
 100. Sigillaricz of the Carboniferous 109 
 
 101. Trigonocarpum Hookeri (Dn. ) . . . . . . in 
 
 Frontispiece. Pteraspis. Restored 116 
 
 102. Siluro-Cambrian Conodonts .118 
 
 103. Lower Carboniferous Conodont 119 
 
 104. a, Head-shield of an Upper Silurian Fish (Cy at has pis}; b, Spine 
 
 of a Silurian Shark (Onchus tenui-striatus, Agass.) ; c, d, 
 
 Scales of Thecodus , 121 
 
LIST OF ILLUSTRATIONS. xiii 
 
 FIG. PAGE 
 
 105. Cephalaspis Da-wsoni (Lankester) 122 
 
 106. Devonian Placoganoid Fishes (Pterichthys cornutus, Cephal- 
 
 aspis Lyelli) 123 
 
 107. Devonian Lepidoganoid Fishes (Diplacanthus and Osteolepis) 124 
 
 108. Modern Dipnoi (Ceratodus Fosteri -. and Lepidosiren 
 
 annectus) , ....... 124 
 
 109. Anterior part of the palate of Dipterus ..... 125 
 no. Dental plate of Conchodus plicatus (Dn.) . . . . 126 
 
 111. Dental plate of Ceratodus Barrandii . . . . . . 126 
 
 112. Dental plate of Ceratodus serratus 127 
 
 113. Jaws of Dinichthys Hertzeri (Newbeiry) 127 
 
 114. Lower Jaw of Dinichthys Hertzeri 128 
 
 115. Jaws of ' Lepidosiren 128 
 
 1 16. A small Carboniferous Ganoid (Palaoniscus (Rhadinichthys) 
 
 Modulus, Dn.) 129 
 
 117. Teeth and Spines of Carboniferous Sharks .... 130 
 
 118. Teeth of Cretaceous Sharks (Otodus and Ptychodus} . . 131 
 
 119. Tooth of a Tertiary Shark (Carcharodon) 132 
 
 1 20. A Liassic Ganoid (Dapedius} 132 
 
 121. Cretaceous Fishes of the modern or Teleostian type (Beryx 
 
 Lerwesiensis and Portheus molossus, Cope) . . . . 133 
 
 122. Modern Ganoids (Polypterus and Lepidosteus} . . . .134 
 Frontispiece. A Microsaurian of the Carboniferous Period 
 
 (Hylonomus Lyellt) . . . f 136 
 
 123. Wings of Devonian Insects 140 
 
 124. Land-snail (Pupa vetusta, Dn.) 143 
 
 125. Land-snail (Zonites (Conulus] priscus, Carpenter) . . . 143 
 
 126. Millipedes (Xylobius sigillaria, Dn. ; Archiulus Xylobioides, 
 
 Scudder ; X. farctus, Scudder) 145 
 
 127. Wings of Cockroaches 146 
 
 128. Wing of May-fly (Haplophlebium Barnesii, Scudder) . . 147 
 
 129. A Jurassic Sphinx-moth (Sphinx Snelleri, Weyenburgh) . 148 
 
 130. An Eocene Butterfly (Prodryas persephone, Scudder) . . 149 
 
 131. Abdominal part of a Carboniferous Scorpion . . . .150 
 
 132. Carboniferous Scorpion (Eoscorpius carbonarius, Meek and 
 
 Worthen) 151 
 
 133. Footprints of one of the oldest known Batrachians, probably 
 
 a species of Dendrerpeton . 152 
 
 134. Archegosaurus Decheni 154 
 
 135. Ptyonius 154 
 
 136. A large Carboniferous Labyrinthodont (Baphetes planiceps, 
 
 Owen) , 155 
 
 137. Baphetes planiceps (Owen) 156 
 
 138. A lizard-like Amphibian (Hylonomus aciedentatus) . .157 
 
 139. Stelliosaums longicostatus (Fritsch) .158 
 
 140. Section showing the position of an erect Sigillaria, contain- 
 
 ing remains of land animals 1 60 
 
 1400. Section of base of erect Sigillaria, containing remains of 
 
 land animals . 161 
 
xiv LIST OF ILLUSTRATIONS. 
 
 Frontispiece. Inhabitants of the English Seas in the Age of 
 Reptiles 164 
 
 141. Arm of Proterosaurus Speneri 166 
 
 142. Skeleton of Ichthyosaurus 167 
 
 142^. Head of Pliosaurtis . . 168 
 
 142^. Paddle of Plesiosaurus Oxoniensis 168 
 
 143. Skeleton of Clidastes 170 
 
 144. An Anomodont Reptile of the Trias (Dicynodon lacerticeps, 
 
 Owen) 170 
 
 145. A Theriodont Reptile of the Trias (Lycosaurus} . . .170 
 
 146. Skeleton of Pterodochylus crassirostris 170 
 
 147. Restoration of Rhamphorhyncus Bucklandi . . . .171 
 
 148. A Jurassic bird (Archaopteryx macroura) 172 
 
 149. Jaw of a Cretaceous Toothed Bird (Ichthyornis dispar) . 173 
 
 150. Jaw of Bathygnathus borealis (Leidy) 174 
 
 151. Hadrosaurus Foulkii (Cope) 175 
 
 152. Jaws of Megalosaurus 176 
 
 153. Tooth of Megalosaurus 177 
 
 154. Compsognathus 179 
 
 Frontispiece. Lower Cretaceous Leaves 184 
 
 155. Sassafras cretaceum (Newberry) 190 
 
 156. Liriodendron pnmcevum (Newberry) . . . . . .191 
 
 157. Onoclea sensibilis \ .191 
 
 158. Davallia tenuifolia . .192 
 
 159. Eocene Leaves 194 
 
 160. An Ancient Clover (Trifolium palceogceum, Saporta) . . 195 
 
 161. An Eocene Maple (Acer sextiamts, Saporta) . . . .195 
 
 162. A European Magnolia of the Eocene (M. diance, Saporta) . 195 
 
 163. Flower and Leaf of Bombax sepultijlorum .... 196 
 
 164. Branch and Fruit of Sequoia Couttsice (Heer) .... 197 
 
 165. Cinnamomum Schetichzeri (Heer) 198 
 
 Frontispiece. Sivatherium giganteum ...... 206 
 
 1 66. Jaw of Dromatherium sylvestre (Emmons) .... 209 
 
 167. Myrmecobius Jasciatus ......... 209 
 
 1 68. Jaw and Molar of Phascolotherium Bucklandi . . .210 
 
 169. Jaw and Pre-molar of Plagiaulax Becklesii . . . .210 
 
 170. Restoration of Palceotherium magnum 21 1 
 
 171. Skull of a Lower Eocene Perissodactyl (Coryphodon Hamatus) 214 
 
 172. Fore-foot of Coryphodon 215 
 
 173. Skull of Upper Eocene Perissodactyl (Dinoceras mirabilis} . 216 
 
 174. Fore-foot of Dinoceras 217 
 
 175. Skull of Miocene Perissodactyl (Brontotherium ingens, Marsh) 217 
 
 176. Series of Equine feet 218 
 
 177. Skull of generalised Miocene Ruminant (Oreodon major) . 221 
 
 178. Lower Jaw of Megatherium 222 
 
 179. Ungual Phalanx and Claw-core of Megatherium . . . 222 
 
 1 80. Tooth of Eocene Whale (Zettglodon cetioides) .... 223 
 
 181. Mastodon ohioticus 225 
 
 182. Head of Dinotherium giganteum 226 
 
LIST OF ILLUSTRATIONS. xv 
 
 FIG. j-AGE 
 
 183. Wing of Eocene Bat ( Vesfertilio aquensis) . . . 226 
 
 184. Skull of a Cymetar-toothed Tiger (Machairodus cultridens) . 228 
 
 185. Lower Jaw of Diyopithecus Fontani 229 
 
 Frontispiece. Contemporaries of Post-Glacial Man . . 232 
 
 1 86. Klephas primigenius 241 
 
 187. Tooth of Elasmotheritim 242 
 
 188. Engis Skull 243 
 
 189. Outlines of Three Prehistoric European Skulls compared with 
 
 an American Skull 244 
 
 190. Flint Implement found in Kent's Cavern, Torquay . 245 
 
 191. Bone Harpoon (Palseocosmic) 246 
 
 192. Sketch of a Mammoth carved on a portion of a Tusk of the 
 
 same Animal 249 
 
TABULAR VIEW OF GEOLOGICAL PERIODS AND OF LIFE-EPOCHS. 
 
 GEOLOGICAL PERIODS. 
 
 ANIMAL LIFE. 
 
 VEGETABLE 
 LIFE. 
 
 [ ) Modern. 
 
 Age of Man 
 
 
 Quaternary. (Post-Glacial. 
 CAINOZOIC 
 
 and modern 
 Mammals. 
 
 Age of 
 
 or { /Pleistocene or 
 NEOZOIC. ] 1 Glacial. 
 Tertiary . . I Pliocene. 
 1 Miocene. 
 
 Age of Extinct 
 Mammals. 
 (Earliest 
 Placental 
 
 Angiosperms 
 and Palms. 
 
 k \Eocene. 
 
 Mammals.) 
 
 
 f i Upper, 
 
 
 
 Cretaceous . < Lower, or 
 
 
 
 (Neocomian. 
 
 
 
 
 Age of Reptiles 
 
 (Earliest 
 
 TW/zcwV f Oolite. 
 MES070IC. \s uf ' \Lias. 
 
 and Birds. 
 
 Modern Trees.) 
 Age of 
 
 \ T - ( Middle, or 
 ' Muschelkalk. 
 \ VLower. 
 
 (Earliest 
 Marsupial 
 Mammals.) 
 
 Cycads and 
 Pines. 
 
 Permian . . l M ' agn ^ L ; mes tone. 
 
 (Earliest 
 
 
 \ Lower. 
 
 true Reptiles.) 
 
 
 (Upper Coal-Formation. 
 
 
 
 Carboniferous 1 Coal-Formation _ 
 I Carboniferous Limestone. 
 
 
 
 VLower Coal-Formation. 
 
 
 
 (Upper. 
 PALEOZOIC. *>****> (j^f 
 
 Age of 
 A mphibians 
 and Fishes. 
 
 Age of 
 Acrogens and 
 Gymnosperms. 
 (Earliest 
 
 
 
 Land Plants.) 
 
 Silurian . . {L^' 
 
 
 Age of A Igte. 
 
 Siluro-Cam- | Upper 
 
 Age of 
 
 
 Ordovician. ' ower< 
 
 Mollusks, 
 Corals, and 
 
 
 TUpper. 
 Cambrian . < Middle. 
 VLower. 
 
 Crustaceans. 
 
 
 ^Z. 
 
 Age of 
 Protozoa. 
 (First animal 
 remains.) 
 
 Indicatiins of 
 Plants 
 notdeterminable. 
 
 vBojian. 
 
 
 
THE CHAIN OF LIFE. 
 
 CHAPTER I. 
 
 PRELIMINARY CONSIDERATIONS AS TO THE EXTENT AND 
 SOURCES OF OUR KNOWLEDGE. 
 
 IT is of the nature of true science to take nothing on trust or 
 on authority. Every fact must be established by accurate 
 observation, experiment, or calculation. Every law and prin- 
 ciple must rest on inductive argument. The apostolic motto, 
 " Prove all things, hold fast that which is good," is thoroughly 
 scientific. It is true that the mere reader of popular science 
 must often be content to take that on testimony which he 
 cannot personally verify ; but it is desirable that even the most 
 cursory reader should fully comprehend the modes in which 
 facts are ascertained and the reasons on which conclusions are 
 based. Failing this, he loses all the benefit of his reading in 
 so far as training is concerned, and cannot have full assurance 
 of that which he believes. When, therefore, we speak of life- 
 epochs, or of links in a chain of living beings, the question is 
 at once raised What evidence have we of the succession of 
 such epochs? This question, with some accessory points, 
 must engage our attention in the present chapter. 
 
 B 
 
2 THE CHAIN OF LIFE. 
 
 Geology as a practical science consists of three leading parts. 
 The first and most elementary of these is the study of the dif- 
 ferent kinds of rocks which enter into the composition of those 
 parts of the earth which are accessible to us, and which we are 
 in the habit of calling the crust of the earth. This is the sub- 
 ject of Lithology> which is based on the knowledge of minerals, 
 and has recently become a much more precise department of 
 science than heretofore, owing to the successful employment of 
 the microscope in the investigation of the minute structure and 
 composition of rocks. The second is the study of the arrange- 
 ment of the materials of the earth on the large scale, as beds, 
 veins, and irregular masses ; and inasmuch as the greater part 
 of the rocks known to us in the earth's crust are arranged in 
 beds or strata, this department may be named Stratigraphy. 
 A more general name sometimes employed is that of Petro- 
 graphy. The third division of geology relates to the remains 
 of animals and plants buried in the rocks of the earth, and 
 which have lived at the time when those rocks were in 
 process of formation. These fossil remains introduce us to 
 the history of life on the earth, and constitute the subject 
 of Paleontology. 
 
 It is plain that in considering what may be learned as to 
 epochs in the history of life we are chiefly concerned with the 
 last of these divisions. The second may also be important as 
 a means of determining the relative ages of the fossils. With 
 the first we have comparatively little to do. 
 
 Previous to observation and inquiry, we might suppose that 
 the kinds of animals and plants which now inhabit the earth 
 are those which have always peopled it ; but a very little study 
 of fossils suffices to convince us that vast numbers of creatures 
 once inhabitants of this world have become extinct, and can 
 be known to us only by their remains buried in the earth. 
 When we place this in connection with stratigraphical facts, 
 we further find that these extinct species have succeeded each 
 other at different times, so as to constitute successive dynasties 
 
PRELIMINARY CONSIDERATIONS. 3 
 
 of life. On the one hand, when we know the successive ages 
 of fossil forms, these become to us, like medals or coins to the 
 historian, evidences of periods in the earth's history. On the 
 other hand, we are obliged in the first instance to ascertain the 
 ages of the medals themselves by their position in the succes- 
 sive strata which have been accumulated on the surface. The 
 series of layers which explorers like Schliemann find on the 
 site of an ancient city, and which hold the works of successive 
 peoples who have inhabited the place, thus present on a small 
 scale a faithful picture of the succession of beds and of forms 
 of life on the great earth itself. 
 
 Our leading criterion for estimating the relative ages of rocks 
 is the superposition of their beds on each other. The beds of 
 sandstone, shale, limestone, and other rocks which constitute 
 the earth's crust have nearly all been deposited thereon by water, 
 and originally in attitudes approaching to horizontality. Hence 
 the bed that is the lower is the older of any two beds. Hence 
 also, when any cutting or section reveals to us the succession 
 of several beds, we know that fossil remains contained in the 
 lower beds must be of older date. 
 
 We can scarcely walk by the side of a stream which has 
 been cutting into its banks, or at the foot of a sea-cliff, or 
 through a road-cutting, without observing illustrations of this. 
 For instance, in the section represented in Fig. i, we see at 
 the surface the vegetable soil, below this layers of gravel and 
 sand, below this a bed of clay, and below this hard limestone. 
 Of these beds a is the newest, d the oldest ; and if, for 
 example, we should find some marine shells in d, some fresh- 
 water shells in c, bones of land animals and flint arrow- 
 heads in b, and fragments of modern pottery in a, we should 
 be able at once to assign their relative ages to these fossils, 
 and to form some idea of the succession of conditions and cf 
 life which had occurred in the locality. 
 
 On a somewhat larger scale, we have in Fig. 2 a section of 
 the beds cut through by the great Fall of Niagara. All of 
 
 B 2 
 
4 THE CHAIN OF LIFE. 
 
 these except that marked a are very ancient marine rocks, 
 holding fossil shells and corals, but now forming part of the 
 interior of a continent, and cut through by a fresh-water 
 river. 
 
 FIG. i. Bank of stream or coast, showing stratification. 
 
 a, Vegetable soil. t>, Gravel and sand, c, Clays, d, Limestone rock, slightly 
 inclined. 
 
 In deep mines and borings still more profound sections 
 may be laid open, as in Fig. 3, which represents the sequence 
 of beds ascertained by boring with the diamond drill in search 
 
 FIG. 2. Section at Niagara Falls, showing the 
 Fall. Thickness of beds 
 
 ta^cut through by the action of the 
 u725o feet. 
 
 a, Boulder clay and gravel Post-pliocene. 
 
 d, Clinton limestone j 
 
 e, Medina sandstone / 
 
 marine shells and 
 corals. 
 
 of rock salt near Goderich in Canada. Here we have a suc- 
 cession of 1,500 feet of beds, some of which must have been 
 formed under very peculiar and exceptional conditions. The 
 beds of rock salt and gypsum must have been formed by the 
 drying up of sea-water in limited basins. Those of Dolomite 
 
PRELIMINARY CONSIDERATIONS. 
 
 5 
 
 imply precipitation of carbonate of lime and magnesia in the 
 sea-bottom. The marls must have been formed largely by the 
 driftage of sand and clay, while some of the limestone was 
 
 78' 9" 
 
 278' 3" 
 
 276" of 
 
 I'o" 
 
 I 3 2'o" 
 
 Total 1,517 ft. 
 
 FIG. 3. Section obtained by boring with the diamond drill, near Goderich, Ontario, 
 Canada, in the Salina series of the Upper Silurian. From a memoir by Dr. Hunt 
 in the Report of the Geological Survey of Canada for 1876-7. 
 
 No. i, Clay, gravel, and boulders Post-pliocene. Nos. 2, 4, 7, 9, 13, Dolomite or 
 magnesian limestone, with layers of marl, limestone, and gypsum. No. 3, Lime- 
 stone with corals Favosites, etc. Nos 5, n, 15, 17, Ma'Hs with layers of 
 Dolomite and anhydrous gypsum. Nos. 6, 8, 10, 12, 14, 16, Rock salt. 
 
6 THE CHAIN OF LIFE. 
 
 produced by accumulation of corals and shells. Such deposits 
 must not only have been successive, but must have required 
 a long time for their formation. 
 
 In Fig. 4 we have a bed of coal and its accompaniments. 
 The coal itself was produced by the slow accumulation ot 
 vegetable matter on a water-soaked soil, and this was buried 
 
 FIG. 4. Inclined beds, holding fossil plants. Carboniferous. South Joggins, Nova Scotia. 
 
 i. Shale and sandstone. Plants with Spirorbis attached ; rain marks (?). 
 
 le, 8 feet. Erect Calamites. ) An erect coniferous (?) tree, 
 
 rooted 
 
 on the shale, passes up through 15 
 feet of the sandstones and shale. 
 
 2. Sandstone and shal 
 
 3. Gray sandstone, 7 feet. 
 
 4. Gray shale, 4 feet. 
 
 5. Gray sandstone, 4 feet. 
 
 6. Gray shale, 6 inches. Prostrate and erect trees, with rootlets, leaves, Naiadites, and 
 
 Spirorbis on the plants. 
 
 7. Main coal-seam, 5 feet coal in two beds. 
 
 8. Underclay, with rootlets. 
 
 under successive beds of sand and clay, now hardened into 
 sandstone and shale, some of the beds holding trees and reed- 
 like plants, which still stand on the soils on which they grew, 
 and which must have been buried in sediment deposited in 
 inundations or after subsidence of the land. In this section 
 we may also observe that the beds are somewhat inclined ; 
 
PRELIMINARY CONSIDERATIONS. 7 
 
 and that this is not their original position is shown by the 
 posture of the stems of trees, once erect, but now inclined 
 with the beds. This leads to a consideration very important 
 with reference to our present subject ; namely, that as our con- 
 tinents are mostly made up of beds deposited under water and 
 afterwards elevated, these beds have in this process experienced 
 such disturbances that they rarely retain their horizontal posi- 
 tion, but are tilted at various angles. When we follow such 
 inclined strata over large areas, we find that they undulate in 
 great waves or folds, forming what are called anticlinal and 
 synclinal lines, and that the irregularities of the surface of the 
 land depend to a great extent on these undulations, along with 
 the projection of hard beds whose edges protrude at the sur- 
 face. In point of fact, as shown in Fig. 5, mountain ranges 
 depend on these crumplings of the earth's crust; and the 
 
 FIG. 5. Ideal section of the Apalachian Mountains showing folding of the earth's 
 
 crust. 
 
 a, Anticlinal axes, b, Overturned strata, c, Synclinals, d, Unconformable beds. 
 
 primary cause of these is probably the shrinkage of the mass 
 of the earth owing to contraction in cooling. When the dis- 
 turbances of beds are extreme, they often cause intricacies of 
 structure difficult to unravel ; but when of moderate extent 
 they very much aid us in penetrating below the surface, for 
 we can often see a great thickness of beds rising one from 
 beneath another, and can thus know by mere superficial ex- 
 amination the structure of the earth to a great depth. It thus 
 happens that geologists reckon the thickness of the stratified 
 
8 THE CHAIN OF LIFE. 
 
 deposits of the crust of the earth at more than 70,000 feet, 
 though they cannot penetrate it perpendicularly to more than 
 a fraction of that depth. The two sections, Figs. 6 and 7, 
 showing the sequence of beds in England and in the northern 
 part of North America, will serve, if studied by the reader, to 
 show how, by merely travelling over the surface and measuring 
 the upturned edges of beds, many thousands of feet of deposits 
 may be observed, and their relative ages distinctly ascertained. 
 
 In studying any extensive section of rock we find that its 
 members may more or less readily be separated into distinct 
 groups. Sometimes these are distinguished by what is termed 
 unconformability, that is, the lower series has been disturbed 
 or inclined before the upper has been deposited upon it. This 
 is seen on a grand scale in the section Fig. 7, in the case of 
 the Laurentian and Cambrian formations, and on a smaller 
 scale in Fig. 8 in the unconformable superposition of Devonian 
 conglomerate on Silurian slates at St. Abb's Head. In the last 
 section it is quite evident that the beds of the lower series 
 have been bent into abrupt folds and worn away to a con- 
 siderable extent before the deposition of the overlying series. 
 In such a case we know not merely that the upper series is 
 newer than the lower, but that some considerable time must 
 have elapsed after the deposition of the one before the other 
 was laid down ; and we are not surprised to find that the 
 fossils in the groups thus unconformable to each other are very 
 different. 
 
 But even when the beds are conformable, they can usually 
 be separated into groups, depending upon differences of mineral 
 character, or changes which have occurred in the mode of 
 deposition. One group of beds, for example, may be largely 
 composed of limestone, another of sandstone or shale. One 
 group may be distinguished by containing some special mineral, 
 zs, for example, rock salt or coal, while others may be destitute 
 of such special minerals. One group may show by its fossils 
 that it was deposited in the sea, others may be estuarine or 
 
PRELIMINARY CONSIDERATIONS. 
 
 5: ;3- 
 
io THE CHAIN OF LIFE. 
 
 lacustrine. Thus we obtain the means of dividing the rocks 
 of the earth into groups of different ages, known as " Forma- 
 tions," and marking particular periods of geological time. 
 By tracing these formations from one district or region to 
 another, we learn the further truth that the succession is not 
 merely local, but that, though liable to variation in detail, 
 its larger subdivisions hold so extensively that they may be 
 regarded as world-wide in their distribution. 
 
 Putting together the facts thus obtained, we can frame a 
 tabular arrangement of the earth's strata, as in the table pre- 
 fixed to this chapter ; and when we add the further discovery, 
 very early made by geologists, that the successive formations 
 
 FiG. 8. Unconfjrmable superposition of Devonian conglomerate on Silurian slates, a 
 St. Abb's Head, Berwickshire. After Lyell. 
 
 differ from each other in their fossil remains, we have the means 
 of recognising any particular formation by its fossils, even when 
 the stratigraphical evidence may be obscure or wanting. Thus 
 our knowledge of Epochs of Life, and indeed of the whole 
 geological history of the earth, is based on the superposition 
 of beds in the earth's crust, and on the diversity of fossil re- 
 mains in the successive beds so superimposed on each other ; 
 and it is on these grounds that we are enabled to construct a 
 Table of Geological Formations representing the whole series 
 of beds as far as known, with the characteristic groups of fossils 
 of each period. Here I might close these preliminary con- 
 siderations, but there are a few accessory questions, important 
 to our clear comprehension of the subject, which may profitably 
 occupy our attention for a short time. 
 
PRELIMINARY CONSIDERATIONS. n 
 
 One of these relates to the absolute duration of the time 
 represented by the geological history of the earth. Such 
 estimates as our present knowledge enables us to form are 
 very indefinite. Whether we seek for astronomical or geo- 
 logical data, we find great uncertainty. To such an extent is 
 this the case, that current estimates of the time necessary to 
 bring the earth from a state of primitive incandescence to its 
 present condition have varied from fifteen millions of years 
 to five hundred millions. Of the various modes proposed, 
 perhaps the most satisfactory as well as instructive is that 
 based on the rate of denudation of our present continents, as 
 indicated by the amount of sediment carried down by great 
 rivers. The Mississippi, draining a vast and varied area in 
 temperate latitudes, is washing away the American land at the 
 rate of one foot in 6,000 years. The Ganges, in a tropical 
 climate and draining many mountain valleys, works at the rate 
 of one foot in 2,358 years. The mean of these two great 
 rivers would give one foot in 4,179 years, at which rate our 
 continents would be levelled with the waters in about six 
 millions of years. But the land has been in process of renewal 
 as well as of waste in geological time ; and a better measure 
 will be afforded by the amount of beds actually deposited. 
 The entire thickness of all the stratified rocks of Great Britain 
 has been calculated by Ramsay at 72,000 feet. Now, if we 
 suppose the waste in all geological time to have been on the 
 average the same as at present, and that this material has been 
 deposited to the thickness of 72,000 feet on a belt of sea 
 margin 100 miles in width, we shall have about 86 millions of 
 years as the time required. 1 This has the merit of approxi- 
 mating to Sir William Thomson's calculation, based on the rate 
 of cooling of the earth, that a minimum of 100 millions of 
 years may represent the time since a solid crust first began to 
 form. As it is more likely that the rate of denudation has on 
 
 1 Croll has elaborated this calculation in his work, Climate and Time, 
 
12 THE CHAIN OF LIFE. 
 
 the average been greater in former geological periods than at 
 present, we may perhaps estimate fifty or sixty millions of 
 years as the time required for the accumulation of all our 
 formations. Some geologists object to this as too little, but 
 in this some of them are influenced by the exigencies of 
 theories of evolution, and others appear to have no adequate 
 conception of the vast lapse of time represented by such 
 numbers, in its relation to the actual rates of denudation and 
 deposition. 
 
 It should be mentioned here, however, that, on certain 
 theories now somewhat generally accepted, respecting the 
 nature and source of solar heat, the absolute duration of 
 geological time would be much reduced below the estimate 
 of Sir Wm. Thomson, Prof. Tait has based on such data an 
 estimate of fifteen millions of years. Prof. Simon Newcomb 
 says that " on the only hypothesis science will now allow us to 
 make respecting the source of the solar heat " (the gravitation 
 hypothesis of Helmholtz) " the earth was, twenty millions of 
 years ago, enveloped in the fiery atmosphere of the sun." 
 Dr. Kirkwood has called attention to these results in con- 
 nection with the planetary hypothesis of La Place, in the 
 Proceedings of the American Philosophical Society^ Should 
 such views prove to be well-founded, geological calculations 
 as to the time required for the successive formations may have 
 to be revised. 
 
 If now we attempt to divide this time among the formations 
 known to us, according to their relative thicknesses, we have, 
 according to an elaborate estimate of Professor Dana, the time 
 ratios of 12, 3, and i for the Palaeozoic, Mesozoic, and Cainozoic 
 periods respectively. Taking the whole time since the begin- 
 ning of the Cambrian as forty-eight millions of years, we should 
 thus have for the Palaeozoic thirty-six millions, for the Mesozoic 
 nine, and for the Tertiary three. Another calculation, recently 
 
 1 Sept. 1879. 
 
PRELIMINARY CONSIDERATIONS. 13 
 
 made by Professors Hull and Haughton, gives the following 
 ratios : 
 
 Azoic ... . . . 34 '3 per cent. 
 
 Palaeozoic ....... 42*5 ,, 
 
 Mesozoic and Cainozoic . 23*2 ,, 
 
 This calculation is, however, based on the absolute thickness 
 of the several series as ascertained in Great Britain, without 
 reference to the nature of the beds, as indicating different rates 
 of accumulation. Under either estimate it will be seen that 
 the Palaeozoic time greatly exceeds the Mesozoic and Caino- 
 zoic together, and consequently that changes of life seem to 
 have proceeded at an accelerated rate as time wore on. 
 
 Another inquiry of some importance relates to the manner 
 of preservation of fossils, and the extent to which they consti- 
 tute the material of rocks. This inquiry is doubly important, 
 as it bears on the genuineness of fossil remains, and on the 
 means we have of understanding their nature. 
 
 Some rocks are entirely made up of matter that once was 
 alive, or formed part of living organisms. This is the case 
 with some limestones, which consist of microscopic shells, or 
 of larger shells, corals, and similar calcareous organisms, either 
 entire or broken into fragments and cemented together with 
 pasty or crystalline limestone filling their interstices. This 
 may be seen in Fig. 9, which represents a magnified slice of a 
 Silurian limestone. Coal in like manner consists of carbonised 
 vegetable matter, retaining more or less perfectly its organic 
 structure, and sometimes even the external forms of its consti- 
 tuent parts. More frequently, fossils are dispersed more or less 
 sparsely through the substance of beds composed of earthy 
 matter ; and they have usually been more or less affected by 
 chemical changes, or by mechanical pressure, or are mineral- 
 ised by different substances which have either filled their pores 
 by infiltration or have more or less completely replaced their 
 substance. Of course, as a rule, the softer and more putrescible 
 organic matters have perished by decay, and it is only the 
 
14 THE CHAIN OF LIFE. 
 
 harder and more resisting parts that remain. Even these have 
 often yielded to the enormous pressure to which they have 
 been subjected, and if at all porous, have been changed by the 
 slow action of percolating water charged with various kinds of 
 mineral matter in solution. 
 
 It thus happens that many fossils are infiltrated with mineral 
 matter. Wood, for example, may have the cavities of its cells 
 
 FIG. 9. Section of Trenton limestone, magnified, showing that it is composed ot 
 fragments of corals, crinoids, and shells. Montreal. 
 
 and vessels filled with silica or silicates, with sulphide or car- 
 bonate of iron, or with limestone, while the woody walls of the 
 cells may remain either as coaly matter or charcoal. I have 
 often seen the microscopic cells of fossil wood not only filled 
 in this way, but presenting under a high power successive coats 
 of deposit, like the banded structure of an agate. 
 
 In some cases not only are the pores filled with mineral 
 
PRELIMINARY CONSIDERATIONS. 15 
 
 matter, but the solid parts themselves have been replaced, and 
 the whole mass has actually become stone, while still retaining 
 its original structure. Thus silicified wood is often as hard and 
 solid as agate, and under the microscope we see that the wood 
 has entirely perished, and is represented by silica or flint, dif- 
 fering merely in colour from that which fills the cavities. In 
 this case we may imagine the wood to have been acted on by 
 
 n 
 
 FIG. 10. Diagram showing different state of fossilisation of a cell of a tabulate coral 
 (Dawson's Dawn of Life). 
 
 a Natural condition, wall calcite cell empty, b Wall calcite, cells filled with the same. 
 c Walls calcite, cells filled with silica or a silicate, d Wall silicified, cells filled with 
 calcite. e Wall silicified, cell filled with silica. 
 
 water holding in solution silica, combined with soda or potash, 
 in the manner of what is termed soluble glass. The wood, in 
 decay, would be converted into carbon dioxide, and this as 
 formed would seize on the potash or soda, leaving the silica in 
 an insoluble state, to be deposited instead of the carbon. Thus 
 each particle of the carbon of the wood, as removed by decay, 
 would be replaced by a particle of silica, till the whole be- 
 came stone. By similar chemical changes corals and shells 
 are often represented by silica, or by pyrite, which has taken 
 the place of the original calcareous matter ; and still more 
 remarkable changes sometimes occur, as when the siliceous 
 spicules of sponges have been replaced by carbonate of lime. 
 The organic matter present in the fossils greatly promotes these 
 changes, by the substances produced in its decay, and thus it 
 often happens that the shells, corals, etc., contained in lime- 
 stone have been replaced by flint, while the inclosing lime- 
 stone is unchanged. Fig. 10 shows the various conditions 
 
i6 
 
 THE CHAIN OF LIFE. 
 
 which a coral may assume under these different modes of 
 treatment. 
 
 The substance of a fossil may be entirely removed by decay 
 or solution, leaving a mere mould representing its external 
 form, and this may subsequently be filled with mineral matter, 
 so as to produce a natural cast of the object. This is very 
 
 common in the case of fossil 
 plants ; and large trunks of 
 trees . may sometimes be 
 found represented, as seen 
 in Fig. n, by stony pillars 
 retaining nothing of the 
 original wood except per- 
 haps a portion of the bark 
 in the state of coal. It 
 sometimes happens that the 
 substance of fossils has been 
 removed, leaving mere empty 
 cavities, sometimes con- 
 taining stony cores repre- 
 senting the internal chambers 
 of the fossils. Again, cal- 
 careous fossils imbedded in 
 hard rocks are often removed 
 by weathering, leaving very 
 perfect impressions of their 
 forms. For this reason the 
 fossil remains contained in 
 some hard resisting rocks 
 
 can be best seen as impressed moulds on the weathered 
 surfaces. 
 
 Lastly, we sometimes have impressions or footprints repre- 
 senting the locomotion of fossil animals, rather than the fossils 
 themselves. In this way some extinct creatures are known to 
 us only by their footsteps on sand or clay, once soft, but now 
 
 FIG. ii. Cast of erect tree (Sigillaria) in 
 sandstone, standing on a small bed of 
 coal, South Joggins, Nova Scotia (Daw 
 son's Acadian Ge< 
 
PRELIMINARY CONSIDERATIONS. 17 
 
 hardened into stone ; and in the case of some of the lower 
 animals the trails thus made are often not easily interpreted 
 (Figs. 12, 120). It has been found that even sea-weeds drifted 
 
 FIG. 12. Protichnites septem-notatus. A supposed series of crustacean foot-prints n.acL 
 in sand, now hardened into sandstone. Cambrian. After Logan. 
 
 by the tide make impressions of this kind, which, when they 
 occur in old rocks, are very mysterious. Even rain-drops are 
 capable of being permanently impressed on rocks, and con- 
 stitute a kind of fossils. Besides these we have many kinds of 
 imitative markings which simulate fossils, as those of concre- 
 tions or nodules, which are often very fantastic in shape, those 
 of [dendritic crystallisation giving moss-like forms, and the 
 
 c 
 
iS 
 
 THE CHAIN OF LIFE, 
 
 complicated tracery produced on muddy shores by the little 
 rills of water which follow the receding tide (Fig. 13). Such 
 things are often mistaken by the ignorant for fossil remains, 
 but are easily distinguished by a practised eye. 
 
 The reader who has followed these, perhaps somewhat dry, 
 
 FIG. i2<z. Footprints of modern Limulus, or king-crab, in the sand, which enable us to 
 interpret those in Fig. 12. 
 
 details, will be rewarded for his patience by having some 
 conception of the conditions in which we find fossil remains, 
 and of the evidence by which we can refer these to different 
 periods in the history of the earth. 
 
 Carrying this knowledge with us, and at the same time 
 
 FIG. 13. Current markings on shale, resembling a lossil plant, 
 photograph (Dawson's Acadian Geology), 
 
 Reduced from a 
 
 glancing at the table of successive formations prefixed to 
 this chapter, we shall be prepared, without any additional 
 geological study, to understand the statements to be made in 
 the following chapters, and to appreciate the actual nature of 
 the succession of life in so far as it is at present known. 
 
C 2 
 
MAGNIFIED AND RESTORED SECTION OF A PORTION OF EOZOON 
 CANADENSE. 
 
 The shaded portions show the animal matter of the Chambers, Tubuli, Canals, and 
 Pseudopodia ; the unshaded portions the calcareous skeleton. 
 
CHAPTER II. 
 
 THE BEGINNING OF LIFE ON THE EARTH. 
 
 THE day must have been when the first living being appeared 
 for the first time on our planet. Was it plant or animal ? 
 or a generalised organism uniting in some mysterious way 
 the properties and powers of two kingdoms of nature, now so 
 distinct, and even contrary to each other in their manifestations ? 
 Did it appear suddenly, or was it slowly evolved from dead 
 matter by some process in which the albuminous or proto- 
 plasmic matter, which we know forms the basal substance o 
 living beings, was first produced and then endowed with life ? 
 Did the first living being appear in a mature state, or was it 
 merely a germ from which the mature individual could be pro- 
 duced ? These are questions which science in its present state 
 has no means of answering. We do not know any process by 
 which the ingredients of protoplasm can be combined so as to 
 produce that substance without a previous living being. We 
 do not know what molecular differences may exist between 
 dead albumen and that which we see growing and moving and 
 instinct with life ; still less do we know how to set up or estab- 
 lish these differences. We do not know the precise nature or 
 relation to other forces of the energy which actuates living 
 organisms. In our experience the simplest creatures that have 
 life spring from previous germs, themselves the products of 
 previous generations of living beings. Thus we are in the 
 
22 THE CHAIN OF LIFE. 
 
 presence of great mysteries which it might be impossible for us 
 to solve, even if we were permitted to visit some new planet on 
 which the dawn of life was breaking. 
 
 Some things, however, we can infer as to the conditions of 
 the introduction of life. 
 
 First, there is every reason to believe that the earth we 
 inhabit was once a glowing, incandescent mass, condensing 
 from a vaporous condition, and quite unfit for the abode of 
 living beings, and which, even if in some previous state its 
 materials had constituted the mass of an inhabited world, must 
 have lost every trace of any living germ in the fervent heat to 
 which it had been subjected. There must, therefore, have been 
 in some way an absolute creation or origination of life and 
 organisation. 
 
 Secondly, we may infer that in the earlier stages of the 
 earth, when it was perhaps wholly or almost entirely covered 
 with the waters, when it was still uniformly warmed with its 
 own internal heat, when it was surrounded with a pall of 
 dense vapours preventing radiation, and nursing its heat within 
 itself, though in a condition entirely unsuited to the higher 
 forms of life, it may have presented circumstances more 
 favourable to the origination and multiplication of living beings 
 of low organisation than at any subsequent time. This incu- 
 bation of creative power in the vaporous mantle over the 
 primaeval ocean was a favourite imagination of old thinkers, 
 and is not obscurely hinted at in the Book of Genesis. It 
 has been revived and much insisted on by evolutionists in our 
 own time, though it has no certain foundation in scientific 
 observation or experiment. 
 
 Thirdly, from the fact that plant-life alone has the power of 
 subsisting on inorganic matter, and that plants furnish all the 
 nourishment of animals, we may fairly infer that the life of the 
 plant preceded that of the animal. It has, indeed, been 
 suggested that some of the humbler forms of life may combine 
 in a rude and simple way enough of the powers of the plant 
 
THE BEGINNING OF LIFE ON THE EARTH. 23 
 
 and the animal to enable them to bridge over the double gap 
 between the animal and the plant, and the animal and the 
 mineral, or that such creatures may in their early stages 
 carry on vegetable functions, and in their later those of the 
 animal. It is theoretically possible that life may have begun 
 with such creatures, which some of the results of micro- 
 scopical research would lead us to believe still exist. It is, 
 however, on the whole more probable that simple plants first 
 existed, and furnished pabulum to animals of low grade intro- 
 duced almost contemporaneously. 
 
 Fourthly, all our knowledge of the succession of life leads us 
 to believe that it was not the higher plants and animals that 
 first sprang into existence from the teeming earth, but creatures 
 of low and humble organisation, suited to the then immature 
 and unfinished condition of the planet. It is also in accordance 
 with the amazing fecundity of the seas in all geological periods 
 in these lower forms of life, to suppose that the earliest living 
 things originated in the waters, and that the plants and animals 
 of the land are of later date. 
 
 Do we know anything from actual observation of this earliest 
 population of the world ? Such knowledge we can hope to 
 acquire only by studying the oldest formations known to us ; 
 and these, it must be confessed, exist in a state so highly crys- 
 talline, and so much affected by internal heat, by mechanical 
 pressure, and by movement, as to render it little likely that 
 organic remains should be preserved in them in a state fit for 
 recognition. 
 
 In many parts of the world, and notably in Canada and 
 Scandinavia, as well as in Wales, -Scotland, and Bavaria, the 
 older Palaeozoic rocks, the lowest containing plants in great 
 abundance, rest on still older crystalline beds, which have 
 become hard and crystalline in pre-Palseozoic times, and have 
 contributed sand and pebbles to the succeeding very ancient 
 deposits. These old rocks the Eozoic series of our table may- 
 be grouped in two great systems, the Laurentian and Huronian 
 
24 THE CHAIN OF LIFE. 
 
 (Fig. 14). The former may be conveniently divided into three 
 members : First, the Bojian, or Ottawa gneiss, consisting of 
 stratified granite rocks, usually of a red colour, and of very 
 great thickness. This contains, so far as known, no limestone, 
 and has afforded as yet no trace of fossils. Secondly, the 
 Middle Laurentian, the greater part of which consists of gneiss, 
 but containing important beds of other rocks, as quartzite, iron 
 ore, and limestone. It is in this series that we have the first 
 evidence of life, and it is here also that we find the greatest 
 abundance of carbon, in the form of graphite or plumbago, 
 and also large quantities of calcium phosphate, or bone earth. 
 Thirdly, the Upper Laurentian or Norian series. This consists 
 in great part of Labadorite, or lime feldspar, but has also beds 
 of ordinary gneiss, limestone, and iron ore. 
 
 a b c d 
 
 FIG. 14. Ideal section, showing the relations of the Laurentian and Huronian. 
 
 , Lower Laurentian. b, Middle Laurentian. c, Upper Laurentian. d, Huronian. 
 e, Cambrian and Silurian. 
 
 The latter, the Huronian, is much less crystalline, and is 
 divisible into two series the Lower Huronian, which includes 
 many beds of volcanic origin, and the Upper Huronian, which 
 has afforded some obscure fossils. The Huronian was first 
 recognised by Sir W. E. Logan in Canada, but corresponding 
 rocks exist in Europe. The Pebidian series of Hicks in Wales 
 is probably of this age. 
 
 It is likely that much of the present appearance and con- 
 dition of the most ancient rocks may be attributed to meta- 
 morphism, that is, to the slow baking under the influence of 
 heat, heated water, and pressure, to which they have been 
 subjected in the lower parts of the earth's crust, when buried 
 deeply under newer deposits. It is also true, however, as 
 
THE BEGINNING OF LIFE ON THE EARTH. 25 
 
 Dr. Sterry Hunt has pointed out in detail, that they present 
 mineral characters which show a mode of deposition different 
 from that which has prevailed subsequently, and probably 
 indicating great ejections of heated mineral matter into the 
 primitive ocean, and comparatively little of that deposit 
 therein of mere sand and clay which has prevailed in sub- 
 sequent geological periods. In short, these rocks have an 
 unmistakably primitive aspect, distinguishing them from those 
 of later times, and conveying the impression that they approach 
 at least to the records of that time when a heated ocean first 
 rested on the thin and recently solidified crust of our planet. 
 If this is really the case, then our Lower Laurentian hard, 
 compact, destitute of limestone, and composed of material 
 which may be little else than the debris of products of internal 
 heat merely spread out into bedded forms by water may 
 represent a time when no living thing as yet tenanted the 
 waters ; and the dawn of life may have appeared in that period 
 when the Middle Laurentian beds were laid down. Here at 
 least we find two kinds of evidence pointing to the existence 
 of certain forms of life in the waters. 
 
 The first depends on the mineral character of the beds 
 themselves. This formation holds several very thick beds of 
 limestone. Now although this kind of rock may, under certain 
 circumstances, be deposited directly from solution in water, it 
 is not ordinarily so deposited, but more usually through the 
 agency of living beings inhabiting the waters, and forming 
 their skeletons or hard parts of limestone derived from the 
 water, usually through the medium of humble forms of plant 
 life. In this way are formed reefs of coral and beds of shells 
 and of chalky ooze, all composed of material once constituting 
 the skeletons of animals. The study of limestones of all 
 geological ages shows that this has been the usual mode of 
 their formation. If the Laurentian limestones had a similar 
 origin, the seas of that period must have swarmed with animals 
 having calcareous coverings j and the study of more modern 
 
26 THE CHAIN OF LIFE 
 
 limestones which have become highly crystalline shows that it 
 is quite possible that the forms and structures of these organisms 
 may have been obliterated. 
 
 Again, the Middle Laurentian abounds in carbon or coaly 
 matter. True, this is in the form of graphite or plumbago, 
 but this condition may be a result of metamorphism ; and we 
 know that the carbon of coal-beds and bituminous shales of 
 much more modern times has been altered into graphite. 
 Further, the graphite occurs in the way in which we should 
 expect it to occur if of organic origin. It is found dissemi- 
 nated in the limestone, just as bituminous matter is found in 
 unaltered rocks of this kind. It is found interlaminated with 
 gneiss, as carbonaceous and bituminous matters are found in 
 the shales of the ordinary fossiliferous rocks, where these 
 substances are known to be of organic origin. The graphite 
 also occurs in a very pure form in irregular veins, just as in 
 some bituminous formations the rock oil, oozing into fissures, 
 has been hardened into asphalt or coaly matter. 1 
 
 To these facts may be added the presence of thick beds 
 and veins of iron ore and of apatite or calcium phosphate 
 (bone earth). Both of these substances occur in a dis- 
 seminated state in nearly all rocks, but they are concen- 
 trated into definite deposits by the action of life. Iron is 
 usually dissolved out and redeposited by acids produced in 
 the decay of vegetable matter, as we see in the clay iron- 
 stones of the coal formation and in bog-iron ores. Calcic 
 phosphate is taken up by many animals, and forms their shells 
 or skeletons, and on their death is deposited in beds on the 
 sea-bottom, sometimes to a very considerable extent. 
 
 The concurrence of all these phenomena in the Middle 
 
 1 Analyses recently made by Mr. C. Hoffman, of the Geological Survey 
 of Canada, show that beds of graphitic gneiss, some of them 8 feet in 
 thickness, contain as much as 25-5 to 30 per cent, of carbon, the remaining 
 earthy matter consisting principally of silica, alumina, and lime. The 
 graphite from veins was nearly pure carbon, containing from 97*6 to 99 - 8 
 per cent, of that substance. 
 
THE BEGINNING OF LIFE ON THE EARTH. 27 
 
 Laurentian may be held to afford a strong presumption that, 
 could we discover these rocks in an unaltered state, we should 
 find the limestones filled with marine fossils and the graphite 
 showing the forms or structure of plants. The only startling 
 feature in this conclusion is, that if we admit it, we must 
 also admit that life was developed in the Laurentian time in 
 an exuberance not surpassed, if equalled, in any" subse- 
 quent period. Still, there is nothing incredible in this, for 
 if the forms of life were few and low, their increase may 
 have been rapid, because unchecked ; and they no doubt 
 found in the ancient seas a surplusage of material on which 
 to feed and with which to construct their skeletons. Dr. 
 Hunt has estimated that the amount of carbon now sealed up 
 as coaly matter would, if diffused in the atmosphere as carbon 
 dioxide, afford 600 times the quantity of that gas at present 
 floating in the air. A still more vast amount is sealed up in 
 the limestone of the several geological formations. The same 
 chemist has shown that the quantity of lime held in solution 
 in the ocean must have been much greater in Laurentian times 
 than at present. These facts at least allow us to suppose that 
 in the Eozoic times there were great supplies of carbon and of 
 lime available to such creatures of low organisation as were 
 capable of profiting by them ; and we have no reason to doubt 
 that there may have been plants and animals so constituted as 
 to flourish in conditions of this kind, in which perhaps scarcely 
 any modern species could exist. 
 
 These probabilities have caused geologists anxiously to 
 search for any traces of fossil organic remains in the old 
 Laurentian rocks ; and they have been rewarded by the dis- 
 covery of one species, Eozoon Canadense, still often referred to 
 as only a problematical fossil ; but this arises to a large extent 
 from the prevalent want of knowledge sufficient to appreciate 
 the evidence for its organic character. This being once 
 admitted, we have in the existence of Eozoon alone a suffi- 
 cient cause for the accumulation of much of the Laurentian 
 
28 THE CHAIN. OF LIFE. 
 
 limestone, though there is reason to believe that it was not 
 the only inhabitant of those ancient seas. 
 
 The best specimens of Eozoon occur as rounded, flattened, 
 or more or less irregular lumps or masses in certain layers of 
 the Laurentian limestone. " When weathered on the surface 
 
 FIG. 15 (Nos. i to 4). Small weathered specimen of Eozoon. From Petite Nation. 
 
 i, Natural size ; showing general form, and acervuline portion above and laminated 
 portion below. 2, Enlarged casts of cells from upper part. 3, Enlarged casts of 
 cells from the lower part of the acervuline portion. 4, Enlarged casts of sarcode layers 
 from the laminated part. 
 
 of the rock, these lumps show a regular concentric lamina- 
 tion, caused by thin fibres of limestone, alternating with other 
 mineral substances, filling up the spaces between them. When 
 these intervening layers are composed of such minerals as 
 Serpentine, Loganite, Pyroxene, or Dolomite, which are more 
 
THE BEGINNING OF LIFE ON THE EARTH. 29 
 
 resisting than the limestone, they project when weathered, or 
 when the limestone is etched by an acid, so as to show the 
 lamination very distinctly. At the lower surface of the masses 
 the layers are seen to be thicker than they are above, and in 
 perfect specimens they are seen toward the surface to break up 
 
 FIG. 16. Nature-printed specimen of Eozoon slightly etched with acid. It shows the 
 lamination, and at one side fragmental Eozoon (Life's Dawn on Earth). 
 
 into small rounded vesicles of calcite, like little bubbles, which 
 constitute the so-called acervuline condition of Eozoon (Fig. 
 15, No. 2). Slices of the fossil etched with an acid show 
 these appearances very perfectly, and can even be printed 
 from, so as to present perfect nature-prints of the structure 
 (Fig. 16). 
 
 On etching a small fragment or slice with very dilute acid, 
 
30 THE CHAIN OF LIFE. 
 
 so as to dissolve away the calcite slowly, if the specimen be 
 well preserved, we find that the calcite layers have a very 
 curious structure. This is indicated by the appearance of 
 little white or transparent threads of Serpentine, Dolomite, 
 or Pyroxene, which ramify throughout the substance of the 
 limestone layers, and are left intact when they have been 
 dissolved. These little processes must originally have been 
 pores in the limestone layers, which have been filled with 
 the substance which constitutes the alternate laminae. In 
 addition to this, if we use a somewhat high microscopic power, 
 and especially if we study the structures as seen in thin trans- 
 parent slices, we can perceive a still finer tubulation along the 
 sides of the calcite layers, represented by extremely minute 
 parallel rods of mineral matter (Figs. 17, 18). 
 
 Now if we regard these structures as those of an infiltrated 
 fossil, as described in last chapter, their interpretation will not 
 be difficult. The original organism was composed of calcareous 
 matter in thin concentric laminae, connected with each other 
 by pillars and plates of similar material. Between these 
 laminae was lodged the soft, jelly-like substance of a marine 
 animal, growing by the addition of successive layers, each pro- 
 tected by a thin calcareous crust. The layers were originally 
 traversed by very numerous parallel tubuli, permitting the soft 
 protoplasm to penetrate them ; and when, in the progress of 
 growth, it was necessary to strengthen these layers, they were 
 thickened by a supplemental deposit traversed by larger and 
 ramifying canals. When the animal was dead, and its soft parts 
 removed by decay, the chambers between the laminae, as 
 well as the minute canals and tubuli, became infiltrated with 
 mineral matter, in the manner described in the last chapter, 
 and when so preserved became absolutely imperishable under 
 any circumstances short of absolute fusion. 
 
 This interpretation leads to the conclusion, at which I arrived 
 from the study of the first well-preserved specimen ever 
 submitted to microscopic examination, that the animal which 
 
THE BEGINNING OF LIFE ON THE EARTH. 31 
 
 FIG. 17. Magnified group of canals in supplemental skeleton of Eozoon. 
 Taken from the specimen in which they were first recognised (Life's Dawn on Earth'}. 
 
 FIG. 18. Portion of Eozoon magnified 100 diameters, showing the original cell-wall with 
 tubulation, and the supplemental skeleton with canals. After Carpenter. 
 
 a, Original tubulated wall or " Nummuline layer." More magnified in Fig. A. 
 b, c, Intermediate skeleton, with canals. 
 
32 THE CHAIN OF LIFE. 
 
 produced the calcareous skeleton of Eozoon was a member of 
 that lowest grade of Protozoa known as Foraminifera ; and which, 
 after living through the whole of geological time, still abound 
 in the sea. The main differences are, that Eozoon presents 
 a somewhat generalised structure, intermediate between two 
 modern types, and that it attained to a gigantic size compared 
 with most of these organisms in later periods. How near it 
 approaches in structure to some modern forms may be seen by 
 comparison of the recent species represented in Fig. 19, in 
 
 FIG, 19. Magnified portion of shell of Calcarina. After Carpenter 
 a, Cells, b, Original cell-wall with tubuli. c, Supplementary skeleton with canals. 
 
 which the parts corresponding to the chambers, laminae, tubuli, 
 and canals of Eozoon can be readily distinguished. 
 
 The modern animals of this group are wholly composed of 
 soft gelatinous protoplasm or sarcode, the outer layer of which 
 is usually somewhat denser than the inner portion ; but both are 
 structureless, except that the inner layer may present a more 
 
THE BEGINNING OF LIFE ON THE EARTH. 33 
 
 or less distinct granular appearance. Many of them show a 
 distinct spot or cell, called the nucleus, and some have minute 
 transparent vesicles, which contract and expand alternately, 
 and appear to be of the nature of circulatory or excretory 
 organs. They have no proper alimentary canal, but receive 
 their food into the general mass and digest it in temporary 
 cavities. Their means of locomotion and prehension are 
 soft thread-like or finger-like processes, extended at will 
 from the surface of any part of the body, and known as 
 false feet (pseudopodia). From these processes the whole 
 group has obtained the name of Rhizopods, or root footed 
 animals. They may be regarded as constituting the simplest 
 and humblest form of animal life certainly known to us. 
 
 The very numerous species of these creatures existing in the 
 waters of the modern world may be arranged under three prin- 
 cipal groups. The first and highest includes those which have 
 lobate or finger-like pseudopods, and a well-developed nucleus 
 and pulsating vesicle (Fig. 20, a). They are mostly inhabit 
 ants of fresh water, and destitute of a hard crust or shell. A 
 second group, including many inhabitants of the sea as well as 
 of fresh waters, has thread-like radiating pseudopodia 1 (Fig. 
 20 b}. Some of these form beautiful silicious skeletons. A 
 third group, essentially marine, consists of those with reticulated 
 pseudopodia, and usually destitute of distinct nucleus and pul- 
 sating vesicle (Fig. 21). They produce beautiful calcareous 
 skeletons, often very complex, or sometimes are content to 
 cover themselves with a crust of agglutinated grains of sand. 
 It is to this last group that Eozoon belongs, and to the highest 
 division of it that which has the shell perforated with minute 
 pores, often of two kinds. It is curious that just as we have 
 the chambers and pores of Eozoon filled with serpentine, 
 so in all geological formations and in the modern seas it 
 is not uncommon to find Foraminifera having their cavities 
 
 1 Sometimes separated as a distinct order under the name of Radiolaria. 
 
 D 
 
34 
 
 THE CHAIN OF LIFE. 
 
 filled with glauconite and other hydrous silicates allied to 
 serpentine. 
 
 FIG. 20. a, Amoeba, a fresh-water naked Rhizopod ; and b, Actinophrys, a fresh-water 
 Protozoon of the group Radiolaria, with thread-like pseudopodia. 
 
 FIG. 21. Nonionina, a modern marine Foraminifer. Showing its chambered shell and 
 netted pseudopodia. After Carpenter. 
 
 If we attempt to trace the Rhizopods onward from the Middle 
 Laurentian, we are met with a great hiatus in the Upper Lauren- 
 
THE BEGINNING OF LIFE ON THE EARTH. 35 
 
 tian. The species Eozoon Bavaricum has, however, been 
 found in rocks apparently of Huronian age ; but this is the 
 last known appearance of Eozoon, properly so-called. In the 
 Cambrian or Siluro-Cambrian, however, we meet with many 
 gigantic Protozoa, more especially those known as Stromatopora^ 
 Archceocyat/ms, Receptaculites, and Cryptozoon. 
 
 The typical Stromatoporae, or Layer-corals, consist, like 
 
 FIG. 22. Stromatopora concentrica. After Hall. 
 
 a, Section of the same, magnified, b, Small portion highly magnified, showing laminae 
 
 and pillars. 
 
 Eozoon, of concentric layers, connected by numerous pillars, 
 which are often, though not always, more definite and regular 
 than in the Laurentian fossil. The laminae are perforated, but 
 more coarsely than in Eozoon, and they are often thickened with 
 supplemental deposit which, in some of the forms, presents canals 
 radiating from vertical tubes or bundles of tubes penetrating 
 the mass (Figs. 22, 23). The mode of growth of Stromatopora 
 must have closely resembled that of Eozoon, and the forms 
 produced are so similar that it is often quite impossible to 
 
 D 2 
 
36 THE CHAIN OF LIFE. 
 
 distinguish them by the naked eye. Like Eozoon, they form the 
 substance of important limestones, and single masses are some- 
 times found as much as three feet in diameter. The Stromato- 
 porse extend from the Upper Cambrian to the Devonian inclu- 
 sive. In the Carboniferous they are continued by smaller and 
 more regular organisms of the genus Loftusia?- and this genus 
 seems to extend without marked change up to the Eocesie 
 Tertiary. Recent students of the Stromatoporae seem dis- 
 posed to promote them from the province of Protozoa to that of 
 the Hydroids. 2 The reasons for this seem cogent in the case 
 of some of the forms, but in my judgment fail in others, more 
 especially in the older forms. It may ultimately be found that 
 
 FIG. 23. Caicnopora plannlata.. Showing the radiating canals on a weathered 
 surface. Devonian. After Hall. 
 
 the group as now held includes very different types of structure. 
 In modem times I know of no nearer representative than the 
 animal whose skeleton often adheres in red encrusting patches 
 to our specimens of corals, and which is known as Polytrema. 
 In general structure it is not very far from being a very 
 degenerate kind of Stromatopora. 
 
 It is curious that in the line of succession above stated, the 
 beautiful tubulated cell-wall of Eozoon disappears ; and this 
 structure seems, after the Laurentian, to be for ever divorced 
 from the great laminated Protozoans. It reappears in the 
 
 1 Loftusia Columbiana, Dawson, from British Columbia, is the only 
 Carboniferous species yet known. 
 
 2 See Nicholson in the Memoirs of the Palaeontographical Society. 
 
THE BEGINNING OF LIFE ON THE EARTH. 37 
 
 Carboniferous, in certain smaller organisms of the type of the 
 Nummulites, or Money-stone Foraminifers, and is continued in 
 this group of smaller and free animals down to the present time. 
 In the Cretaceous and early Tertiary periods, the Foraminifera 
 of different types have been nearly as great rock-builders 
 as they were in the Laurentian. Some of these later rock- 
 builders, however, have belonged to the lower or imperforate 
 group ; others to the higher or Rotaline and Nummuline groups ; 
 
 FIG. 24. Archceocyathus minganensis. A Primordial Protozoon. After Billings. 
 a, Pores of the inner wall. 
 
 and, as a whole, they have been individually small, making up 
 in numbers what they lacked in size. Probably the conditions 
 for enabling animals of this type rapidly, and on a large scale, 
 to collect calcareous matter, were more favourable in the 
 Laurentian than they have ever been since. 
 
 In the Siluro-Cambrian age two other forms of gigantic 
 Foraminiferal Protozoans were introduced, widely different from 
 Eozoon, and destined apparently not to survive the period in 
 
3 8 THE CHAIN OF LIFE. 
 
 which they appeared. These were Archseocyathus, the ancient 
 Cup-corals, and Receptaculites, which may perhaps be called 
 the Sack-corals. Both are quite remote from Eozoon in 
 structure, wanting its complexity in the matter of minute 
 tubules, and having greater regularity and complication on the 
 large scale. Archseocyathus had the form of a hollow inverted 
 cone with double perforated walls, connected by radiating 
 irregular plates, also perforated (Fig. 24). It has been re- 
 garded as a sponge, and some species are certainly accompanied 
 
 FIG. 25. Receptaculites. Restored. After Billings. 
 
 a, Aperture. b, Inner wall. c, Outer wall. , Nucleus, or primary chamber. 
 z>, Internal cavity. 
 
 with spicules ; but these I have ascertained to be merely acci- 
 dental, and will be referred to in the next chapter. The true 
 structure of Archseocyathus consists of radiating calcareous 
 plates enclosing chambers connected by pores. Archaeocyathus 
 came in with the Later Cambrian, and seems to have died out 
 in the Siluro- Cambrian. The only more modern things which 
 at all resemble it are the Foraminifera called Dactylopora, 
 which belong to the Tertiary period. 
 Receptaculites is a still more complex organism. It has a 
 
THE BEGINNING OF LIFE ON THE EARTH. 39 
 
 sack-like form, often attaining a large size, and the double 
 walls are composed of square or rhombic plates, connected 
 with each other by hollow tubes from which proceed canals 
 perforating the plates (Fig. 25). This curious structure is 
 confined to the Siluro-Cambrian, and is so dissimilar from 
 modern forms that its affinities have been subject to grave 
 doubts. 
 
 We thus have presented to us the remarkable fact that in 
 
 FIG. 26. Section of Loftitsia Persica. An Eocene Foraminifer. Magnified five 
 diameters. After Carpenter and Brady. 
 
 the Palaeozoic age we have no precise representative of Eozoon, 
 but instead three divergent types, differing from it and from 
 each other, all apparently specialised to particular uses, all 
 temporary in their duration ; while in later times nature seems 
 to have returned nearer to the type of Eozoon, though on a 
 smaller scale, and separating some characters conjoined in it. 
 Some portion of this curious result may be due to our ignorance ; 
 and it would be interesting to know, what we may know some 
 
40 THE CHAIN OF LIFE. 
 
 day, how this type of life was represented in the long interval 
 between the Huronian and the Upper Cambrian, when perhaps 
 there may have been forms that would at least enable us to 
 connect Eozoon and Stromatopora. 
 
 Another link in the chain of being remains to be noticed 
 here. In the Laurentian limestones we meet with numerous 
 minute spherical bodies and groups of spheres with calcareous 
 tubulated tests. 1 These may either be small Foraminiferae, 
 distinct from Eozoon, or may be germs or detached cells from 
 its surface. Similar bodies are found in the lower part of the 
 Siluro-Cambrian, in the Quebec group at Point Levis ; and there 
 they are filled with a species of glauconite constituting a sort 
 of greensand rock. Still higher, in the Carboniferous, there are 
 very numerous species of Foraminifera, presenting forms very 
 similar to those in the modern seas, so that in the smaller 
 shells of this group we seem to have evidence of a continuous 
 series all the way from the Laurentian to the present time. The 
 greater laminated forms co-exist with these up to the Eocene 
 Tertiary. Throughout the whole of geological time from the 
 formation of the Laurentian limestones to that of the chalky 
 ooze accumulating in the modern ocean these humble creatures 
 have been among the chief instruments in seizing on the 
 calcareous matter of the waters and depositing it in the form 
 of limestone. 
 
 I have said nothing of the development of higher forms of 
 animal life from Eozoon, simply because I know nothing of it. 
 We shall see in the next chapter that these are introduced 
 seemingly in an independent manner. We may be content to 
 trace foraminiferal life along its own line of development, 
 waxing and waning, but ever confined within the same general 
 boundaries, from the Laurentian to the present time. It is 
 likely that if, in any of the ages constituting this vast lapse of 
 time, a dredge had been dropped into the depths of ocean, 
 
 1 Archaesfheriiut of the author. 
 
THE BEGINNING OF LIFE ON THE EARTH. 41 
 
 it would have brought up Foraminifera not essentially different 
 in form and structure. If any one asks to what extent the suc- 
 cessive species constituting this almost endless chain may be 
 descendants one of the other, we have no absolutely certain 
 information to give. On the one hand, it is not inconceivable 
 thas such forms as Stromatopora or Nummulina may have de- 
 
 FIG. 27. Foraminiferal Rock Builders, in the Cretaceous and Eocene. 
 
 a, Nummulites Icevigata Eocene, b, The same, showing chambered interior, c, 
 Milioline limestone, magnified Eocene, Paris, a, Hard Chalk, section magnified 
 Cretaceous. 
 
 scended from Eozoon. On the other hand, it is equally con- 
 ceivable that the same power which produced Eozoon at first, 
 whether from dead matter or from some unknown lower form 
 of life, may have repeated the process in later times with 
 modifications. In any case it is probable that the Foraminifera 
 have experienced alternations of expansion and shrinkage, 
 
42 THE CHAIN OF LIFE. 
 
 of elevation and decadence, in the lapse of geological time. 
 There were times in which many new forms swarmed into ex- 
 istence, and times in which old forms were becoming extinct 
 without being replaced by others. In so far as the areas of 
 the continents and the adjacent waters are concerned, those 
 periods when the land was subsiding under the ocean must 
 have been their times of prosperity, those in which the crust 
 of the earth shrunk and raised up large areas of land must 
 have been their times of decay. Still this lowest form of animal 
 life has never perished, but has always found abundant place 
 for itself, however pressed by physical change and by the intro- 
 duction of higher beings. 
 
Paradoxides Regina (Matthews). Lower Cambrian of New Brunswick. 
 Jth Nat. Size. 
 
CHAPTER III. 
 
 THE AGE OF INVERTEBRATES OF THH SEA. 
 
 IF the middle portion of the Laurentian age was really a 
 time of exuberant and abounding life, either this met with 
 strange reverses in succeeding periods, or the conditions of 
 preservation have been such as to prevent us from tracing its 
 onward history. Certain it is, that according to present ap- 
 pearances we have a new beginning in the Cambrian, which 
 introduces the great Palaeozoic age, and few links of connection 
 are known between this and the previous Eozoic. 
 
 At the beginning of the Palaeozoic we have reason to believe 
 that our continents were slowly subsiding under the sea, after 
 a period of general continental elevation which was con- 
 sequent on the crumbling of the earth's crust at the close of 
 the Eozoic ; and on the new sea-bottoms formed by this subsi- 
 dence came in, slowly at first, but in ever-increasing swarms, 
 the abundant and varied life of the early Palaeozoic. 
 
 In the oldest portion of the Cambrian series in Wales, Hicks 
 has catalogued species of no less than seventeen genera, em- 
 bracing Crustaceans, the representatives of our crabs and 
 lobsters, bivalve and univalve shell-fishes of different types, 
 worms, sea-stars, zoophytes, and sponges. If we could have 
 walked on the shores of the old Cambrian sea, or cast our 
 dredge or trawl into its depths, we should have found repre- 
 sentatives of most of the humbler forms of sea life still extant, 
 
4 6 
 
 THE CHAIN OF LIFE. 
 
 though of specific forms strange to us. Perhaps the nearest 
 approach to such experience which we can make is to examine 
 the group of Cambrian animals delineated in Fig. 28, and to 
 notice, under the guidance of the geologist above named, the 
 sections seen at St. David's, in South Wales. 
 
 Here we find a nucleus of ancient rocks supposed to be 
 Laurentian, though in mineral character more nearly akin to 
 
 FIG. 28. Group of Cambrian Animals (from Nicholson). 
 
 a, Arenicolites didymus, worm tubes, b, Lingulella ferruginea. c, Theca Davidii. 
 d, Modiolopsis solvensis. e, Orthis Hicksii. f, Obolella sagittalis. g, Hymen- 
 ocaris vermicauda. h, Trilobite, Olenus micrurus. 
 
 the Huronian, but which have hitherto afforded no trace of 
 fossils. Resting unconformably on these is a series of par- 
 tially altered rocks, regarded as Lower Cambrian, and also 
 destitute of organic remains. These have a thickness of 
 almost 1,000 feet, and they are succeeded by 3,000 feet more 
 of similar rocks, still classed as Lower Cambrian, but which 
 have afforded fossils. The lowest bed which contains indica- 
 tions of life is a red shale, perhaps a deep-sea bed, and possibly 
 
THE AGE OF INVERTEBRATES OF THE SEA. 47 
 
 itself partly of organic origin, by that strange process of de- 
 composition or dissolution of foraminiferal ooze and volcanic 
 fragments, going on in the depths of the modern ocean, and 
 described by Dr. Wyville Thomson as occurring over large 
 areas in the South Pacific. The species are two Lingulellce, 
 a Discina and a Leperditia. Supposing these to be all, it is 
 remarkable that we have no Protozoa or Corals or Echinoderms, 
 and that the types of Brachiopods and Crustaceans are of com- 
 paratively modern affinities. Passing upward through another 
 1,000 feet of barren sandstone, we reach a zone in which no 
 less than five genera of Trilobites are found, along with Ptero- 
 pods and a sponge. Thus it is that life comes in at the base 
 of the Cambrian in Wales, and it may be regarded as a fair 
 specimen of the facts as they appear in the earlier fossiliferous 
 beds succeeding the Laurentian. Taking the first of these 
 groups of fossils, we may recognise in the Leperditia a two- 
 valved Crustacean closely allied to forms still living in the seas 
 and fresh waters. The Lingulellse, whether we regard them as 
 molluscoids, or, with Professor Morse, as singularly specialised 
 worms, represent a peculiar and distinct type, handed down, 
 through all the vicissitudes of the geological ages, to the 
 present day. The Pteropods and the sponge are very similar 
 to forms now living. The Trilobites are an extinct group, 
 but closely allied to some modern Crustaceans. Had the 
 primordial life begun with species altogether inscrutable and 
 unexampled in succeeding ages, this would no doubt have 
 been mysterious ; but next to this is the mystery of the oldest 
 forms of life being also among the newest. Whatever the 
 origin of these creatures, they represent families which have 
 endured till now in the struggle for existence without either 
 elevation or degradation. Yet, though thus vast in their 
 duration, they seem to have swarmed in together and in great 
 numbers, in the Cambrian, without any previous preparation. 
 From the Cambrian onward, throughout the whole Palaeozoic, 
 there is no decided break in the continuity of marine life ; and 
 
48 THE CHAIN OF LIFE. 
 
 already in the Silurian period the sea was tenanted with all the 
 forms of invertebrate life it yet presents, and these in a teeming 
 abundance not surpassed in any succeeding age. Let us now, 
 in accordance with our plan, select some of these ancient 
 inhabitants of the waters and trace their subsequent history. 
 
 Remains of sea-weeds are undoubtedly present in the Cam- 
 brian rocks. One of the lowest beds in Sweden has been 
 named from their abundance the Fucoidal Sandstone; and 
 wherever fossiliferous Cambrian rocks occur, some traces, more 
 or less obscure, of these plants may be found. Nearly all that 
 we can say of them, however, is, that, in so far as their remains 
 give any information, they are very like the plants of the same 
 group that now abound in our' seas. In the fucoidal sandstone 
 of Sweden certain striated or ribbed bodies have been found, 
 which have even been regarded as land plants ; 1 but they 
 seem rather to be trails or marks left by sea-weeds dragged 
 by currents over a muddy bottom. The plants of the sea thus 
 precede those of the land, and they begin on the same level 
 as to structure that they have since maintained. I agree with 
 Nathorst, however, in holding that the Bilobites" and many 
 other forms believed by some to be sea-weeds, are really trails 
 and tracks of animals. 2 
 
 The Foraminifera of the Palaeozoic we have noticed in the 
 last chapter ; but we now find a new type of Protozoan that 
 of the Sponge. Sponges as they exist at present may be 
 defined to be composite animals, made up of a great number 
 of one-celled or gelatinous zoids, provided with vibrating 
 threads or cilia, and so arranged that currents of water are 
 driven through passages or canals in the mass, by the action 
 of the cilia, bringing food and aerated water for respiration. 
 To support these soft sarcodic sponge-masses, they secrete 
 fibres of horny matter and needles (spiculae) of flint or of 
 
 1 Eophyton Linn&Unum (Torrell). 
 
 2 See Paper on " Footprints and Impressions of Animals," Am. Journal 
 of Science, 1873. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 49 
 
 limestone, forming complicated fibrous and spicular skeletons, 
 often of great beauty. They abound in all seas, and some 
 species are found in fresh waters. 
 
 With the exception of a very few species destitute of skeleton, 
 and which we cannot expect to find in a fossil state, the 
 sponges may be roughly divided into three groups : i, those 
 with corneous or horny skeleton, like our common washing 
 sponges ; 2, those with skeletons composed of silicious needles 
 of various forms and arrangement ; 3, those with calcareous 
 spicules. Of these, the second or silicious group has pre- 
 
 FIG. 29. Portion of skeleton of Hexactinellid Sponge {Coeloptychii.m}. 
 
 After Zittel. 
 
 Magnified. 
 
 cedence in point of time, beginning in the Early Cambrian, 
 and continuing to the present. Two of its subdivisions are 
 especially interesting in their range. The first is that of the 
 Lattice-sponges (Hexcutinellida), in which the spicules have 
 six rays placed at right angles, and are attached to each other 
 by their points, so as to form a very regular network (Fig. 29). 
 The second is that of the Stone-sponges (Lithistidcz), in which 
 
50 THE CHAIN OF LIFE. 
 
 the spicules are four-rayed or irregular, and are united by the 
 branching root-like ends of the rays. The most beautiful of 
 all sponges, the Venus Flower-basket (Euplectella), is a modern 
 Hexactinellid, and the wonderful weaving of its spicules is as 
 marvellous a triumph of constructive skill as its general form 
 is graceful. The Lithistids are less beautiful, but are the 
 densest and most compact of sponges, and are represented by 
 several species in the modern seas. Both of these types go 
 back to the Early Cambrian, and have continued side by side to 
 the present day, as representatives of two distinct geometrical 
 methods for the construction of a spicular skeleton. 
 
 Many years ago the keen eye of the late lamented Salter 
 
 FIG. 30. Protosfiongia fenestrata (Salter). Menevlan group, a. Fragment showing the 
 spicules partially displaced. &, Portion enlarged. 
 
 detected in a stain on the surface of a slab of Cambrian slate 
 the remains of a sponge ; and minute examination showed that 
 its spicules crossed each other, and formed lattice-work on the 
 hexactinellid plan. Salter boldly named it Protospongia (the 
 first sponge), and it is still the earliest that we know (Fig. 
 30). Thus the type whose skeleton is the most perfect in a 
 mechanical point of view takes the lead. It is continued in 
 the Silurian in many curious forms, of which the stalkless 
 sponges (Astylospongia) are the most common (Fig. 31). It 
 perhaps attains its maximum in the Cretaceous, from which the 
 beautiful example in Fig. 29 is taken, and it still flourishes, 
 giving us the most beautiful of all recent forms. Before the 
 
THE AGE OF INVERTEBRATES OF THE $EA. 51 
 
 close of the Cambrian there were other sponges of the 
 Lithistid type. Fig. 32 represents a group of spicules from 
 
 FIG. 31. Astylospongia. pr&morsa (Roemer). Niagara group. After Hall, 
 a, Spicules magnified. 
 
 the Calciferous (Lowest Silurian or Upper Cambrian) of 
 Mingan, 1 and which probably belong to a large Lithistid sponge 
 
 FIG. 32. Spicules of Lithistid sponge ( Trichospongia of Billings). From the Cambrian 
 of Labrador. 
 
 of that early time. The Lithistids have been recognised in the 
 Upper Silurian and Carboniferous, and continuing upward to 
 the Cretaceous, there become vastly numerous, while their 
 
 1 They probably belong to a large sponge named by Billings Tricho- 
 spongia sericea. 
 
 E 2 
 
52 THE CHAIN OF LIFE. 
 
 modern representatives are by no means few. The silicious 
 sponges with simple spicules appear to have existed as far back 
 as the Siluro-Cambrian, and there is believed to be almost as 
 early evidence of horny or corneous sponges. The calcareous 
 sponges have been recognised as far back as the Silurian. 1 
 Thus from the close of the Palaeozoic all the types of sponges 
 seem to have existed side by side ; and in the Cretaceous period. 
 
 FIG* 33. OldJtamia antiqnct 
 (Forbes). 
 
 Frc. 34. Dictyonema soctale. Enlarged. 
 Lingula flags. After Salter. ] 
 
 when such large areas of our continents were deeply submerged, 
 they attained a wonderful development, perhaps not equalled 
 in any other era of the earth's history. 
 
 Sponges may be regarded as the highest or most complex of 
 the Protozoa or the lowest of the Coelenterates. We have no 
 links wherewith to connect them with the lower Protozoa of the 
 Eozoic period ; .and through their long history, though very 
 numerous in genera and species, they show no closer relation- 
 ship with the Foraminifera below, and the Corals above, than do 
 their successors in the modern seas. They thus stand very 
 1 Amphispongia. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 53 
 
 much apart ; and modern studies of their development and 
 minute structures do not seem to remove them from this isola- 
 tion. Though we are treating here of inhabitants of the sea, 
 it may be proper to mention that Geinitz has described two 
 species from the Permian which he believed to be early precur- 
 sors of the Spongillse, or fresh-water sponges ; but more recently 
 he seems to regard them as probably Algae. Young has, how- 
 ever, recently found true spicules of Spongilla in the Purbeck 
 beds. 1 
 
 A stage higher than the sponges are those little polyp-like 
 animals with sac-like bodies and radiating arms or tentacles, 
 which form minute horny or calcareous cells, and bud out into 
 
 c*. 
 
 
 
 FIG. 35. Dictyontma Websteri (Dn ). Niagara formation, 
 a, Enlarged portion (Acadian Geology). 
 
 branching communities, looking to untrained eyes like delicate 
 sea-weeds the sea-firs and sea-mosses of our coasts (Fig. 36). 
 These belong to a very old group, for in the oldest Cambrian 
 we have a form referred to this type (Fig. 33), and in the 
 Upper Cambrian another still more decided example (Fig. 
 34). 2 This style of life, once. introduced, must have increased 
 in variety and extended itself with amazing rapidity, for in the 
 Siluro-Cambrian age we find it already as characteristic as in 
 our modern seas, and so abundant that vast thicknesses of 
 shale are filled and blackened with the debris of forms allied 
 to the sea-firs, and masses of limestone largely made up of the 
 
 1 Geological Magazine, May, 1878. 
 
 2 It is regarded as somewhat doubtful whether these are Hydroids or 
 Bryozoa. 
 
54 THE CHAIN OF LIFE. 
 
 more calcareous forms of the sea-mosses. As examples of the 
 former we may take the Graptolites, so named from their re- 
 semblance to lines of writing, and of which several forms 
 are represented in Fig. 37. The little teeth on the sides of 
 these were cells, inhabited probably by polyps, like those repre- 
 sented in the modern Sertularia in Fig. 36. Some of them 
 were probably attached to the bottom. In others the branches 
 radiated from a central film which may have been a hollow 
 
 FIG. 36. Group of modern Hydroids allied to Graptolites. Magnified, and natural sire. 
 a, Sertularia. b, Tubiilaria. c, Campanularia 
 
 vesicle or float, enabling them to live at the surface of the 
 water (Fig. 38). These Graptolites are specially character- 
 istic of the Upper Cambrian and Lower Silurian. The netted 
 ones (Dictyonemd), as may be seen from Figs. 34 and 35, came 
 in before the close of the Cambrian, and continue unchanged 
 to the Silurian, where they disappear. The branching forms, 
 seen in Fig. 37, have scarcely so great a range. They thus 
 form most certain marks of the period to which they belong, 
 
THE AGE OF INVERTEBRATES OF THE SEA. 55 
 
 and being oceanic and probably floaters, they diffused them- 
 selves so rapidly that they appear to indicate the same geological 
 time in countries so widely separated as Europe, North America, 
 
 FIG. 37. Silurian Graptolitidae. 
 
 a, Graptolithus. b, Diplograpsus. c, Phyllograpsus. d, Tetragrapsus. 
 e, Didyjnograpsus. 
 
 and Australia. It is curious, too, that while the Graptolites 
 thus mark a definite geological time, and seem to disappear 
 abruptly and without apparent cause, they are the first link in 
 the long chain of the Hydroids, which, though under different 
 
 FIG. 30. Ptibdictya ac-uta (Hall). Bryo- 
 zoan. Siluro-Cambrian. 
 
 FIG. 38. Central portion of Graptolite, 
 with membrane, or float (Dicho- 
 grapsus octobrachiatus, Hall). 
 
 family forms, continue to this day, apparently neither better nor 
 worse than their perished Palaeozoic relatives. There is a group of 
 little Stony Corals (Monticuliporida), which were possibly also 
 
THE CHAIN OF LIFE. 
 
 the cells of Hydroids, that have a similar history. They are 
 the only known Corals that date so far back as the Upper 
 Cambrian ; and they continue under very similar forms all 
 
 FIG. ypc.Fenestetta: Lye Hi (Dawson). A Carboniferous Bryozoart 
 
 through the Palaeozic, and are represented by the millepore 
 corals of the present day. Fig. 40 represents a form found at 
 the base of the Siluro-Cambrian, and Fig. 41 shows forms 
 characteristic of the Carboniferous Lime- 
 stone. 
 
 If we turn now to the sea-mosses (Bryozoa). 
 we have a group of minute polyp-like animals 
 inhabiting cells not unlike those of the Hy- 
 droids, and which form plant-like aggregates. 
 But the animals themselves are so different 
 in structure that they are considered to be 
 nearer allies of the bivalve shell-fishes than 
 of the Corals. They are, in short, so different, 
 that the most ardent evolutionist would 
 scarcely hold a community of origin between 
 them and such creatures as the Graptolites and 
 Millepores, though an ordinary observer might readily confound 
 the one with the other. These animals appear at the beginning 
 of the Siluro-Cambrian, and such forms as that represented in 
 
 FIG. 40 Chaetetes 
 fibrosa. A tubulate 
 coral with micro- 
 SQopic cells. Siluro- 
 Cambrian. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 57 
 
 Fig. 39, very closely allied to some now living, are large consti- 
 tuents of some of the limestones of that period. Other forms, 
 like that represented in Fig. 390, are very characteristic of the 
 Carboniferous. These animals, individually small, though com- 
 plicated in structure and branching into communities, scarcely 
 ever of any great magnitude, humble creatures which have 
 never played any great part in the world, have, nevertheless, 
 been so persistent that, though specific and generic forms have 
 been changed, the group may be said to be in the modern seas 
 exactly what it was in those of the early Palaeozoic, nor can it 
 be affirmed to have originated in anything different, or to have 
 produced anything. 
 
 FIG. 41. a, Stenopora e xilis (Dawson). 6, Chaetetes tumidus( Edwards and Haine). 
 Carboniferous. 
 
 The true Stony Corals (Anthozoa] are as yet unknown in the 
 Cambrian. They entered on the stage in immense abundance 
 in the Siluro-Cambrian, where considerable limestones are 
 largely composed of their remains, mixed, however, and some- 
 times overpowered with those of Bryozoa and Hydroids. An 
 ordinary coral, such as those of which coral reefs are built 
 the red coral, used for ornament is not quite similar is the 
 skeleton of an animal constructed on the plan of a sea anemone ; 
 with a central stomach surrounded by radiating chambers, and 
 having above a crown of tentacles. The stony coral sur- 
 rounds and protects the soft body of the animal, and may 
 either be a single cell, for one animal, or an aggregation of 
 
58 THE CHAIN OF LIFE. 
 
 such cells, .constituting a rounded or branching mass. The 
 modern star coral, represented in Fig. 42, is an instance of the 
 latter condition. It shows nineteen or twenty animals, each 
 with a central mouth and fringe of short tentacles, aggregated 
 together, and two of them showing the spontaneous division by 
 which the number of animals in the mass is progressively 
 increased. The living coral shows only the soft animals and 
 the animal matter connecting them ; but if dead there would 
 be a white stony mass with a star-like cell or depression 
 corresponding to each animal. 
 
 In their general plan, the oldest Corals were precisely of this 
 character, but they presented some differences in detail, which 
 have caused them to be divided into two groups, which are 
 
 FIG. 42. Living Antho2oan Coral (Astr&a}. 
 
 eminently characteristic of the Palaeozoic age the tabulate 
 or floored corals, and the rugose or wrinkled corals. In the 
 former (Fig. 43) the cells are usually small and thin- walled, 
 often hexagonal, like a honeycomb, and are floored across at 
 intervals with tabulae or horizontal plates. A few modern 
 corals present a similar arrangement, 1 but this kind of structure 
 was far more prevalent in the Palaeozoic. In the second type 
 the animals are usually larger and often solitary, the cell has 
 strongly marked radiating plates, while the horizontal floors 
 are absent or subordinate, and there is usually a thick exter- 
 nal rind or outer coat (Figs. 44, 45). In general plan, these 
 1 Ileliopora, an Alcyonarian ; Pccillopora, an Anthozoan. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 59 
 
 rugose corals closely resemble those of our modern reefs ; but 
 they differ in their details of structure, and only a very few 
 
 FIG. 43. Tabulate Corals. 
 a, Halisites* and b, Favosites, Upper Silurian. 
 
 modern forms from the deep sea are regarded as actual modern 
 representatives. 1 One curious point of difference is that their 
 
 FIG. 44. Rugose Coral (Heliophyllum Halli). Devonian. 
 
 radiating laminae begin with four, and increase by multiples of 
 that number, while in modern corals the numbers are six and 
 multiples of six ; a change of mathematical relation not easily 
 accounted for, and which assimilates them to Hydroids on the 
 
 1 Haflophyllia, Guynia, Duncania^ of Pourtales. 
 
6o 
 
 THE CHAIN OF LIFE. 
 
 one hand, and to a higher group, the Alcyonids, on the other, 
 both of which prefer four and eight to six, or have had these 
 numbers chosen for them. In the Mesozoic period the tabulate 
 and rugose corals were replaced by others, the porous and solid 
 
 FIG- 44#. Zaphrentis prolifica (Billings). Devonian. 
 
 corals of the modern seas ; but, in so far as we know, the 
 animals producing these, though differing in some details, were 
 neither more nor less elevated than their predecessors, and 
 they took up precisely the same role as reef-builders in the sea, 
 
 FIG. 45. Rugose Corals. 
 a, Zaphrentis Minos (Dn.), and b, Cyathophyllum Billingsi (Dn.). Carboniferous. 
 
 though with probably more tendency to the accumulation of 
 great masses of coral limestone in particular spots. 
 
 Leaving the corals, we may turn to the sea-stars and sea- 
 
THE AGE OF INVERTEBRATES OF THE SEA. 61 
 
 urchins. These merely put in an appearance in the Early 
 Cambrian, but become vastly multiplied in the Silurian, 
 where the stalked feather stars (Crinoids) (Fig. 46) seem to 
 have covered great areas of sea-bottom, and multiplied so 
 rapidly that thick sheets of limestone are largely made up of 
 
 FIG. 4 . Modern Crinoid (Rhizocrinus Lofotensis). After Sars. 
 
 the fragments of their skeletons. The ordinary star-fishes 
 appear first in the Silurian (Fig. 47). The sea-urchins begin 
 in the Upper Silurian, the early species having numerous and 
 loosely attached plates, like some of those now found in the 
 deep sea l (Fig. 48). 
 
 1 Pal&chinus. 
 
62 THE CHAIN OF LIFE. 
 
 The most curious history in this group is that of the feather- 
 stars. In the Early Cambrian they are represented by a few 
 species known to us only in fragments, and these belong to a 
 humble group (Cystideans) resembling the larval or immature 
 condition of the higher Crinoids. Fig, 49 shows one of these 
 animals of somewhat later age. They have few or rudimentary 
 arms and short stalks, and want the beautiful radial symmetry 
 of the typical star-fishes. In the Silurian these creatures are 
 reinforced by a vast number of beautiful and perfect feather- 
 stars (Figs. 50, 51). These continue to increase in number 
 and beauty, and apparently culminate in the Mesozoic, where 
 gigantic forms exist, some of them probably having more 
 
 FIG. 47. Pal&aster Niagarensis FIG. 48. Palcechinus ellipticus (McCoy). 
 
 (Hall). One of the oldest star fishes. One of the oldest types of sea-urchins. 
 
 complicated skeletons, in so far as number of distinct parts is 
 concerned, than any other animals. Buckland has calculated 
 that in a crinoid similar to that in Fig. 52 there are no less 
 than 150,000 little bones, and 300,000 contractile bundles of 
 fibres to move them. In the modern seas the feather-stars 
 have somewhat dwindled both in numbers and complexity, 
 and are mostly confined to the depths of the ocean. On the 
 other hand, the various types of ordinary star-fishes and sea- 
 urchins have increased in number and importance. We thus 
 find in this group a certain advance and improvement from the 
 Cystideans of the Early Palaeozoic to the sea-urchins and their 
 allies. This advance is not, however, along one line for the 
 
-THE AGE OF INVERTEBRATES OF THE SEA. 63 
 
 Cystideans continue unimproved to the end. The Crinoids 
 culminate in the Mesozoic, and are not known to give origin to 
 anything higher. The star-fishes and sea-urchins commence 
 independently, before the culmination of the Crinoids, and, 
 though greatly increased in number and variety, still adhere 
 very closely to their original types. 
 
 Fis. 49. Pleurocystites FIG. 50. Heterocrinus FIG. 51. Body of Glypto- 
 
 squamosus. Siluro-Cam- simplex (Meek). One of crz'nus. Siluro-Cambrian. 
 
 brian. After Billings. the least complex crinoids 
 
 of that period. Siluro- 
 Cambrian. 
 
 The great sub -kingdom of the Mollusca, including the bivalve 
 and univalve shell-fishes, makes its first appearance in the 
 Cambrian, where its earliest representatives belong to a group, 
 the Arm-bearers or Lamp shells (Brachiopods), held by some to 
 be allied to worms as much as to mollusks. The oldest of all 
 these shells are allies of the modern Lingulcz (Fig. 54), some of 
 
6 4 
 
 THE CHAIN OF LIFE. 
 
 the earliest of which are shown in Fig. 55. The modern Lin- 
 gula is protected by a delicate two-valved shell, composed, 
 unlike that of most other mollusks, of phosphate of lime or 
 bone earth. It lives on sand-banks, attached by its long 
 flexible stalk, which it buries like a root in the bottom. Its 
 food consists of microscopic organisms, drifted to its mouth 
 by cilia placed on two arm-like processes, from which the group 
 derives its name. In the modern world about one hundred 
 
 FIG. 52. Extracrinus Briarens. 
 Reduced. Jurassic. 
 
 FIG. 53. P entacrinns caput-inedii 
 Reduced. Modern. 
 
 species of Brachiopods are known, belonging to about twenty 
 genera, some of which differ considerably from the Lingulse. 
 The genus Terebratula, represented at Fig. 56, is one of the 
 most common modern as well as fossil forms, and has the 
 valves unequal, with a round opening in one of them for the 
 stalk, which is attached to some hard object, and there is an 
 internal shelly loop for supporting the arms. 
 
-THE AGE OF INVERTEBRATES OF THE SEA. 65 
 
 These curious, and in the modern seas, exceptional shells, 
 were dominant in the Palaeozoic period. Upwards of three 
 thousand fossil species are known, of which a large proportion 
 belong to the Cambrian and Silurian, nine genera appearing 
 in the Cambrian, and no less than fifty-two in the Silurian. The 
 history of these creatures is very remarkable. The Lingulae, 
 which are the first to appear, continue unchanged and with the 
 same phosphatic shells to the present day. Morse, who has 
 
 FIG. 54. Lingula anatina. 
 With flexible muscular 
 stalk. Modern. 
 
 FIG- 55. Cambrian and Silurian Lingulae. a> 
 Lingiilella Matthewi (Hartt). Acadian group* 
 
 b, Lingula, quadrata (Hall). Siluro-Cambrian, 
 
 c, Lingulella prima (Hail). Potsdam. </, 
 Lingulella antiqua (Hall). Potsdam. 
 
 carefully studied an American species, remarks in illustration of 
 this, that it is exceedingly tenacious of life, bearing much change 
 of depth, temperature, etc., without being destroyed. The genus 
 Discing which is nearly as old, also continues throughout geo- 
 logical time. The genus Orthis (Fig. 57), which appears at the 
 same time with the last, becomes vastly abundant in Silurian 
 times, but dies out altogether before the end of the Palaeozoic. 
 Rhynchonella (Fig. 58), which comes in a little later, near the 
 
66 
 
 THE CHAIN OF LIFE. 
 
 beginning of the Siluro-Cambrian, continues to this day. Spirifer 
 and Productus (Figs. 59 and 60) appear later, and die out at 
 
 FIG. 56. Terebratnla sacculus (Martin). Carboniferous. 
 
 the close of the Palaeozoic. So strange and inscrutable are 
 the fortunes of these animals, which on the whole have lost in 
 
 FIG. 57. Erachiopods; genus Orthis. 
 
 a, O. Bittingsi (Hartt). Lower Cambrian, b, O. pectinella (Hall). Siluro-Cambrian. 
 c, O. lynx (Eichwald). Siluro-Cambrian. 
 
 the battle of life, that their place in nature is vastly less 
 important than it was. It has been suggested that if any group 
 
 FIG. 58. Rhynchonella.increbrescens(R-a\\). Siluro-Cambrian. 
 
 of creatures could throw light upon the theory of descent with 
 modification, it would be these ; but Davidson, who has per- 
 haps studied them more thoroughly than any other naturalist, 
 
THE AGE OF INVERTEBRATES OF THE SEA. 67 
 
 found them as silent on the subject as the sponges or the 
 corals. In a series of papers published in the Geological 
 Magazine, a short time before his death, he remarked as 
 follows : 
 
 "We find that the large number of genera made their, first 
 
 FIG. 59. Spirifer mucronatus (Conrad). Devonian. 
 
 appearance during the Palaeozoic periods, and since they have 
 been decreasing in number to the present period. We will 
 leave out of question the species, for they vary so little that it 
 is often very difficult to trace really good distinctive characters 
 between them ; it is different with the genera, as they are, or 
 
 FIG. 59.2. Athyris j#/zYa (Hall). Carboniferous. 
 <z, b, Exteriors, c, Interior, showing spirals. 
 
 should be, founded on much greater and more permanent dis- 
 tinctions. Thus, for example, the family Spiriferidce includes 
 genera which are all characterised by a calcified spiral lamina 
 for the support of the brachial appendages ; and, however varied 
 these may be, they always retain the distinctive characters of 
 the group from their first appearance to their extinction. The 
 
 F 2 
 
68 THE CHAIN OF LIFE. 
 
 Brachiopodist labours under the difficulties of not .being able to 
 determine what are the simplest, or which are the highest 
 families into which either of the two great groups of his 
 favourite class is divided ; so far, then, he is unable to point out 
 any evidence favouring progressive development in it. But, 
 confining himself to species, he sees often before him great 
 varietal changes, so much so as to make it difficult for him to 
 define the species ; and it leads him to the belief that such 
 groups were not of independent origin, as was universally 
 thought before Darwin published his great work on the Origin 
 of Species. But in this respect the Brachiopoda reveal nothing 
 more than other groups of the organic kingdoms. 
 
 FIG. 60. Productus cora (D'Orbigny). Carboniferous. 
 
 " Now, although certain genera, such as Terebratula, Rhynchon- 
 ella. Crania, and Discina, have enjoyed a very considerable 
 geological existence, there are genera, such as Stringocephalus, 
 Uncites, Porambonites, Koninckina, and several others, which 
 made their appearance very suddenly and without any warning ; 
 after a while they disappeared in a similar abrupt manner, 
 having enjoyed a comparatively short existence. They are all 
 possessed of such marked and distinctive internal characters 
 that we cannot trace between them and associated or synchron- 
 ous genera any evidence of their being either modifications of 
 one or the other, or of being the result of descent with modifi- 
 cation. Therefore, although far from denying the possibility 
 or probability of the correctness of the Darwinian theory, I 
 could not conscientiously affirm that the Brachiopoda, as far as 
 
THE AGE OF INVERTEBRATES OF THE SEA. 69 
 
 I am at present acquainted with them, would be of much ser- 
 vice in proving it. The subject is worthy of the continued 
 and serious attention of every well-informed man of science. 
 The sublime Creator of the universe has bestowed on him a 
 thinking mind ; therefore all that can be discovered is legitimate. 
 Science has this advantage, that it is continually on the advance, 
 and is ever ready to correct its errors when fresh light or new 
 
 FIG. 61. Group of Older Palaeozoic Lamellibranchs. After Billings- 
 
 i, Citciillea opitna. 2, Nucnla oblonga. 3, N-ucula linfata. 4, Cypricardia truncata. 
 5, Tellina ovata. 6, hvcula bellatula. 7, Modiola concentrica. 
 
 discoveries make such necessary." The late Joachim Barrande, 
 the great palaeontologist of Bohemia, bears similar testimony. 
 
 The ordinary bivalves, like the mussels and cockles, now so 
 very plentiful on our coasts, are rare in the Cambrian and Silu- 
 rian, and for the first time make a somewhat conspicuous 
 appearance in the Upper Silurian and Devonian. But from 
 the first they resemble very closely their modern successors, 
 though on the whole neither so large nor so ornate (Fig. 61). 
 Their fortunes have thus been precisely the opposite of those of 
 
70 THE CHAIN OF LIFE. 
 
 the Brachiopods, though in neither case is there very marked 
 elevation or deterioration in the individual animals. A very 
 similar statement may be made as to the sea-snails, whether the 
 curious winged snails (Pteropods) or the ordinary crawlers (Gas- 
 
 FIG. 62. Comtlaria planicostata (Dn.)- A Carboniferous Pteropod. 
 
 tropods). The former come in early, and are represented by 
 Palaeozoic forms finer than any now extant. The genus Conulana 
 (Fig. 62) presents some Silurian species six inches or more 
 in length, which are giants in comparison with any now 
 
 FIG. 63. Silurian Sea-snails. Canada. 
 
 a, Miirchisonia bicincta (Hall), b, Pleurotoittaria itinlilicatula (Hall), c, Miirchisonia 
 gracilis (Hall), d, Bellerophon sulcatinus (Billings). 
 
 living. The forms of more ordinary Gastropods from the 
 Silurian represented in Fig. 63 will suffice to show that their 
 styles are not very dissimilar from those still extant. 1 As in 
 
 1 Some of the earliest appear to be allies of the modern limpets. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 71 
 
 the case of the ordinary bivalves, however, the modern Gas- 
 tropods much exceed in numbers and magnitude those of the 
 Palaeozoic. 
 
 The highest group of Mollusks, represented in the modern 
 ocean by the Nautili and Cuttle-fishes, has a history so strange 
 and eventful, and so different from what might have been 
 anticipated, that it perhaps deserves a more detailed notice, 
 more especially as Barrande has recently directed marked 
 attention to it in his magnificent work on the Palaeontology 
 of Bohemia. 
 
 The Cuttle-fishes and Squids and their allies are, in the 
 modern seas, a most important group (Fig. 64). The great 
 numbers in which the smaller species appear on many coasts, 
 and the immense size and formidable character of others ; 
 their singular apparatus of arms, bearing suckers, their strange 
 forms, and the inky secretion with which they can darken the 
 water, have at all times attracted popular attention. The 
 great complexity of their structures, and the fact that in many 
 points they stand quite at the head of the invertebrates of the 
 sea, and approach most nearly to the elevation of the true 
 fishes, have secured to them the attention of naturalists. Some 
 of these animals have shelly internal supports, and one genus, 
 that of the Argonauts, or Paper Nautili, has an external pro- 
 tective shell. Allied, though more distantly, to the Cuttle- 
 fishes, are the true Nautili, represented in the modern sea 
 principally by the Pearly Nautilus, though there are two other 
 species, both of them very rare. The modern pearly nautilus 
 (Fig. 65) may be regarded as a peculiar kind of cuttle-fish 
 provided with a discoidal shell for protection, and also for 
 floatage. The shell is divided into a number of chambers 
 by partitions. Of these the animal inhabits the last and 
 largest. The others are empty, and are connected with the 
 body of the animal only by a pipe, or siphuncle, with mem- 
 branous walls and filled with fluid. Thus provided, the 
 nautilus, when in the water, has practically no weight, and can 
 
72 
 
 THE CHAIN OF LIFE. 
 
 move up or down in the sea with the greatest facility, using 
 its sucker-bearing arms and horny beak to seize and devour 
 the animals on which it preys. The buoyancy of the shell 
 seems exactly adapted to the weight of the animal ; and this 
 proportion is kept up by the addition of new air-chambers as 
 the body increases in size. In the modern seas this singular 
 little group stands entirely isolated, and its individuals are 
 so rare that it is difficult to procure perfect specimens for 
 
 FIG. 64. Squid (Lotigd). FIG. 65. Pearly Nautilus (Naittilus pompilius). 
 
 a, Mantle. l>, Its dorsal fold. c, Hood. 
 o, Eye. t, Tentacles, f, Funnel, g, Air 
 chambers. ^, Siphuncle. 
 
 collections, though its mechanical structure and advantages 
 for the struggle for existence seem of the highest order. But 
 in the old world of past geological time the case was 
 altogether different. 
 
 The Nautiloid shell-fishes burst suddenly upon us in the 
 beginning of the Siluro-Cambrian, or Lower Silurian, Barrande's 
 second fauna ; and this applies to all the countries where 
 
THE AGE OF INVERTEBRATES OF THE SEA. 73 
 
 they have been studied. In this formation alone about 450 
 species are known, and in the Silurian these increase to 1,200 ; 
 and here the group culminates. It returns in the Devonian to 
 about the same number with the Lower Silurian, diminishes 
 in the Carboniferous to 350, and in the Mesozoic, where 
 the Nautiloid forms are replaced by others of the type 
 
 FIG. 67. Gomphocer^s. 
 
 FI-.J. 66.Orthoceras. Siluro-Cam- 
 brian. The dotted line shows the 
 position of the siphuncle. 
 
 FIG. *8>.Lituites. 
 
 of the Ammonites, becomes largely reduced. In the Tertiary 
 there are but nineteen species, and, as already stated, in 
 the modern world three. These statements do not, however, re- 
 present the whole truth. In the Palaeozoic, in additon to the 
 genus Nautilus, we have a great number of other genera, some 
 with perfectly straight shells, like Orthoceras (Fig. 66), others 
 
74 
 
 THE CHAIN OF LIFE. 
 
 bent (Cyrtoceras), others differing in the style of siphuncle, 
 or aperture, or chambers (EndocertR^ Gomphoceras, Lituites> 
 
 FIG. 69. Nautilus Avonensis (Dn.). Carboniferous. 
 a, Shell, reduced, b, Section, showing siphuncle. 
 
 Figs. 67 to 69), or inflated into sac-like forms (Ascoceras). There 
 is, besides, the family of the Goniatida (Fig. 70), with the 
 
 FIG. 70. Goniatites crenistria (Philips). Carboniferous. 
 
 chambers thrown into angular folds and the siphuncle at the 
 back. 'Further, some of the early forms, as the Orthoceratidae, 
 
THE AGE OF INVERTEBRATES OF THE SEA. 75 
 
 attain to gigantic dimensions, being six feet or more in length, 
 and nearly a foot in diameter. Thus the idea that we should 
 naturally form from the study of the Nautilus, that it represents 
 a type suited for much more varied and important adaptations 
 than those that we now see, is more than realised in those 
 Palaeozoic ages when these animals seem to have been the 
 lords of the seas. 
 
 When we leave the Palaeozoic and enter the Mesozoic, though 
 the Nautiloid shells still abound, we find them superseded, in 
 great part, by a nobler form, that of the Ammonitidce (Figs. 7 1, 
 
 FIG. 71. Ceratites nodosus (Schloth). Triassic. 
 
 72). These are remarkable for the ornate markings on the 
 surfaces of their shells, and for the beautifully waved edges of 
 the partitions (Fig. 720), which, by giving a much more com- 
 plete support to the sides of the shell, must have contributed 
 greatly to the union of lightness and strength so important to the 
 utility of the shell as a float This type admits of all the same 
 variety of straight, bent, and curled forms with the simpler 
 Nautiloid type, and some of the species are of great size, Am- 
 monites being known three feet or more in diameter. These 
 animals, unknown in the Palaeozoic, appear in numerous species 
 
7 6 
 
 THE CHAIN OF LIFE. 
 
 in the Early Mesozoic, culminate in hundreds of beautiful species 
 in the middle of that era, and disappear for ever at its close, 
 leaving no modern successors. Many and beautiful species of 
 Ammonites and their allies have been obtained from the 
 
 FIG. 72. Ammonites Jason (Reinecke). Jurassic. 
 
 Mesozoic rocks of British Columbia and other parts of the 
 west coast of North America, perfectly representing this group 
 as it occurs at the same period in Europe, and closely resembling 
 
 FIG. jza. Suture of Ammonites componens (Meek), of British Columbia. Showing 
 the complicated folding of tbe edges of the chambers to give strength to the shell. 
 Cretaceous. 
 
 the Mesozoic Ammonites of India. These animals have all 
 perished, yet the Atlantic and the Pacific roll between, apparently 
 with conditions as favourable for their comfortable existence as 
 those of any previous time. They perished long ago, at the 
 
- THE AGE OF INVERTEBRATES OF THE SEA. 77 
 
 dawn of the Tertiary ; yet the genus Nautilus, one of the oldest 
 and least improved of the whole, survived, and still testifies to 
 the wonderful contrivance embodied in these animals. 
 
 These are merely general considerations, but Barrande, in his 
 Etudes Generates, goes much farther. He sums up all the known 
 facts in the most elaborate manner, considering first the em- 
 bryonic characters of the shell in the different genera, then their 
 
 FIG. 73. Cretaceous Ammonitidae. 
 a, Baculites. b, Ancyloceras. c, Crioceras. d, Turrilites. 
 
 distribution in space and time, then all the different parts and 
 characters of the shells in the different groups the whole with 
 reference to any possible derivation of the species ; and he 
 finds that all leads to the result that in every respect these 
 shells seem to have been so introduced as to make any theory 
 of evolution with respect to them altogether untenable. In his 
 concluding sentence this greatest of Palaeozoic palaeontologists 
 
78 THE CHAIN OF LIFE. 
 
 affirms that, "The theoretical evolution of the Cephalopods 
 is, like that of the Trilobites, a mere figment of imagination, 
 without any foundation in fact." 1 
 
 I have reserved no space to notice the geological history of 
 the other and higher group of Cephalopods, including the true 
 Cuttles and Squids. This is perhaps less to be regretted, as, 
 from the absence of external shells, they are likely to be much 
 
 FIG. 74. Belemnite. After Philips. 
 
 less perfectly known as fossils. So far as known, they are 
 vastly younger than the Nautiloids, for no examples whatever 
 have been found in the Palaeozoic. They appear abundantly in 
 
 FIG. 74. Belemnoteuthis antiquus. Supposed to be a Belemnite, with soft parts 
 preserved. Jurassic. After Mantell. 
 
 the Mesozoic, but are there represented principally by an 
 extinct group of squids (Belemnites and their allies, Figs. 74, 
 74<z), remarkable for the great and complicated development of 
 their internal support, which has a chambered float as well as a 
 solid sheath. This family becomes extinct at the close of the 
 
 1 " Un produit de 1'imagination, sans aucun fondement dans la realite." 
 
THE AGE OF INVERTEBRATES OF THE SEA. 79 
 
 Mesozoic, though the cuttles as a whole perhaps culminate in 
 the modern. 
 
 The remarkable group of the Trilobites had precedence in 
 order of time of the Nautiloid shell-fishes. No animal structures 
 can well be more dissimilar than those of the two great groups 
 of aquatic animals which popular speech confounds under the 
 name of " shell-fishes." Take a whelk and a crab, for example, 
 and compare their general forms, the structure of their shells, 
 arid their organs of motion, and it is scarcely possible to imagine 
 any two animals more unlike; and when we examine their 
 
 
 FIG. 75. Cambrian Trilobites. 
 
 a, Paradoxides. b, Dikellocephalus. c t Conocoryphe (head), d, Agnostus (head 
 
 and tail). 
 
 anatomy in detail this difference does not diminish. They have, 
 it is true, corresponding parts, and these parts serve similar 
 uses, but in plan of structure they are wholly different. Yet 
 both animals may live in the same pool, and may subsist on 
 nearly the same food. If we attempt to find some common 
 type which both resemble, we may trace the structure of the 
 crab back to those of some of the marine worms with which it 
 has some affinity, and those of the whelk to such creatures as 
 the Lingula, which are supposed to have a resemblance to 
 
8o 
 
 THE CHAIN OF LIFE. 
 
 the worms. But still the two types, that of the Mollusk and 
 the Articulate, are distinct even from their first appearance in 
 the egg, nor have either any close affinities with the Protozoa, 
 the Hydroids, or the Corals. 
 
 Both types meet us in the Early Cambrian, but while the 
 Mollusk is there represented only by low forms, the Articulate 
 is then not only in the humble guise of the worm, but in the 
 complex and highly organised form of the Trilobite (Figs. 28 
 and 75). What older phases they may have passed through we 
 
 FIG. 76. 'Transverse section of Calymene. A Silurian Trilobite. After Wolcott. 
 
 Dorsal shell. b, Visceral cavity, c, Legs. d, Epipodite gill-cleaner or palp. 
 e, Spiral gills. 
 
 know not ; but in the Lower Cambrian we have various forms 
 of these animals, including some of the largest known as well 
 as some of the smallest ; some of the most complex in num- 
 ber of parts as well as some of the simplest. These animals, 
 in short, seem to have appeared at once all over the world 
 fully formed, and in a variety of generic and specific forms ; and 
 nothing short of a very large faith in the imperfection of the 
 geological record can suffice to account for their evolution. 
 A Trilobite is a creature in whose structure the number three 
 
-THE AGE OF INVERTEBRATES OF THE SEA. 81 
 
 is dominant. Seen from above, it presents three divisions from 
 front to rear : first, a cephalic shield or head-piece ; secondly, 
 a thorax, divided into several segments ^movable upon each 
 other ; and thirdly, a tail-piece or pygidium, which, when brought 
 against the head by the rolling up of the body segments, effec- 
 tually covers the lower parts. This lower portion was until 
 
 FIG. 7 6a.~ Burrows of Trilobite and of modern King-crab. The Trilobite burrow is 
 vn as Kuschmites, and has been supposed to be a sea-weed of the kind called Bilobites. 
 
 lately little known ; but the discoveries of Billings and of 
 Wolcott have enabled us to restore the jaws under the head, 
 the jointed legs and spiral gills under the thorax, and thus to 
 complete the structure of the animal, and understand better its 
 relations to modern crabs and shrimps (Fig. 76). Of these it 
 certainly comes nearest to the King-crabs and Horseshoe-crabs, 
 
 G 
 
82 
 
 THE CHAIN OF LIFE. 
 
 a somewhat limited group at present, and one which reaches 
 back in geological time only to the Upper Silurian, when the 
 Trilobites had perhaps already passed their culmination. 
 
 Constructed as above described, the Trilobite could swim, as 
 is supposed, usually on its back or side. It could crawl on the 
 bottom. Using its snout as a shovel, it could burrow like a 
 modern King-crab (Fig. 760) .; and when pressed by danger some 
 species could roll themselves into balls and defy their enemies. 
 
 FIG. 77. Silurian Trilobites. 
 a, Isotelus. b, Homalonotus. c, Calymene. 
 
 This type of animal, entering on the stage in full force in 
 the Older Cambrian, continues under many forms through the 
 whole Palaeozoic age, dying out finally in the Carboniferous. 
 Figs. 77 and 78 show a few of the forms of the Silurian, 
 Devonian, and Carboniferous. 
 
 Contemporaneously with the dawn of the Trilobite group, 
 
 appear some small shrimp-like forms (Fig. 28), 1 and others 
 
 with bivalve shells (Fig. 79), which are closely allied to modern 
 
 forms, 2 and, like the Lingultz, persist through the succeeding 
 
 1 Hymenocaris. 2 Phyllopods and Ostracods. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 83 
 
 formations with little more than specific change presenting in 
 this a strange contrast to the Trilobites. While the latter were 
 
 FIG. 78. Devonian and Carboniferous Trilobites. 
 a, Phaceps latifrons (Bronn). b, Philipsia Howi (Billings) (tail). 
 
 still flourishing, about the close of the Lower Silurian, a 
 remarkable group of large and highly-developed creatures, 
 
 FIG. 79. Palaeozoic Ostracod Crustaceans. Magnified. 
 
 a,Bairdi b, Cytherella inflate (Jones), c, Cythere. Carboniferous, d, Beyrichia 
 Jvneszi (Dn.). Carboniferous, e, Beyrichia pustulosa (&*\\\ Silurian. 
 
 allied to the Trilobites, but suited for rapid swimming rather 
 than creeping, was introduced ; and in the Upper Silurian and 
 
 G 2 
 
84 THE CHAIN OF LIFE. 
 
 Devonian these creatures l attained to gigantic sizes, exceeding, 
 probably, any modern Crustaceans, and were tyrants of the 
 seas. Pterygotus anglicus (Fig. 80) is supposed to have attained 
 the length of six feet. Yet these noble representatives of 
 the Crustaceans became extinct in the Carboniferous. On 
 the other hand, a few small king-crabs appear in the Upper 
 Silurian, and this type still continues, and seems to culminate 
 as to size in modern times ; so diverse have been the fortunes 
 of these various groups. 
 
 The higher, or decapod Crustaceans, now familiar to us in 
 the modern crabs and lobsters, are first found in a few small 
 
 FIG. 80. Pterygotus anglicus. Reduced. After Page and Woodward. 
 
 species in the Devonian 2 and Carboniferous, and they are 
 accompanied in the Devonian by at least one species of the 
 allied group of the Stomapods (Figs. 81, 82). 
 
 The Palaeozoic age of geology is thus emphatically an age 
 of invertebrates of the sea. In this period they were dominant 
 in the waters, and until toward its close almost without rivals. 
 We shall find, however, that in the Upper Silurian, fishes made 
 their appearance, and in the Carboniferous amphibian reptiles, 
 and that, before the close of the Palaeozoic, vertebrate life in 
 1 Pterygotus, Eurypterus, &c. 2 Whitfield, Am. Journ. ofSci., 1880. 
 
THE AGE OF INVERTEBRATES OF THE SEA. 85 
 
 these forms had become predominant. We shall also see that 
 just as the leading groups of Mollusks and Crustaceans seem 
 to have had no ancestors, so it is with the groups of 
 Vertebrates which take their places. It is also interesting to 
 observe that already in the Palaeozoic all the types of inverte- 
 brate marine life were as fully represented as at present, and 
 that this swarming marine life breaks upon us in successive 
 waves as we proceed upward from the Cambrian. Thus the 
 progress of life is not gradual, but intermittent, and consists in 
 the sudden and rapid influx of new forms destined to increase 
 
 FIG. 81. A vtphipeltis paradoxus (Salter). FIG. 82. Anthropaltemon Hilliana 
 
 A Devonian Stomapod from New (Dn). A Carboniferous Decapod 
 
 Brunswick. from Nova Scotia. The carapace 
 
 only. 
 
 and multiply in the place of those which are becoming effete 
 and ready to vanish away or to sink to a lower place. Farther, 
 since the great waves of aquatic life roll in with each great 
 subsidence of the land, a fact which coincides with their 
 appearance in the limestones of the successive periods, it 
 follows that it is not struggle for existence, but expansion under 
 favourable circumstances and the opening up of new fields of 
 migration that is favourable to the introduction of new species. 
 The testimony of palaeontology on this point, which I have 
 
86 THE CHAIN OF LIFE. 
 
 elsewhere adduced at length, 1 in my judgment altogether 
 subverts the prevalent theory of " survival of the fittest," and 
 shows that the struggle for existence, so far from being a cause 
 of development and improvement, has led only to decay and 
 extinction, whereas the advent of new and favourable condi- 
 tions, and the removal of severe competition, are the circum- 
 stances favourable to introduction of new and advanced 
 species. This testimony of the invertebrates of the sea we 
 shall find is confirmed by other groups of living beings, to be 
 noticed in the sequel. 2 
 
 1 Report on Devonian Fossil Plants of Canada, 1871. Story of the 
 Earth and Man, 1873. Address to American Association, 1875. 
 
 2 See the important memoir of Barrande on the Silurian Brachiopods, in 
 which, as the result of the most elaborate and detailed comparisons, he 
 concludes that in the case of these shells, as in that of the Cephalopods and 
 Trilobites, the introduction of species in geological time has not occurred 
 by modification, but must have depended on a creative process. It is such 
 painstaking researches as those of the great Bohemian palaeontologist which 
 must finally settle these questions, in so far as geology is concerned. 
 
 NOTE. The term " Siluro-Cambrian," as used in this and the next 
 chapter, is synonymous with "Ordovician" of Lapworth, which is now 
 coming into somewhat general use. 
 
CORDAITES, OF THE GROUP OF DORY-CORDAITES. BRANCH RESTORED. 
 After Grand' Eury. 
 
CHAPTER IV. 
 
 THE ORIGIN OF PLANT LIFE ON THE LAND. 
 
 IF the graphite of the Laurentian rocks was derived from 
 vegetable matter, the further question arises, Was this vege- 
 tation of the land, or of the sea ? and something may be said on 
 both sides of this question. If there were land plants in the 
 Laurentian period, they must have grown either on rocks older 
 than the Laurentian itself, or on such portions of the beds of 
 the latter as had been raised out of the sea, forming perhaps 
 swampy flats of newly-made soil. But we know no rocks older 
 than the Laurentian, and there is no positive evidence that any 
 of the beds of that formation were other than marine. Still 
 it is not impossible that some of the beds which are now graphitic 
 gneisses may originally have been similar to the bituminous 
 shales, coals, or underclays of the coal formation. The graphite 
 occurring in veins, if of vegetable origin, must have been 
 derived from liquid bitumen oozing into fissures ; and veins of 
 this kind occur in later formations, both in marine and fresh- 
 water beds. The only other positive argument which has been 
 adduced in favour. of the existence of abundant land plants 
 in the Laurentian is that of Dr. Sterry Hunt, derived from 
 the great beds of iron ore, which it is difficult to account 
 for chemically except on the hypothesis of the decay in the air 
 of great quantities of vegetable matter. The question must 
 remain in doubt till some one is fortunate enough to find 
 
90 THE CHAIN OF LIFE. 
 
 portions of the Laurentian carbon retaining traces of organic 
 structure. My own observations, though somewhat numerous, 
 allow me only to say that the graphite sometimes presents 
 fibrous forms, that it occasionally appears as vermicular threads 
 which, however, I suppose to be fillings of canals of Eozoon 
 and that_in the graphitic beds there are occasionally slender 
 root-like bodies of a lighter colour than the mass ; but none of 
 these indications are sufficient to determine anything as to its 
 vegetable origin, or the nature of the plants from which it may 
 have been derived. 
 
 In any case, the quantity of carbon which has been accumu- 
 lated in the Laurentian rocks is very great. I have measured 
 one bed at Buckingham, on the Ottawa, estimated to contain 
 20 per cent, of carbon, and which is at least eight feet in 
 thickness. Sir William Logan has described another similar 
 bed from ten to twelve feet thick, and more recent reports of 
 the Geological Survey of Canada mention a bed supposed to 
 be twenty-five feet thick, in which Mr. Hoffman finds 30 
 per cent, of carbon. On the whole the quantity of carbon in 
 the graphitic zone of the Laurentian is comparable with that 
 in certain productive coal-fields, and we certainly have in the 
 subsequent geological history no examples of such accumu- 
 lations except from remains of the luxuriant vegetation of 
 swampy flats. 
 
 The Upper Laurentian and Huronian have as yet afforded 
 no evidence of land vegetation. The Cambrian, as already 
 stated, abounds in remains of sea-weeds ; but though the forms 
 which have been named Eophyton have been regarded as land 
 plants, this claim is, to say the least, very doubtful ; and I have 
 as yet seen nothing of this kind which did not appear to me to 
 be merely markings made by objects drifted over the bottom 
 or remains of marine plants. Yet in the Upper Cambrian there 
 are wide surfaces of littoral sandstone often containing minute 
 carbonised fragments, and which might be expected to afford 
 indications of land vegetation, had such existed. I have myself 
 
-THE ORIGIN OF PLANT LIFE ON THE LAND. 91 
 
 devoted many days of fruitless labour to the examination of the 
 large areas of Potsdam sandstone exposed in some parts of 
 Canada. But as these rocks were evidently formed along the 
 borders of a Laurentian continent capable of supporting 
 vegetation, we may still hope for some discovery of this kind, 
 
 FIG. 83. Protannularia Harknessii (Nicholson). A Siluro-Cambrian Plant, from the 
 Skiddaw series. 
 
 more especially if we could find the point where some fresh- 
 water stream ran into the Cambrian sea. 
 
 The oldest plants, probably higher than Algae, known to me 
 by their external forms, are those described by Nicholson * from 
 the Siluro-Cambrian Skiddaw slates of the north of England 
 1 Geological Magazine, November, 1869. 
 
92 THE CHAIN OF LIFE. 
 
 (Fig. 83). Their discoverer has named them Buthotrephis Hark- 
 nessii and B. radiata? stating, however, that these two species 
 are not improbably portions of the same plant, and that its 
 form is rather that of a land plant than of an Alga. The 
 specimens of these plants which I have seen appear to me to 
 support the conclusion that they represent one species, and 
 this allied to the Annularies of the Devonian and Carboniferous 
 periods, which probably grew in shallow water with only their 
 upper parts in the air, and bore whorls or verticles of narrow 
 
 FIG. 84. American Lower Silurian Plants. After Lesquereux. 
 Sphenophylhim pritntevum. b, Protostigma sigillarioides. 
 
 leaves. They were either relatives of the Mare's-tails, or 
 of the Rhosocarps, of our modern swamps and ponds. 
 
 Somewhat higher up in the Lower Silurian, in the Cincin- 
 nati group of America, Lesquereux finds objects which he 
 
 1 The genus Butholrephis includes supposed branching sea-weeds of the 
 Silurian. For this reason I would propose the name Protannularia for 
 these plants. 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 93 
 
 refers to the genus Sphenophyllum, which is closely allied to 
 Annularia (Fig. 84, a\ and also a plant which he terms 
 Protostigma (Fig. 84, b\ and believes to be the stem of a 
 tree allied to the club-mosses. 1 He also finds minute branch- 
 ing stems, which he refers to the genus Psilophyton, to be 
 mentioned in the sequel ; but as to these I have some doubts 
 whether they may not be Zoophytes allied to the Graptolites, 
 rather than plants of that genus. These discoveries tend to 
 show the probable existence in the Siluro-Cambrian of plants 
 representing two of the three leading families of the higher 
 cryptogams or flowerless plants, namely, the Club-mosses and 
 the Mare's-tails. Thus land vegetation begins with the highest 
 
 
 yj 
 
 FIG. 86. Fragment of outer surface of Glyptodendron of Claypole. A 
 Silurian Tree. 
 
 members of the lower of the two great series into which 
 botanists divide the vegetable kingdom. 
 
 If we now turn to the Silurian, further evidence of land 
 vegetation presents itself. Near the base of this great 
 series, the club-moss family is represented by a plant discovered 
 by Claypole in the Clinton group, and referred to a new genus 
 (Glyptodendron^ Fig. 86). Plants of this family have also been 
 noticed by Barrande in Bohemia, and by page in Scotland ; 
 and a humble but interesting member of the family, connecting 
 
 1 Lycopodiacetz. 
 
94 THE CHAIN OF LIFE. 
 
 it with the pillworts, Psilophyton (Fig. 87), though more cha- 
 racteristic of the Devonian, has been found in the Upper 
 Silurian both in Canada and the United States. No Ferns 
 or Equiseta have as yet been found in the Silurian ; but in 
 1870 I recognised in some fragments of wood from the Ludlow 
 bone-bed, in the Museum of the Geological Survey of Great 
 Britain, the structure of that curious prototypal tree, to which I 
 have given the name Nematophyton, and which was first recog- 
 nised in the Devonian of Gaspe. Since that time I have 
 found in the Upper Silurian beds of Cape Bon Ami, in New 
 Brunswick, similar fragments of fossil wood, associated with 
 round seed-like bodies, having a central nucleus and a thick 
 wall or test of radiating fibres. These bodies show a structure 
 similar to that of those found in the Upper Ludlow of 
 England, and described by Hooker under the name Pachytheca. 
 In my judgment they are certainly true seeds. 1 Seeds of this kind 
 have also been found by Hicks in the still older Denbighshire 
 grits of North Wales, along with fragments of the wood of 
 Nematophyton, and with remains of branching stems which have 
 been described under the name Berwynia, though it is not 
 unlikely that they represent the branches of Nematophyton. It 
 is proper to add that these ancient vegetable fossils are re- 
 garded by some English botanists as gigantic algae or sea-weeds, 
 but I confess I am unable to adopt this view of their nature. 
 The supposed fern of the Upper Silurian, figured in the 
 first edition of this work, has proved on further examination 
 to be merely an imitative form produced by crystallisation. 
 On the other hand, the recent discovery of a cockroach 
 and two species of Scorpion in the Silurian, proves the 
 existence of land animals as well as plants at this period. 
 
 It is probable that these discoveries represent merely a 
 small proportion of the plants actually existing in the 
 Silurian period. All the deposits of this age at present known 
 
 1 Allied to those named by Brongniart Aetheotesta. 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 95 
 
 to us are marine ; and most of them were probably formed at 
 a distance from land, so that it is little likely that land plants 
 
 FIG. 87. Psilofhyton princess (T)n.). Silurian and Devonian. Restored. 
 
 a, Fruit, natural size, b, Stem, natural size, c, Scalariform tissue of the axis, highly 
 
 magnified. In the restoration one side is represented in vernation, and the other in fruit. 
 
96 THE CHAIN OF LIFE. 
 
 could find their way into them. At any time the discovery of 
 an estuarine or lacustrine deposit of Silurian age might wonder- 
 fully extend our knowledge of this ancient flora. 
 
 The Devonian or Erian age, that of the classic Old Red 
 Sandstone of Scotland, is that in which we find the first great 
 and complete land flora ; and though this is inferior in number 
 of species to that of the succeeding Carboniferous, and greatly 
 less important with reference to its practical bearing on our 
 welfare, it is in some respects superior in that variety which 
 depends on diversity of soil and of station. To appreciate 
 this, it will be necessary to glance at the range and subdivisions 
 of the modern flora. 
 
 In the modern world we divide all vegetation into two great 
 series, that of the Flowering Plants (Phcenogams), which also 
 produce true fruits and seeds, and that of the Flowerless 
 Plants (Cryptogams), which produce minute spores instead of 
 seeds. The latter is in every respect the lower group. This 
 lower series is again divisible into three classes first and 
 lowest, that of the Seaweeds, Moulds, and Lichens (Thall- 
 ophytes). Secondly, that of the Mosses and their allies 
 (Anophytes). Thirdly, that of the Ferns, Equisetums and 
 Club-mosses (Acrogens). In like manner the second, or 
 higher series is divisible into three classes : that of the Pines 
 and Cycads (Gymnosperms), having naked seeds not covered 
 by true fruits, and woody tissue of simple structure ; that of 
 the Palms and Grasses and their allies (Endogens) ; and last 
 and highest, that of the ordinary timber trees and other plants 
 allied to them, with exogenous stems, netted-veined leaves, and 
 a two-leaved embryo (Exogens). These last are in every 
 respect the dominant plants on our present continents. 
 Carrying with us this twofold division of the vegetable 
 kingdom and its subdivisions, we shall be prepared to under- 
 stand the relation of the more ancient floras to that now 
 living. 
 
 In the Devonian age we meet with no land plants of the two 
 
-THE ORIGIN OF PLANT LIFE ON THE LAND. 97 
 
 lower classes of the Cryptogams, and with scarcely any that can 
 be referred to the two higher classes of Phaenogams, so that 
 the vegetation of this period presents a remarkable character 
 of mediocrity, being composed almost entirely of the highest 
 class of the flowerless plants and the lowest class of those that 
 flower. Of the former there are Tree-ferns and vast numbers of 
 herbaceous forms (Figs. 88, 89), great Lycopodiaceous plants, 
 
 FIG. 88. Trunk of a Devonian Tree-fem (Caulopteris Lockwoodi, Dn.). Gilboa, 
 New York. One-third natural size. 
 
 immensely better developed than those now existing (Fig. 90), 
 and gigantic Calamites, allied to the Mares'-tails (Fig. 91), 
 along with humbler members of the same group (Fig. 95). Of 
 the latter there were Pines of great stature, known to us at 
 present only by their wood (Fig. 92) ; and that other allied 
 trees existed we have evidence in numerous seeds which 
 must have belonged to this class (Fig. 93), and in long flag- 
 
9 8 
 
 THE CHAIN OF LIFE. 
 
 like leaves l which modern discoveries would refer to the same 
 group. As yet we know no Devonian Palms or Grasses ; and 
 
 FIG. 89. Frond of A rchceopteris Jacksoni (Dn.). Devonian, of Maine. 
 
 only a single specimen has been found indicating the existence 
 
 FIG. 9 o.-Portion of a branch of Le^hleum rhombicum (Dn ) A Lycopodiaceous 
 tree of the Devonian of Maine. Natural size. 
 
 of a plant of the highest vegetable class, that of the true 
 
 1 Cordaites, 
 
' THE ORIGIN OF PLANT LIFE ON THE LAND. 99 
 
 exogens. This unique specimen, found by Hall in the 
 Devonian of the shores of Lake Erie, is a fragment of 
 mineralised wood, the structures of which are represented in 
 Fig. 94. The large ducts seen in cross section in Nos. i, 2, 
 
 FIG. 91. Calamites radiatus (Brongniart). Middle Devonian of N. Brunswick. 
 
 and 3, and in longitudinal section in Nos. 4 and 5, and the 
 medullary rays, seen in Nos. i, 4, and 6, testify to the fact that 
 this chip of wood must have belonged to a tree of the same 
 type which contains our oaks, maples, and poplars; a type 
 
 H 2 
 
IOO 
 
 THE CHAIN OF LIFE. 
 
 which does not appear to have become dominant till near the 
 close of the Mesozoic, but which already existed, though 
 
 FIG. 92. A Devonian Taxine Conifer (Dadoxylpn ouangondianum, Dn.)- St. John, 
 New Brunswick. 
 
 A Fragment showing Sternbergia pith and wood ; a, Medullary sheath ; b, Pith ; 
 
 c, Wood ; d, Section of pith. 
 B, Wood cell a, and hexagonal areole and pore b. 
 
 c, Longitudinal section of wood, showing a, Areolation, and b, Medullary rays. 
 D, Transverse section showing a, Wood-cells, and b, Limit of layer of growth. 
 
 perhaps only in few species, and only in upland and inland 
 positions, as far back as the Middle Devonian. Perhaps one of 
 the most interesting discoveries in the Erian or Devonian 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 101 
 
 rocks has been that of the immense abundance of spores of 
 those humble plants the Rhizocarps, represented in modern 
 times by the Pillworts and Salviniae, &c. To these it is believed 
 that Sphenophyllum and Psilophyton were allied ; but in 
 
 FIG. 93. Group of Devonian Fruits, &c. Middle Devonian, New Brunswick. 
 
 A, Cardiocarpum comutum. 
 
 B, Cardiocarpum acutum. 
 
 C, Cardiocarpum Crampii. 
 
 D, Cardiocarpum Barleyi. 
 
 E, Trigonocarpum racemosum. 
 E 1 , E 2 , Fruits enlarged. 
 
 F, Antholithes Devonicus. 
 F 1 , Fruit of the same. 
 
 G, Annularia acuminata. 
 
 H, Asterophyllites acicularis. H 1 . Leaf. 
 K, Cardiocarpum. (? young of A.) 
 L, Pinnularia dispalans. 
 
 From Acadian Geology. 
 
 addition to this there are thick and vastly extended beds of 
 bituminous shale which owe their inflammable properties to 
 countless multitudes of Macrospores (Sporangites) of the genus 
 Protosalvinia}- In Ohio there are beds of this kind 350 feet thick, 
 and extending across the State. They occur also in Canada, where 
 1 Paper by Sir W. Dawson in Chicago Academy's Bulletin, 1886. 
 
102 
 
 THE CHAIN OF LIFE. 
 
 these forms were first recognised by the writer in the 
 bituminous shale of Kettle Point, Lake Huron. 
 
 The Devonian flora seems to have been introduced in the 
 northern parts of the American continent at a time of warm 
 and equable climate, and of elevation of new land- out of 
 the Silurian sea. It spread itself to the southward, and was 
 
 JIG. 94. Structures of the oldest-known Angiospermous Exogen (Syringoxylon 
 mirabile, Dn.). From Eighteen-mile Creek, Lake Erie. 
 
 i, Transverse section X 100. 2 and 3, Portions of the same X 300. 4, Longitudinal 
 section X 300. 5, Fragment of duct from the same X 600. 6, Wood cells and 
 medullary ray x 600. 
 
 finally destroyed in the great subsidences and disturbances 
 which closed the Devonian age, and which were probably 
 accompanied with refrigeration of climate. It was succeeded 
 by the more massive and richer, but more monotonous flora 
 of the Carboniferous, a period in which large areas of our 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 103 
 
 continents were in the state of swampy and often submerged 
 flats, and in which the climate was again warm and uniform. 
 
 The Carboniferous age was, even more emphatically than the 
 Devonian, an age of Acrogens and Conifers. A few Carboni- 
 ferous Fungi have recently been discovered, but there are no 
 known Lichens or Mosses. There seem to be a few Endogens, 
 but no true Exogens. The great bulk of the plants consists of 
 
 i 
 
 FIG. 95. Asterophyllites pmvula (Dn.), and Sphtnnphyllum antiquum (Dn ). 
 Middle Devonian, New Brunswick. 
 
 Acrogens and Gymnosperms, as in the previous period. As 
 this flora is so very important and so much better known than 
 any other of those belonging to the infancy of the vegetable 
 kingdom, we may notice a little in detail some of its leading 
 forms. 
 
 Beginning with the Mares'-tails, we find these represented in 
 the Carboniferous by many gigantic species, attaining to almost 
 
FIG. 96. Calamites. Carboniferous. 
 
 A. C- Siicko-vii. B, C. Cistii(Rt.). c, Base of Calamites. D, E, Structures. 
 
 From Acadian Geology, 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 105 
 
 tree-like dimensions (Fig. 96). These are the Calamites, which 
 formed dense brakes and jungles on the margins of the great 
 swampy flats of this period. Their tall stems, ribbed and 
 jointed, bore whorls of leaves or branchlets. Sending out 
 horizontal root-stocks and budding out from the base, they 
 grew in great clumps, and had the capacity to resist the effects 
 
 "/ 
 
 
 FIG. 97. Carboniferous Ferns. 
 
 A, Odontopteris subcuneata (Bunbury). B, Neuropteris cordata (Brongniart). 
 c, Alethopteris tonchitica (Brongniart). 
 
 of accumulating sediment by constantly sending out new stems 
 at higher and higher levels. The larger species assumed a 
 complexity in the structure of their stems unknown in their 
 modern congeners, and enabling them to grow to a great 
 height ;* but their foliage and fructification were not correspond- 
 ingly advanced. Thus the family of the Equisetaceae culminated 
 
 1 Calamcdendron and Arthrofitys are forms of ihis kind. 
 
io6 THE CHAIN OF LIFE. 
 
 in the Carboniferous, and thenceforth descended gradually in 
 the succeeding ages, leaving the comparatively humble Mares'- 
 tails and Scouring Rushes as its present representatives. 
 
 The Ferns of the Carboniferous, like those of the Devonian, 
 presented both gigantic forms like those of the tree-ferns of 
 the modern tropics, and delicate herbaceous species, and these 
 in great profusion. On the whole, they do not strike the 
 observer as very dissimilar from those of modern times. A 
 more critical examination, however, shows that the bulk of the 
 tree-ferns of the Devonian and Carboniferous are allied not 
 to the Polypod type, which is the most common at present, 
 but to certain comparatively rare southern ferns, the Marattias 
 and their allies, characterised by a peculiar style of fructifica- 
 tion, perhaps adapting them to a moist and warm atmosphere 
 (Fig. 97). 1 Thus the ferns, while a wonderfully persistent type, 
 were in their grander forms far more widely distributed in the 
 Carboniferous than at present ; and genera now comparatively 
 rare, and limited to warm and moist climates, were then abun- 
 dant, and ranged over those temperate and boreal regions of 
 the Northern Hemisphere where only a few humble and hardy 
 species can now subsist. There were also some remarkable 
 and anomalous tree-ferns, of which that represented in Fig. 98 
 is an example. 
 
 The family of the Club-mosses, already, even in the Devonian, 
 in advance of its modern development, experiences in the Car- 
 boniferous a remarkable and portentous extension into great 
 trees of several genera and many species, constituting apparently 
 extensive forests, and having the woody tissues of their stems 
 developed to a degree unheard of in their present representatives 
 (Fig. 99). Further, they become closely linked, in external form 
 at least, with another and more advanced type, that of the 
 Sigilfaria. These remarkable trees were the most abundant 
 of all in the swamps of the coal-formation, and probably those 
 
 1 Grand' Eury and Williamson have directed attention to this in the case 
 of those of France and England. 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 107 
 
 which most contributed to the accumulation of coal. They 
 presented tall pillar-like trunks, often ribbed longitudinally, and 
 with perpendicular rows of scars of fallen leaves. Dividing at 
 top into a few thick branches, they were covered with long 
 rigid grass-like foliage. Their fruit was borne in rings or 
 
 FIG. 08. Carboniferous Tree-ferns. 
 
 A, Megaphyton inagnificum (Dn.). c, Palceopteris Hartii (Dn.). 
 D, P. Acadica (Dn.). 
 
 whorls of spikes surrounding the branches at intervals (Fig. 
 100). Their roots were strangely symmetrical, spreading out 
 like underground branches into the soft soil by a regular pro- 
 cess of bifurcation, and were covered with rootlets diverging 
 in every direction, and so jointed to the main root that when 
 broken off they left round marks regularly arranged. These 
 
io8 
 
 THE CHAIN OF LIFE. 
 
 FIG. 99. Lepidodendron corr-ugatnm (Dn.). A characteristic Lycopod of the Lower 
 Carboniferous of America. 
 
 A, Restoration. B, Leaf, natural size, c, Cone. D. Leafy branch. E, Forms of 
 leaf-bases. F, Sporangium. I, L, M, N, o, Markings on stem and branches, in 
 vanous states. 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 109 
 
 FIG. 100. SigillaricE of the Carboniferous. 
 
 A, Sigillaria Brou>nit (Dn..). B, S. elegans (Brongniart). B 1 , &c. Leaf and 
 Leaf-scars. 
 
i io THE CHAIN OF LIFE. 
 
 roots are the so-called Stigmarice, so abundant in every coal-field, 
 and especially filling the " under-clays" of the coal-beds, which 
 are the soils on which the plants forming these beds were sup- 
 ported. The true botanical position of the Sigillaria has been 
 a matter of much controversy. Some of them undoubtedly 
 have structures akin to those of the tree-like Club-mosses, as 
 Williamson has well shown, and may have been cryptogamous. 
 Others have structures of higher character, akin to those of the 
 modern Cycads, and seem to have borne nutlets allied to 
 those of these plants. Yet the external forms of these diverse 
 sorts are so similar that no definite separation of them has 
 yet been made. Either these anomalous trees constitute a 
 link connecting the two great series of the vegetable kingdom, 
 or we have been confounding two distinct groups, owing to 
 imperfect information. 
 
 Another curious, and till recently little understood, group 
 of Carboniferous trees is that known as Cordaites, which 
 existed already in some of its species in the Devonian. Their 
 leaves are long, and often broad as well, and with numerous 
 delicate parallel veins, resembling in this the leaves of grasses. 
 Corda long ago showed that one species at least has a stem 
 allied to the Club-mosses. More recently Grand' Eury has 
 found in the South of France admirably preserved specimens, 
 which show that others more resembled in their structure the 
 Pines and Yews, and were probably Gymnosperms, approaching 
 to the Pines, but with very peculiar and exceptional foliage, of 
 which the only modern examples are the broad-leaved Pines of 
 the genus Dammara (Frontispiece to Chapter). Here again 
 we have either two very distinct groups, combined through 
 our ignorance, or a connecting link between the Lycopods and 
 the Pines. 
 
 The Yews and their allies among modern trees, while mem- 
 bers of the great Cone-bearing order, bear nut-like seeds in 
 fleshy envelopes, sometimes, as in the Ginkgo of Japan, consti- 
 tuting edible fruits. Seeds of this type seem to have been 
 
THE ORIGIN OF PLANT LIFE ON THE LAND, ill 
 
 extremely abundant in the Carboniferous age in all parts of 
 the world, and were probably produced by trees of several 
 genera (Dadoxylon, Sigillaria^ Cordaites, etc.) (Fig. 101). 
 Charles Brongniart has recently described no less than seven- 
 teen genera of these seeds from the coal-field of St. Etienne 
 alone, and it would be a low estimate to say that we probably 
 
 FIG. 101. Trigonocarpum Hookeri (Dn.). A Gymnospermous seed. 
 a, Testa, b, Tegmen. c, Nucleus, d, Embryo. 
 
 know as many as sixty or seventy species in all, while the 
 trunks of great coniferous trees allied to Taxineae, and 
 showing well-preserved structure, are by no means uncommon 
 in the Devonian and Carboniferous. Had these great Yews 
 appeared for the first time in the Coal-formation, we might have 
 supposed that they had been developed from such Lycopods 
 as Lepidodendra, and that the Cordaites are the intermediate 
 
112 THE CHAIN OF LIFE. 
 
 forms ; but unfortunately the Pines go almost as far back in 
 geological time as the Lycopods, and it does not help us, when 
 in search of evidence of evolution, to find the link which is 
 missing or imperfect in the Early Devonian supplied in the 
 Coal-formation, where, for this purpose at least, it is no longer 
 needed. 
 
 We have said something of what was in the Palaeozoic flora ; 
 but what of that which was not ? We may answer : Nearly 
 all that is characteristic of our modern forests, whether in the 
 ordinary Exogens, which predominate so greatly in the trees and 
 shrubs of temperate climates, or in the Palms and their allies, 
 which figure so conspicuously within the tropics. The few rare, 
 and to some extent doubtful, representatives of these types 
 scarcely deserve to be noted as exceptions. Had a botanist 
 searched the Palaeozoic forests for precursors of the future, he 
 would probably have found only a few rare species, while he 
 would have seen all around him the giant forms and peculiar 
 and monotonous foliage of tribes now degraded in magnitude 
 and structure, and of small account in the system of nature. 
 
 It must not be supposed that the Palaeozoic flora remained in 
 undisturbed possession of the continents during the whole of 
 that long period. In the successive subsidences of the conti- 
 nental plateaux, in which the marine limestones were de- 
 posited, it was to a great extent swept away, or was restricted 
 to limited insular areas, and these more especially in the far 
 north, so that on re-elevation of the land it was always peopled 
 with northern plants. Thus there were alternate restrictions 
 and expansions of vegetation, and the latter were always 
 signalised by the introduction of new species, for here, as 
 elsewhere, it was not struggle, but opportunity, that favoured 
 improvement. 
 
 In the Lower Silurian such plants as existed must have ex- 
 perienced great restriction at the age of the Niagara or Wen- 
 lock limestone. Those of the Upper Silurian suffered a similar 
 reverse at the time of the Lower Helderberg or Ludlow lime- 
 
THE ORIGIN OF PLANT LIFE ON THE LAND. 113 
 
 stones. This recurred at the close of the Devonian and in 
 the time of the Lower Carboniferous limestone ; and finally the 
 Palaeozoic flora disappeared altogether in the Permian, to be 
 replaced by new types in the Mesozoic. While, therefore, there 
 is a great general similarity in the successive Palaeozoic floras, 
 there are minor differences, so that the Devonian plants are for 
 the most part distinct specifically from those of the Lower Car- 
 boniferous, those of the Lower Carboniferous from those of 
 the Coal-formation, and those of the latter from those of the 
 Permian. 
 
 With all these vicissitudes it is to be observed that there is 
 no apparent elevation of type in all the long ages from the 
 Devonian to the Permian, that the Acrogens and Gymnosperms 
 of these periods are in some respects superior, in all respects 
 equal, to their modern successors, and that their history shows 
 a decadence toward the modern period ; that intermediate 
 forms arrive too late to form connecting links in time, that 
 several distinct types appear together at the beginning, and 
 that all utterly and apparently simultaneously perish at the end 
 of the Palaeozoic, to make way for the entirely new vegetation 
 of the succeeding age. Theories of evolution receive no 
 support from facts like these, though their practical signifi- 
 cance, as parts of the one great uniform scheme of nature, is 
 sufficiently manifest. 
 
 Of what use then were these old floras? To the naturalist, 
 vegetable life, with regard to its modern uses, is the great 
 accumulator of pabulum for the sustenance of the higher 
 forms of vital energy manifested in the animal. In the Palae- 
 ozoic this consideration sinks in importance. In the Coal 
 period we know few land animals, and these not vegetable 
 feeders, with the exception of some insects, millipedes, and 
 snails. But the Carboniferous forests did not live in vain, if 
 their only use was to store up the light and heat of those old 
 summers in the form of coal, and to remove the excess of 
 carbonic acid from the atmosphere. In the Devonian period 
 
114 THE CHAIN OF LIFE. 
 
 even these utilities fail, for coal does not seem to have been 
 accumulated to any great extent, and the petroleum of the 
 Devonian appears to have been produced from aquatic vege- 
 tation. Even with reference to theories of evolution, there seems 
 no necessity for the long continuance and frequent changes of 
 species of acrogenous plants without any perceptible elevation. 
 We may have much yet to learn of the life of the Devonian ; 
 but for the present the great plan of vegetable nature goes 
 beyond our measures of utility ; and there remains only what 
 is perhaps the most wonderful and suggestive correlation of 
 all, namely, that our minds, made in the image of the Creator, 
 are able to trace in these perished organisms structures 
 similar to those of modern plants, and thus to reproduce in 
 imagination the forms and habits of growth of living things 
 which so long preceded us on the earth. We may indeed 
 proceed a step further, and hold that, independently of human 
 appreciation, these primitive plants commended themselves to 
 the approval of their Maker, and perhaps of higher intelli- 
 gences unknown to us ; and that in the last resort it was for 
 His pleasure that they were created. 
 
1 
 
CHAPTER V. 
 
 THE APPEARANCE OF VERTEBRATE ANIMALS. 
 
 /^"CONFESSEDLY the highest style of animal is that which 
 \^s possesses a skull and backbone, with brain and nerve 
 system to match, and which embodies the general plan of 
 structure employed in man himself. Yet among the fishes, 
 which constitute the lowest manifestation of this type, are 
 some so rudimentary that the brain is scarcely developed, and 
 the skeleton is merely a cord of gristle. These are represented 
 in the modern world only by the Lancelot, 1 a creature which 
 has sometimes been mistaken for a worm, and by a slightly 
 more advanced type, that of the Lampreys. 2 In these animals 
 the Vertebrates make the nearest approach to the lower 
 domains of the animal kingdom, collectively known as Inverte- 
 brates. We should naturally expect that since the vertebrates 
 succeed the inferior animals in time, their lower types should 
 appear first, and that these should be aquatic rather than 
 terrestrial. On the other hand, as the oldest fishes that are 
 certainly known ' are strongly protected with bony armour, 
 and had to contend against formidable Crustaceans and Cuttles, 
 we might suppose that the Lancelot and the Lampreys are 
 rather degraded types belonging to the modern period, than 
 the true precursors of the other fishes. 
 
 1 Amph^o.\^ts. 2 Fetromyzon, &c. 
 
Ii8 THE CHAIN OF LIFE. 
 
 But if fishes like the Lancelot preceded all others, we may 
 never find in a fossil state any traces of their soft and perish- 
 able bodies ; and even the Lampreys have no hard parts except 
 small horny teeth, which might easily escape observation. But 
 palaeontologists have sharp eyes, and it has not escaped them 
 that certain microscopic tooth-like bodies are somewhat widely 
 distributed in the older rocks. In Russia, Pander has found 
 in the Upper Cambrian and Lower Silurian, and also in the 
 Devonian and Carboniferous, minute conical and comb like 
 
 FIG. 102. Siluro-Cambrian Conodonts. Magnified. After Pander. 
 
 teeth, to which he has given the name of Conodonts (Fig. 102), 
 and which he supposes to be the teeth of ancient Lampreys. 
 Similar teeth have been found by Moore and others in the 
 Carboniferous of England, and by Newberry in Carboniferous 
 shales in Ohio. In point of form, these bodies certainly re- 
 semble the teeth of the humble fishes to which they have been 
 referred. In the case of the Carboniferous specimens from 
 Ohio the only ones I have had an opportunity to examine 
 
APPEARANCE OF VERTEBRATE ANIMALS. 119 
 
 the material is calcium phosphate, and the structures are more 
 like those of teeth of Sharks than of Lampreys, so that there 
 can be no doubt that they are really teeth of fishes, and pro- 
 bably of fishes of somewhat higher grade than the Lampreys. 1 
 The Cambrian and Silurian specimens are said to be composed 
 of calcium carbonate, which would render it more probable that, 
 as has been suggested by Prof. Owen, they may have been teeth 
 of some species of Sea-snail destitute of shell. It is, however, 
 possible that they may have originally been horny, and that the 
 animal matter has been replaced by carbonate of lime. 
 Rohon and Zittel have recently shown that many of these 
 are more allied to the teeth of worms than of any other 
 animals. 2 
 
 FIG. 103. Lower Carboniferous Conodont. Magnified. After Newberry. 
 
 If these older Conodonts were really teeth of fishes, they carry 
 the introduction of these nearly as far back as that of the 
 Mollusks and Crustaceans. If they were not, then the earliest 
 known representatives of this class belong to a much later 
 age, that of the Silurian. Here we have undoubted remains 
 of fishes belonging to two of the higher orders of the class ; 
 and in the succeeding Devonian these became multiplied and 
 extended exceedingly. 
 
 1 Dr. Newberry has kindly furnished me with specimens, and Dr. Har- 
 rington has submitted to analysis portions of shale filled with these little 
 teeth, the result giving 2'$& of calcium phosphate for the whole, which 
 indicates that the Conodonts are really bone. Their microscopic structure 
 approaches to that of the dentine of such Carboniferous fishes as Diplodus. 
 Hinde has described Conodonts from the Silurian of Canada. 
 
 2 Ueber Conodont en \ Munich, 1886. 
 
120 THE CHAIN OF LIFE. 
 
 Besides the inferior tribes already referred to, the modern 
 seas and rivers present four leading types of fishes : first, the 
 ordinary bony fishes (Teleostians), such as the Cod, Salmon, 
 and Herring ; secondly, the Ganoid fishes, protected with bony 
 plates on the skin, as the Bony-pike 1 and Sturgeon ; thirdly, the 
 Sharks and their allies, the Dog-fishes and Rays : fourthly, the 
 peculiar and at present rare group of semi-reptilian fishes to 
 which the name of Dipnoi has been given, on account of their 
 capacity for breathing both in air and in water. 
 
 Of these four types the first is altogether modern, and 
 includes the great majority of our present fishes. It does not 
 make its appearance till the Cretaceous age, and then is at 
 once represented by at least three of the modern families, those 
 of the Salmon, Herring, and Perch. The history of the other 
 three groups is precisely the opposite of this. They abound 
 exceedingly at an early period, and dwindle to a much smaller 
 number in the modern time. This is especially the case with 
 the Ganoids and the Dipnoi. It is also remarkable that these 
 groups of old-fashioned fishes 2 are in some respects the highest 
 members of the class, approaching the nearest to the reptiles ; 
 but this accords with a well-known palaeontological law, namely, 
 that the higher members of low groups give way on the intro- 
 duction of more elevated types, while the lower members may 
 continue. Thus the decadence of these higher fish begins with 
 the incoming of the reptiles, just as the decadence of the higher 
 Mollusks and predaceous Crustaceans began with the incoming 
 of the fishes. Further, the modern Ganoids and Dipnoi are 
 mostly fresh-water animals, though the Sharks are largely pelagic. 
 In the Palaeozoic there seem to have been abundance of marine 
 species of all these types ; but though marine, they probably 
 flourished most in bays and estuaries and on shallow banks ; 
 and the existence of these implies continental masses of land. 
 This explains the curious coincidence that the introduction 
 of fishes and of an abundant land flora synchronise, and 
 1 Lepidosteus. * Palceichthyes of Giinther. 
 
APPEARANCE OF VERTEBRATE ANIMALS. 121 
 
 that the ocean was still dominated by Invertebrates long 
 after the fishes had become supreme in bays, estuaries, and 
 rivers. 
 
 The first fishes that we certainly know are the Ganoids and 
 Sharks, which appear near the close of the Upper Silurian, in 
 the English Ludlow for example (Fig. 104). The Ganoids found 
 here all belong to an extinct group, characterised by the covering 
 of the head and anterior part of the body with large bony 
 plates. They are mostly small fishes, and probably fed at the 
 bottom, and used their long or rounded bony snouts for 
 
 FIG- 104. a, Head shield of an Upper Silurian fish (CyatJtaspis). 6, Spine of a Silurian 
 Shark (Onchus tenui-striatus, Agass.). c, d, Scales of Thecodus, enlarged. 
 
 grubbing in the mud for food. In this respect they present 
 a singular resemblance to the Trilobites, so that we seem to 
 have here animals of an entirely new type, the Vertebrate, and 
 with bony instead of shelly coverings, taking up the role and, 
 to some extent, the external form of a group about to pass away. 
 Yet I presume that no derivationist would be hardy enough to 
 affirm that the Trilobites could have been the ancestors of 
 these fishes. Nor indeed is any ancestry even hypothetically 
 known for them, for the doubtful Lampreys of the Cambrian 
 Silurian are too remote and uncertain to be used in that way. 
 
122 THE CHAIN OF LIFE. 
 
 The head-shield copied in outline in Fig. 104, and the restora- 
 tion after Lankester in the frontispiece to this chapter, may 
 serve to represent these curious primitive Ganoids, which are 
 continued in the Devonian fishes represented in Figs. 105, 106. 
 Along with these, and not improbably their enemies, were 
 certain Sharks (Fig. 104), known to us only by the spines which 
 
 FIG. 105, Cephalaspis Dawsoni (Lankester). Lower Devonian of Gaspe. 
 
 were attached to their fins as weapons of defence, and by 
 detached bony tubercles which protected their skin. These 
 remains are chiefly interesting as indications that two of the 
 great leading divisions of the class of fishes originated together. 
 In the Devonian age the Ganoids and Sharks, thus introduced 
 in the Silurian, may be said to culminate. The former, more 
 
APPEARANCE OF VERTEBRATE ANIMALS. 123 
 
 especially, are represented by a great variety of species, some 
 of them nearly allied to their Silurian predecessors (Fig. 106), 
 others of forms and structure not dissimilar to those of the few 
 surviving representatives of the order, or altogether peculiar to 
 the Devonian (Fig. 107). So numerous are these fishes, and 
 of so many genera and species and this not merely in one 
 region, but in widely separated parts of the world that the 
 Devonian has not inaptly been called the reign of Ganoids. 
 
 FIG. 106. Devonian Placoganoid Fishes (Pterichthys comutus, Cephalaspis Lyelli), 
 from Scotland. 
 
 As an illustration at once of the very peculiar forms of some 
 of these fishes and of their wide distribution, I figure here along 
 with the British species a Cephalaspis (Fig. 105) found in the 
 Lower Devonian of Gaspe, in the same beds with some of the 
 antique Devonian plants described in the last chapter. 
 
 A new and interesting light has recently been cast upon some 
 of the most anomalous of the ancient fishes by the study of 
 the now rare and peculiar species of the group of Dipnoi. 
 Two of these, belonging to the genus Lepidosiren, are the 
 
124 
 
 THE CHAIN OF LIFE. 
 
 " Mud-fishes " of the rivers of tropical Africa and America (Fig. 
 1 08, b.) These creatures have an elongated and elegant form, 
 
 FIG. 107. Devonian Lepidoganoid Fishes (Diplacanthus and Osteolepis). After Page 
 and Nicholson. 
 
 and the body is covered with overlapping horny scales like those 
 of ordinary fishes ; but the pectoral and ventral fins are rod-like, 
 
 FIG. 108. Modern Dipnoi. 
 a, Ceratodus Fosteri. Australia, b, Lepido&iren annectus. Africa. 
 
 and are supported by simple cartilaginous rays, while the tail- 
 fin forms a fringe around the posterior part of the body., 
 
APPEARANCE OF VERTEBRATE ANIMALS. 125 
 
 Unlike ordinary fishes, they have lungs as well as gills, and 
 their mouths are armed with sharp, bony, beak-like teeth (Fig. 
 115), with which they can inflict terrible bites on the small 
 fishes and frogs which furnish them with food. Their most 
 remarkable habit is that of burying themselves in the mud of 
 dried-up ponds, thus forming a sort of water-chamber or 
 " cocoon," in which they remain in a torpid state until the 
 return of the rainy season sets them free. 
 
 Another example of these Dipnoi is the Barramunda, or 
 Ceratodus of the Australian rivers (Fig. 1080). This fish re- 
 sembles the Lepidosiren in many essential points of structure ; 
 
 FIG. 109. Anterior part of the palate of Dipterus. Showing the dental plates at 
 Devonian. After Traqoair. 
 
 but its fins have lateral rays, and are consequently of some 
 breadth, though of peculiar form, and its mouth is armed 
 with flat, pavement-like teeth, wherewith it browses on aquatic 
 grasses. 
 
 These modern fishes have enabled us to understand several 
 mysterious forms met with in the older rocks. In the first 
 place, they show the meaning of certain flat-toothed fishes, like 
 Dipterus of the Devonian (Fig. 109), Conchodus of the Car- 
 boniferous (Fig. no), and Ceratodus of the Carboniferous and 
 Trias (Figs, in, 112), previously of very doubtful character. 
 These must all have been of similar structure and habits with 
 
126 THE CHAIN OF LIFE. 
 
 the Barramunda, which is thus the sole survivor, perhaps itself 
 verging on extinction, of a group of herbivorous fishes introduced, 
 it may be, contemporaneously with the first stream affording 
 the requisite vegetable food, and which have continued almost 
 without improvement or deterioration to the present time. 
 
 FIG. no. Dental plate of Conchodus plicatus (Dn.). Coal-formation of Nova Scotia. 
 Acadian Geology. 
 
 These fishes are, however, very closely connected with the 
 Ganoids, and there are some of these, with fringed fins and 
 overlapping scales, which, while regarded as true Ganoids, 
 resemble the Dipnoi very closely. 
 
 FIG. in. Dental plate of Ceratodus Barrandii. Coal-formation of Bohemia. 
 After Fritsch. 
 
 Again, certain huge fishes, whose remains are found in the 
 Devonian of Ohio, 1 had jaws on the same plan with those of 
 Lepidosiren, but of enormous size and strength (Figs. 113, 114, 
 1 Dinichthys Terrelli and Z>. Hertzeri (Newberry). 
 
APPEARANCE OF VERTEBRATE ANIMALS. 127 
 
 115), so that in this and some other points of structure they 
 may be regarded as colossal Mud-fishes, and they must have 
 
 FIG. ii2. Dental plate of Ceratodus serratus. From the Trias. 
 
 had the same destructive powers, but on a far grander scale. 
 They were besides clothed with heavy armour of bony scales, 
 having some resemblance to that of those mailed fishes of 
 
 FIG. 113. Jaws of D;nichthys Hertzeri (Newberry). Laterally compressed ; 
 one-sixth natural size. 
 
 smaller size already referred to, and indicating that, huge 
 though they were, and formidable in destructive power, they 
 
128 THE CHAIN OF LIFE. 
 
 also had enemies to be dreaded. These plates serve to ally 
 them with the Ganoids, as their jaws do with Lepidosiren. 
 
 We are thus enabled to see in the streams, lakes, and bays 
 of the Palaeozoic, harmless fishes, of the type of Ceratodus, 
 feeding on plants, and huge precursors of the Mud-fishes 
 
 FIG. 114. Lower Jaw of Dinichthys Htrtzeri, One-sixth natural size. 
 
 darting from the depths, and provided with a dental apparatus 
 more formidable than that of any modern fish, sufficient to 
 pierce the strongest armour of the Ganoids, and to destroy and 
 devour the largest aquatic animals. These huge fishes, armed 
 with shears two or three feet in length, and capable of cutting 
 
 FIG. 115. Jaws of Lepidosiren. Natural size. After Newberry. 
 
 asunder scale, flesh, and bone, are the beau ideal of destructive 
 monsters of the deep, far surpassing our modern Sharks ; and 
 if, by means of supplementary lungs, they could breathe in air 
 as well as in water, they would on that account be all the more 
 vigorous and voracious. 
 
APPEARANCE OF VERTEBRATE ANIMALS. 129 
 
 Newberry has well remarked that while in the Devonian the 
 Ganoids and Dipnoi were the real tyrants of the sea, as well 
 as of the streams, in the Carboniferous they already diminish 
 in size, though still abundant as to numbers, and are more 
 limited to estuaries and fresh waters. Thus their departure 
 from power had already begun, and went on until in modern 
 times the proportion of Ganoids to ordinary fishes is, according 
 to Giinther, nine out of 9,000. The Carboniferous, indeed, 
 very specially abounds in small Ganoids, though there are many 
 large and formidable species. One of these smaller species, a 
 
 FIG. 116. A small Carboniferous Ganoid (Pal&oniscns (Rhadinichthys) Modulus' 
 Dn.). Lower Carboniferous, New Brunswick, a. Outline, b, c, d, Sculpture of scales' 
 
 magnified. 
 
 very beautiful little fish, of fresh-water ponds and streams in 
 the older part of the Carboniferous age, is represented of the 
 natural size in Fig. 116, and is not a restoration, being 
 found preserved entire, though flattened, in a fine bituminous 
 shale, which has perfectly preserved even the most delicate 
 sculpturing of its bony scales 
 
 The Sharks in the Carboniferous increase in number and 
 importance. Fig. 117 shows a few examples of their teeth 
 and spines. In the Carboniferous, however, there is a great 
 
130 
 
 THE CHAIN OF LIFE. 
 
 preponderance of those species with flat, crushing teeth fitted 
 for grinding shells, 1 which in diminishing numbers continue up 
 to the present time, when they are represented by the Port 
 Jackson Shark and a few other species. The increase toward 
 the modem time of the true Sharks 2 with sharp cutting teeth, is 
 obviously related to the increase of the ordinary fishes which 
 
 FIG. 117. Teeth and Spines of Carboniferous Sharks. Nova Scotia. 
 
 Dij>lod-us penetrans. b, Psammodus. c, Cienoptychius cristatus. d, Spine, 
 Gyracanth-us magntficus. One-eighth natural size. Acadian Geology. 
 
 furnish them with food. Another curious difference, connected 
 probably with the same circumstance, is the fact that in the 
 sharp toothed Sharks of the Carboniferous the two side fangs 
 of each tooth are the largest, or are exclusively developed 
 (Fig. 117, a), while in later periods the central point becomes 
 1 Cestracionts. 2 Selachians. 
 
APPEARANCE OF VERTEBRATE ANIMALS. 131 
 
 dominant, or is developed to the exclusion of the others (Figs. 
 118, 119). 
 
 The Ganoids and Dipnoi still, however, occupy a very im- 
 portant place through the Mesozoic ages (Fig. 120), and it 
 is only at the close of the Cretaceous that they finally give 
 place to the Teleosts, or common fishes, which, though perhaps 
 more fully specialised in purely ichthyic features, have dropped 
 the reptilian characteristics of 
 their predecessors (Fig. 121). 
 It is interesting to observe that 
 these old-fashioned fishes had 
 culminated before the advent of 
 air-breathing Vertebrates, which 
 appear for the first time in the 
 Carboniferous. It is further to 
 be observed that groups of fishes 
 furnished with means of aiding 
 their gills by rudimentary lungs 
 were especially suited to waters 
 more charged with carbonic acid, 
 and less with free oxygen, than 
 those of more recent times. 
 This remark especially applies 
 to the mephitic and sluggish 
 streams and lagoons of the 
 Carboniferous swamps, where, 
 
 in the midst of a rank VPp-f FlG - "8. Teeth of Cretaceous Sharks 
 
 (ptocba and Ptyckodus).-A.for Leidy. 
 
 tation and reeking masses of 
 
 decaying organic matter, the half air-breathing fishes and the 
 amphibious reptilian animals met with each other and found 
 equally congenial abodes. Thus, independently of the fact that 
 some of these fishes were probably vegetable feeders, it is not 
 altogether an accident, but a wise adaptation, that caused the 
 culmination of the reptilian fishes and batrachian reptiles to 
 coincide with the enormous development of the lower forms 
 
 K 2 
 
1 3 2 
 
 THE CHAIN OF LIFE. 
 
 of land-plants in the Devonian and Carboniferous. Another 
 curious illustration of the diminishing necessity for air-breathing 
 to the fishes, is the change of the tail from the unequally-lobed 
 
 or heterocercal form, which pre- 
 vailed in the Palaeozoic, to the 
 more modern equally-lobed 
 (homocercal) style in the Meso- 
 zoic. The former is better 
 suited to animals which have 
 to rise rapidly to the surface 
 for air, and is still continued 
 in some modern fishes, which 
 for other reasons need to ascend 
 and descend, or to turn them- 
 selves in the water; but the 
 homocercal form is best suited 
 to the ordinary fish, whether 
 Ganoids or Teleosts (Fig. 122). 
 It is curious also to find the 
 beginning of the dominancy of the ordinary fish to coincide with 
 
 FIG. 119. Tooth of a Tertiary Shark 
 (Carcharodon). 
 
 FIG. 120. A Liassic Ganoid (Dapediiis). Restored. After Nicholson. 
 
 that of the broad-leaved exogenous trees in the later Cretaceous, 
 and to precede immediately the appearance of the mammals on 
 the land ; all these changes being related to the purer air, the 
 
APPEARANCE OF VERTEBRATE ANIMALS. 133 
 
 clearer waters, and the more varied continental profiles of the 
 later geological periods. Thus physical improvement and the 
 changes of animal and vegetable life are linked together by 
 correlations which imply not only design, but prescience, 
 whether we attribute these qualities to a spiritual Creator or 
 to mere atoms and forces. 
 
 ct 
 
 
 FIG. 121. Cretaceous Fishes of the modern or Teleostian type. 
 
 a, Beryx ' Le^vesiensis. English chalk, b, Portheus molossus (Cope). A large fish 
 from the American Cretaceous. One twenty-eighth natural size. 
 
 The history of fishes extends further through geological time 
 than that of any other Vertebrates, and is perhaps more com- 
 pletely known to us, in consequence of the greater facilities for 
 the preservation of their remains in aqueous deposits. If 
 we receive Pander's Conodonts as indicating a low type of 
 
134 
 
 THE CHAIN OF LIFE. 
 
 cartilaginous fishes, these must have continued for vast ages 
 without any elevation, and struggling for a bare existence 
 amidst formidable Cuttle-fishes and Crustaceans, before, under 
 more favourable conditions, they suddenly expanded into the 
 high and perfect types of Ganoids and Sharks. If we reject 
 the early Conodonts, then the two last-mentioned types spring 
 together and suddenly into existence, like the armed men from 
 the dragon's teeth of Cadmus. They rapidly attain to numbers 
 and grandeur unexampled in later times, and become the lords 
 of the waters at the time when there was probably no Vertebrate 
 
 FIG. 122. Modern Ganoids (Folypterus. Africa. Lepidosteus. America). 
 
 life on the land. As the reptiles establish themselves on the 
 land and in the waters, the Ganoids diminish, but the Sharks 
 hold their own. At length the reign of reptiles is over, but the 
 Ganoids, instead of resuming their pristine numbers, give place 
 to the Teleosts, and become reduced to insignificance ; while 
 the Sharks, profiting by the decadence of the great marine 
 reptiles, remain the tyrants of the seas. This history is 
 strangely unlike a continuous evolution ; but we are anticipat- 
 ing facts which will fall to be discussed in a subsequent 
 chapter. 
 
CHAPTER VI. 
 
 THE FIRST AIR-BREATHERS. 
 
 WERE our experience limited to the animals whose 
 remains are found in the earlier Palaeozoic rocks, we 
 might be unable to conceive the possibility of an animal capable 
 of living and breathing in the thin and apparently uncongenial 
 medium of air. More especially would this appear doubtful if 
 our experience of the atmosphere presented it to us as loaded 
 with carbonic acid, and less rich in vital air than it is at present. 
 Even the mechanical difficulties of the case might strike us as 
 considerable, in our ignorance of the capabilities of limbs. 
 Still, as time wore on, we should find this problem worked out 
 along three distinct lines of advancement those of the Mol- 
 lusk, the Arthropod, and the Vertebrate, and in each of these 
 with different machinery, related to the previous locomotive 
 and water-breathing apparatus of the type. 
 
 Respiration under water depends, not on the water itself, 
 but on the small percentage of free oxygen which it contains, 
 and this is utilised for the aeration of the blood of animals, by 
 that wonderful and often extremely beautiful apparatus of deli- 
 cate fibres or laminae penetrated with blood-vessels, which we 
 call a gill. Except those lowest creatures which aerate their 
 blood merely at the general surface of the body, all animals 
 capable of respiration in water are provided with gills in some 
 
138 THE CHAIN OF LIFE. 
 
 form, though in many of the humbler types, like that of the 
 familiar Oyster, the gills are used for the double purpose of 
 aerating the blood and, by their minute vibrating threads or 
 cilia, drifting food to the mouth. 
 
 In the great group of radiated animals, the Protozoa, Calen- 
 terata, and JEchinodermata, no air-breathing creature exists, 
 or, in so far as is known, has existed, so that this vast group 
 of animals is limited altogether to the waters ; and this is 
 undoubtedly one mark of its inferiority. 
 
 In the sub-kingdom of the Mollusks the highest class, that 
 of the Cuttle-fishes and Nautili, has been, singularly enough, 
 rejected as unfit for this promotion, though it was early intro- 
 duced, and attains to a high development of muscular energy 
 and nervous power. The group next in order, that of the 
 Snails and their allies, alone ventures in some of its families 
 to assume the role of air-breathing. As might be expected, in 
 creatures of this stamp the simplest means are employed to effect 
 the result. In the sub-aquatic species the gills are contained in 
 a chamber, where- they are protected and kept supplied with 
 water. In the air-breathing species, this gill-chamber is merely 
 emptied of its contents and converted into an air-sac or func- 
 tional lung. Thus a rude and imperfect method of air-breath- 
 ing is contrived, which scarcely separates the animals that possess 
 it from their aquatic relatives, but which nevertheless gives to 
 us the beautiful and varied groups of the Land-snails and of 
 the air-breathing fresh-water Snails. 
 
 In the worms and Crustaceans the gills are placed at the 
 sides of the body, and connected with its several segments. 
 But the Crustaceans, like the Cuttle-fishes, though the highest 
 aquatic type, never become air-breathers. It is true some of 
 them, like the Land-crabs, live in the air ; but they retain their 
 gills, and have to carry with them a supply of water to keep 
 these moist. 
 
 But in order to elevate the Annulose type to the true dignity 
 of air breathing, three new classes had to be introduced, differing 
 
THE FIRST AIR-BREATHERS. 139 
 
 altogether in their details of structure ; and all three seem to 
 have been placed on the earth about the same time. They are : 
 First, the Myriapods, or Gallyworms and Centipedes ; secondly, 
 the Insects; and thirdly, the Arachnidans, or Spiders and 
 Scorpions. 
 
 In the Myriapods a system of air-tubes, kept open by elastic 
 spiral fibres, penetrates the body by lateral pores, thus retaining 
 the resemblance to the lateral respiration of the Crustaceans 
 and worms. In the Insects, where this type of structure rises 
 to its highest mechanical perfection, and where the animal 
 is enabled to be not merely an air-breather, but a flier, the 
 same system of lateral pores and internal air-tubes is adopted, 
 and is so extended and ramified as to give a very perfect respi- 
 ration. In the Spiders and Scorpions the system is the same, 
 except that in the latter and a part of the former the whole or 
 a part of the tracheal system becomes expanded into air- 
 chambers simulating true lungs. 
 
 Among the Vertebrates, the fishes are breathers by gills 
 attached to arches at the sides of the neck. But already in 
 the Devonian we have reason to believe that there were fishes 
 having the swimming-bladder opening into the back of the 
 mouth to receive air, and divided into chambers, so as to. con- 
 stitute an imperfect lung. And here we have not, as in the 
 lower types, an adaptation of the old water-breathing organs, 
 but an entirely new apparatus. In the next grade of Verte- 
 brates we find, as in the Frogs, Water-lizards, etc., that the 
 young are aquatic and breathe by gills, while the adults ac- 
 quire lungs, sometimes retaining their gills also, but in the higher 
 forms parting with them. Thus in the vertebrates alone we 
 have true lungs, distinct structurally from gills; and these 
 lungs attain to their highest perfection in the birds and 
 mammals. 
 
 The oldest air breathers at present known are Scorpions and 
 insects allied to the modern May-flies, which have been found 
 in the Silurian. Next to these, and more important in number 
 
140 
 
 THE CHAIN OF LIFE. 
 
 and variety, are the insects of the Erian plant beds of New 
 Brunswick. They were discovered by the late lamented Prof. 
 C. F. Hartt in the plant-bearing shales of the Middle Devonian 
 (Fig. 123). The beds containing them hold also a species of 
 Eurypterus, an obscure Trilobite, and a Crustacean allied to 
 the modern Stomapods, 1 besides a shell which may possibly be 
 that of a Land-snail, to be mentioned in the sequel. They 
 are also exceedingly rich in beautifully-preserved remains of 
 
 FIG. 123. Wings of Devonian Insects. Middle Devonian of New Brunswick. 
 
 a, F latephemerct antiqua (Scudder). b, Homothetus fossilis (Scudder). c, Lithen- 
 tomum Harttii (Scudder). d, Xenoneura antiquor-unt (Scudder). 
 
 Devonian plants. The collection made by Prof. Hartt is 
 limited to a few fragments of wings ; but these, in the skilful 
 hands of Mr. Scudder, h,ave proved to be rich in geological 
 interest. One is a gigantic Efhe^tera or May-fly, which must 
 have been five inches in tfre expanse of the wings, which are 
 more complex in their venation than those of its modern allies 
 (Fig. 123, a). Another presents peculiarities between those of 
 the May-flies and Dragon-flies (Fig. 123, b). A third is a 
 Neuropter, not belonging to any known family, but allied to 
 some in the Coal-formation (Fig. 123, c). A fourth (Fig. 1 23, d) 
 
 1 Amphipeltis paradoxm of Salter. 
 
THE FIRST AIR-BREATHERS. 141 
 
 is a small and delicate wing, supposed to have belonged to an 
 animal having some points of resemblance to the modern 
 crickets. Two others are represented by mere fragments of 
 wings, insufficient to determine their affinities with certainty. 
 No other insects of this age have been discovered elsewhere ; 
 but it is to be borne in mind that no other locality rich in 
 Devonian plants has probably been so thoroughly explored. 
 The hard slaty ridges containing these fossils are well exposed 
 on the coast near the city of St. John, and Messrs. Hartt and 
 Matthew of that city, acting, I believe, in concert with and 
 aided by the Natural History Society of the place, not only 
 searched superficially, but removed by blasting large portions 
 of the richest beds, and examined every fragment with the 
 greatest care. Their primary object was fossil plants, of which 
 they obtained magnificent collections ; and it is scarcely possible 
 that the insects could have been found but for the exhaustive 
 methods of exploration employed. 
 
 It is interesting to observe, respecting these oldest insects, 
 that they all belong to those families which have jaws, and not 
 suctorial apparatus, that they are not of those which undergo a 
 complete metamorphosis, and that their modern congeners pass 
 their larval stage in the water. Thus the waters gave birth to 
 the first insects, and their earliest families were not of those 
 which suck honied juices or the blood of animals, or which 
 pass through a worm-like infancy. These groups belong 
 apparently to much later times. 
 
 On one of the specimens collected by Messrs. Hartt and 
 Matthew, and placed by them in my hands, is a spiral form 
 which in every particular of external marking resembles a 
 genus of modern West Indian Land-snails. 1 I have hesitated 
 to describe it, as the structure is lost and the form imperfect ; 
 but I cannot help regarding it as an indication that this group 
 of land animals also will be traced back to the Devonian age. 
 
 1 Genus Slrophia. I have provisionally named the St. John species 
 Str ophites erianus. 
 
142 THE CHAIN OF LIFE. 
 
 Ascending from the Devonian to the Carboniferous, we at 
 once find ourselves in the midst of air-breathers of various 
 types. Here are Myriapods, insects of several orders, Spiders, 
 Scorpions, Land-snails, and Batrachian reptiles, and these of 
 many species, and found in many localities widely separated. 
 We can thus people those dark, luxuriant forests, to which we 
 owe our most valuable beds of coal, with many forms of life; and 
 as most of these belong to tribes likely to multiply abundantly 
 where food was plentiful, we can imagine multitudes of Snails 
 and Millepedes feeding on succulent or decaying vegetable 
 matter, swarms of insects flitting through the air in the sunnier 
 spots, while their larvae luxuriated in decaying masses of leaves 
 or wood, or peopled the pools and streams. In like manner, 
 in imagination we can render these old woods vocal with the 
 trill of crickets and with the piping or booming of smaller and 
 larger Batrachians. Let us now, in accordance with our plan, 
 inquire as to the nature of these early air-breathers and the 
 fortunes of their families in the geological history. 
 
 The Land-snails known as yet in the Carboniferous are 
 limited to five or six species, belonging to four genera, all 
 American and related to existing American forms. The two 
 earliest known are represented in Figs. 124 and I25. 1 One of 
 them is a Pupa, or elongated Land-snail, so similar to modern 
 forms that it does not merit a generic distinction, and is indeed 
 very near to some existing West Indian species. The other is 
 in like manner a member of the modern genus Zonites. These 
 are from the Coal-formation of Nova Scotia, and the Pupa must 
 have been very abundant, as it has been found in considerable 
 numbers in a layer of shale, and in the stumps of erect trees, 
 in beds separated from each other by a thickness of 2,000 feet 
 of strata. The Zonites is much more rare. A second Pupa 
 is found in Nova Scotia, and two species occur in the Coal- 
 field of Illinois. One of these is a Pupa still smaller than 
 
 1 The enlarged figure of Pupa vetusta is too much elongated, and the 
 aperture is somewhat conjectural, as it is usually crushed. 
 
THE FIRST AIR-BREATHERS. 
 
 143 
 
 P. vetusta^ and, like some modern species, with a tooth-like 
 process on the inner lip. The other has been placed in a new 
 
 Km 124. Land-snail (Pupa -vetusia, Dawson). From the Coal -formation. 
 , Natural size, b, Magnified c, Apex, d, Sculpture. Enlarged. 
 
 genus, 1 but is very near to some of the smaller American Snails 
 
 Q 
 
 I 
 
 FIG. 125. Land-snail (Zonites (Conulus) prisons, Carpenter). From the Coal-formation, 
 a, Shell Enlarged ; the line below shows the natural size, b, Sculpture. Enlarged. 
 
 till living. Its most special character is a plate extending from 
 1 Dawsonella of Bradley. 
 
144 THE CHAIN OF LIFE. 
 
 the inner lip over half the aperture, a contrivance for protec- 
 tion still seen in some modern forms. Thus the Land-snails 
 come on the stage in at least three generic forms, similar to 
 those which still live, but all of small size, indicating perhaps 
 that the conditions were less favourable for such creatures than 
 those of the temperate and warmer climates at present. It may 
 seem a small step in advance for Sea-snails to lose their gills 
 and to become Land-snails, and this without any elevation of 
 their general structure ; but it must be borne in mind that we 
 have here not only the dropping of the gills for an air-sac, but 
 profound changes in teeth, mucous glands, shell, and other par- 
 ticulars, to fit them for new food and new habits. It is also 
 singular that the Land-snails at once appear instead of the 
 intermediate forms of the air-breathing fresh- water snails. 
 These last may, however, yet be found. 
 
 The Millepedes, like the Land-snails, were first found in the 
 Coal-formation of Nova Scotia, but species have since been 
 discovered not only in Illinois, but also in Great Britain and 
 in Bohemia. In Nova Scotia alone two genera and five dis- 
 tinct species have been found, all in the interior of erect trees, 
 to which these creatures probably resorted for food and shelter 
 (Fig. 126). All the species yet known are allied to the modern 
 Gallyworms, though presenting special features which seem to 
 separate them as a distinct family, 1 and were probably vegetable- 
 feeders. Some of the species have the peculiarity, unknown 
 among their modern successors, of being armed with long 
 spines. 2 The moist, equable climate and exuberant vegeta- 
 tion of the Coal-period would naturally be very favourable to 
 Millepedes, and it is likely that the discoveries made as yet 
 give but a faint idea of their actual abundance. It is not 
 improbable that they subsequently declined, as we know of 
 none between the Carboniferous and the Jurassic, and they 
 do not seem to have improved up to the modern period. The 
 
 1 Archiulidce of Scudder. 
 
 2 Eupkobeua armige.a (Meek and Worthen), from Illinois. 
 
THE FIRST AIR-BREATHERS. 145 
 
 Carnivorous Myriapods, however, or Centipedes proper, a 
 higher and essentially distinct type, are not known until much 
 more recent times. 
 
 The insects of the Carboniferous as yet known, belong to 
 three out of the ten or more orders into which the class is 
 divided. One of these is represented by a number of species 
 of Cockroach, another by May-flies and a Dragon-fly, and 
 another by some weevil-like Beetles. The Cockroach is cha- 
 racterised by Huxley as one of the " oldest, least modified, 
 
 FIG. 126- Millepedes. From the Coal-formation. 
 
 , Xylobius sigilla.ria (Dawson). b, Arckiulus xylobioides (Scudder) Anterior 
 segments. Enlarged, c, X. farctta (Scudder). Caudal portion. Enlarged. 
 
 and in many ways most instructive forms of insects ; " and both 
 he and Rolleston take its anatomy as typical of that of the 
 class. That these creatures should have abounded in the 
 Coal-period we need not wonder, when we consider the habits 
 of those that infest our houses, and when we further bear 
 in mind the number of species, some of them two inches in 
 length, that exist in tropical climates. So* many species of 
 this family have been found in the Coal-formation on both 
 sides of the Atlantic, 1 that we may fairly regard them as con- 
 stituting one of its most characteristic features, and as probably 
 
 1 About fifty in all, as I learn from Mr. Scudder. 
 
146 
 
 THE CHAIN OF LIFE. 
 
 the oldest representatives of the order to which they belong l 
 (Fig. 127). There were also in the Coal-period insects allied 
 to the Locusts and to the Mantids, a carnivorous group. One 
 of the latter (Lithomantis], described by Woodward, is a mag- 
 nificent insect, not unlike some modern tropical species. It 
 was found in the Coal-formation of Scotland. A still larger 
 species, probably the largest insect known, has been described 
 by Brongniart. The May-flies (Ephemeridcz) are represented in 
 the Carboniferous by several very large species. That of which 
 the wing is shown in Fig. 128 must have been seven inches in 
 
 FIG. 127. Wings of Cockroaches. From the Coal-formation. 
 
 a, Archimulacris Acadicns (Scudder). b, Blattina Bretonensis (Scudder). 
 c, B. Hesri (Scudder). 
 
 expanse of wings. The habits of the modern May-flies show 
 us how animals of this group, living as larvae in the streams 
 and lakes, must have afforded large supplies of food to fishes, 
 and when mature must have emerged from the waters in count- 
 less myriads, filling the air for the brief term of their existence 
 in the perfect state. The May-flies represent another insect 
 order. 2 The Coal-measures of Saarbruck have afforded several 
 species allied to the white ants (Termites], insects which must 
 have found abundant scope for their activity in the dead trees 
 
 Orthoptera. 
 
 2 Neuroptera. 
 
THE FIRST AIR-BREATHERS. 147 
 
 of the carboniferous forests. The occurrence of beetles, 1 espe- 
 cially of the weevil family, which have as yet been found only in 
 Europe, might have been expected, considering the habits and 
 modern distribution of this group. It has been asserted that 
 moths 2 have been found in the Carboniferous ; but the proof of 
 this, so far as known to me, is the occurrence of leaves, noticed 
 by Sternberg, with markings similar to those made by the larvae 
 of minute leaf-mining moths. This, however, is uncertain evi- 
 
 FIG. 128. Wing of May-fly ( H aplopklebinm Barnesii, Scudder). From the 
 Coal-formation. 
 
 dence. If we consider the orders of insects not found in the 
 Coal-formation, we can perceive good reasons for the absence 
 of some of them. Those containing the lice and fleas, and 
 other minute and parasitic insects, we can scarcely expect to 
 find. The bees and wasps, and the butterflies and moths, are 
 little likely to have been present where there were scarcely any 
 flowering plants ; but such groups as those of the two-winged 
 flies, the plant-bugs and the ants, we might have expected, but 
 
 1 Coleoptera. 
 
 Tinea. 
 
 L 2 
 
148 
 
 THE CHAIN OF LIFE. 
 
 for the fact of their being highly specialised forms, and for 
 that reason likely to have appeared later. 1 There are, indeed, 
 as yet no haustellate or suctorial insects known in this early 
 period. Plausible theories of the phylogeny of insects are 
 not wanting ; but they do not well suit the known facts as to 
 their first appearance ; and perhaps we may venture without 
 
 FIG. 129. A Jurassic Sphinx-moth (Sphinx Snelleri, Weyenburgh). 
 
 much blame to apply to the insects of the Coal-period the 
 remark made by Wollaston with reference to the rich insect 
 fauna of the isolated rock of St. Helena : " To a mind which, 
 like my own, can accept the doctrine of creative acts as not 
 necessarily * unphilosophical,' the mysteries [of the existence 
 of these species in an island so remote from other lands], how- 
 
 1 One highly specialised Carboniferous insect recently found is the 
 Frotophasma of Brongniart, a relative of the modern "Walking-sticks." 
 
THE FIRST AIR-BREATHERS. 
 
 149 
 
 ever great, become at least conceivable ; but those which are 
 not able to do this may, perhaps, succeed in elaborating some 
 special theory of their own, which, even if it does not satisfy 
 all the requirements of the problem, may at least prove 
 convincing to themselves." 
 
 The suctorial insects make their first certain appearance in 
 the Jurassic; and the magnificent Sphinx Moth in Fig. 129 is 
 an example of the magnitude and perfection to which that 
 tribe attained in the age of the Solenhofen slate ; though 
 
 FIG. 130. An Eocene Butterfly (Prodryas persephone, Scudder. From Colorado. 
 
 Weyenburgh, who describes it, fancies that he sees evidence 
 that it may, unlike any modern moths, have been provided 
 with a sting. The most perfect and beautiful fossil butterfly 
 known to me is that represented in Fig. 130, from a photo- 
 graph kindly given to me by Mr. Scudder. It is from the 
 Tertiary rocks of Western America, and is laid out in stone 
 as neatly as if prepared by an entomologist, while its preserva- 
 tion is so perfect that even the microscopic scales on the wings 
 can be made out. It belongs to one of the highest types* of 
 
150 THE CHAIN OF LIFE. 
 
 modern butterflies, that to which the Vanessce. belong, but with 
 some points of structure pointing to the lower group of the 
 " Skippers " (Hesperiadcz). Scudder remarks that while the 
 fore-wings resemble those of the former group, the hind-wings 
 look more like those of the latter ; and this seems to be a 
 common character of two or three others of the few fossil 
 species known, none of which are older than the Tertiary. 
 
 We know too little of the spiders and scorpions of the 
 Carboniferous to say more than that they closely resemble 
 modern forms. Two of the scorpions are represented in Figs. 
 131 and 132; and the only spider certainly known, which is 
 
 FIG. 131. Abdominal part of a Carboniferous Scorpion. 1 
 
 from Silesia, is said to belong to the group of the hunting or 
 trap-door spiders (Lycosa)? 
 
 The Batrachians of the Coal are its most characteristic and 
 remarkable air-breathers, especially so as the precursors of the 
 reptiles of the Mesozoic age. Cope in a recent summary 
 enumerates no less than thirty-nine genera and about one 
 hundred species ; and to these have to be added at least a 
 dozen more recently discovered in Europe ; though it was 
 only in 1841 that the first indications of such creatures were 
 found, and were then regarded by geologists with the same 
 scepticism which some of them still apply to Eozoon. The 
 
 1 This was first described as part of the larva of a Dragon-fly. It is now 
 recognised as belonging to a Scorpion. 
 - Protolvcosa (Roemer). 
 
THE FIRST AIR-BREATHERS. 151 
 
 first trace ever observed of batrachians in the Carboniferous 
 consisted of a series of small but well-marked footprints found 
 by the late Sir W. E. Logan in the Lower Carboniferous shales 
 of Horton Bluff, in Nova Scotia. In that year this pains- 
 taking geologist had examined the coal-fields of Pennsylvania 
 and Nova Scotia, with the view of following up his important 
 discovery of the Stigmarm, or roots of Sigillaria, as accom- 
 paniments of the coal-underclays. On his return he read a 
 paper, detailing his observations, before the Geological Society 
 of London. In this he mentioned the footprints in question ; 
 
 FIG. 132. Carboniferous Scorpion (Eoscorpius carbonari-us, Meek and Worthen). 
 Illinois. 
 
 but the paper was published only in abstract, and the import- 
 ance of the discovery was overlooked for a time, the anatomists 
 evidently being shy to acknowledge the validity of the evidence 
 for a fact so unexpected. Fig. 133 is a representation of another 
 slab subsequently found in beds of the same age in Nova 
 Scotia, and which may serve to indicate the nature of Sir 
 William's discovery. In consequence of the neglect of this 
 first hint by the London geologists, the discovery of bones of 
 a batrachian by von Dechen at Saarbruck in 1844, and that of 
 footprints by King in Pennsylvania in the same year, are usually 
 represented as the first facts of this kind. My own earliest 
 discovery of reptilian bones in Nova Scotia was made in 1844, 
 
152 
 
 THE CHAIN OF LIFE. 
 
 though not published till some time afterward, and was fol- 
 lowed up by further collections in company with Sir Charles 
 Lyell in 1851, at which time also the earliest land-snail was 
 found, and in the following year the first millepede. Since 
 that time the progress of discovery has been astonishingly 
 rapid, and has extended over most of the principal coal-areas 
 on both sides of the Atlantic. 
 
 FIG. 133. Footprints of one of the oldest known Batrachians, probably a species of 
 Dendrerpeton. From the Lower Carboniferous of Parrsboro', Nova Scotia. Upper 
 figure natural size. 
 
 We may, for convenience, call these animals reptiles, but 
 they are regarded as belonging to that lower grade of reptilian 
 animals, the Amphibians or Batrachians, which includes the 
 modern frogs and newts and water- lizards. 1 Still it would be 
 doing great injustice to the carboniferous reptiles not to say, 
 
 1 Menopoma, Rlenobranchus, &c.~ 
 
THE FIRST AIR-BREATHERS. 153 
 
 that while related to this low type, they presented a much 
 greater range of organisation than it shows at present, evincing 
 a capability to fill most of the places now occupied by the 
 true reptiles. Some of them were aquatic, and with limbs 
 rudimentary or little developed, but many of them walked on 
 the land, and were powerful and predaceous creatures. They 
 had large and complex teeth, they were protected by external 
 bony plates, and some of them had in addition a beautiful 
 covering of horny plates and spines, and ornamental lappets. 
 Many had well-developed ribs, indicating a condition of respi- 
 ration much in advance of that in the ribless batrachians. 
 Some of them attained to size and strength rivalling those of 
 the modern alligators, while some of the smallest species 
 exhibit characters approaching in some respects to the lizards. 
 
 Perhaps the most fish-like of these animals are those first dis- 
 covered by von Dechen (Archegosaurus, Fig. 134). Their long 
 heads, short neeks, supports for gills, feeble limbs and long 
 flat tail, show that they were aquatic creatures presenting many 
 points of resemblance to the Ganoid fishes which must have 
 been their companions. Yet they show what no fish can 
 exhibit, fore and hind limbs with proper toes y and the complete 
 series of bones that appear in our own arms and legs, while 
 they must have had true lungs and breathed through nostrils. 
 So different are they from the fish in details, that a single limb 
 bone, a vertebra, a rib, or a fragment of a skull bone, suffices 
 to distinguish them. Much has been said recently of the 
 genesis of limbs ; and here, as far as now known, we have the 
 first true limbs ; but it is scarcely too much to say that the 
 feet of Archegosaurus differ more from the fins of any car- 
 boniferous fish than they do from the human hand; while it is 
 certain that the feet which made the impressions represented 
 in Fig. 133, on the lowest beds of the Carboniferous, or that 
 from the upper coal-formation represented in Fig. 139, were 
 not less typical or perfectly formed feet than those of modern 
 lizards. 
 
154 
 
 THE CHAIN OF LIFE. 
 
 Leaving these fish-like forms, we find the remainder of the 
 carboniferous reptiles to diverge from them along three lines. 
 
 The first leads to snake-like creatures, destitute of limbs, 
 and which must have been functionally the representatives of 
 
 FIG. -i^.Archegosaurus Decheni. Head and anterior limb reduced. Coal-field of 
 
 Saarbruck. 
 
 the serpents in the Palaeozoic, though batrachian in their 
 affinities (Fig. 135). They are found both in Europe and 
 America ; and Huxley describes one from Ireland more than 
 
 FIG. 135. Ptyonius. A Snake-like Amphibian. Coal-measures of Ohio. After Cope. 
 
 twenty-one inches long, and with over one hundred vertebrae. 1 
 
 Some extraordinary traces are found on the sandstones of the 
 
 coal- formation, 2 which appear to indicate that there may have 
 
 1 Ophiderpeton Broivnriggii. 2 Diplichnites. 
 
THE FIRST AIR-BREATHERS. 
 
 155 
 
 been species of this type much larger than any represented by 
 skeletons, and with bodies perhaps six inches in diameter. It 
 is not unlikely that they had the habits of the modern water- 
 snakes. 
 
 A second line leads upward to large crocodile-like creatures, 
 with formidable teeth, strong bony armour, and well-developed 
 limbs (Labyrinthodontia^ Figs. 136, 137). Some of them must 
 have attained a length of ten feet. They were lizard-like in 
 form, could walk well, as is seen from the footprints of some 
 of the species which present a considerable stride, and moved 
 
 . 136. A large Carboniferous Labyrinthodont ( Baphetes planiceps, Owen). 
 
 a, Anterior part of the skull, viewed from beneath. One^sixth natural size, b, One of 
 the largest teeth, natural size. 
 
 over mud without the belly touching the ground. Their tails 
 were long, and probably useful in swimming. Their heads 
 were flat and massive, and their teeth were strengthened by a 
 remarkable folding inward of the outer plate of enamel 
 (Fig. 137 ). The belly was protected by bony plates and 
 closely imbricated scales. In some of the species at least the 
 upper parts were clothed with horny scales, and the throat and 
 sides were ornamented with pendent scaly fringes or lappets. 1 
 Their general aspect and mode of life must have resembled 
 
 1 These are known in some of the smaller species, but not as yet in the 
 
 larger. 
 
1 5 6 
 
 THE CHAIN OF LIFE. 
 
 those of modern alligators ; and in the vast swamps of the 
 Coal-period, full of ponds and sluggish streams swarming with 
 fish, they must have found a most suitable abode. While rigid 
 anatomy may ally these animals rather with the batrachians 
 than the true reptiles, it is evident that their great size, their 
 capacity for walking with the body borne well above the ground, 
 their bony and scaly armour, their powerful teeth and their 
 capacious chests, with well-developed ribs, indicate conditions 
 
 FKJ. 137. Baphetes planiceps (Owen). 
 
 a, Fragment of maxillary bone showing sculpture, four outer teeth, and one inner tooth. 
 Natural size, b, Section of inner tooth. Magnified, c, Dermal scale. Natural size. 
 
 of respiration and general vitality quite comparable with those 
 of the highest modem members of the class Reptilia. 
 
 The third line of progress leads to some slender and beau- 
 tiful creatures (Microsauria), chiefly known to us by remains 
 found in erect trees, and which resembled in form and habits 
 the smaller modern lizards. They have simple teeth, a well- 
 developed brain-case, limbs of some length, and bony and 
 
THE FIRST AIR-BREATHERS. 
 
 157 
 
 scaly armour, the latter in some cases highly ornate. 1 They 
 were probably the most thoroughly terrestrial, and the most 
 active of the coal batrachians, if indeed they were not strictly 
 intermediate between them and the lizards proper. Fig. 138 
 
 FIG. 138. A lizard-like Amphibian (Hylonomus aciedentatus). 
 
 a, Maxillary bone ; enlarged. d, Section of tooth ; magnified. 
 
 b, Mandible ; enlarged. e, Scale ; natural size and magnified. 
 
 c, Teeth ; magnified, showing front and side f, Pelvic bone (?) ; natural size. 
 
 view of ordinary tooth and grooved g, Rib ; natural size, 
 anterior tooth. ft, Scapular bone (?) ; natural size. 
 
 i, Palate ; natural size. 
 
 shows some fragments of one of these animals ; and the animal 
 represented in Fig. 139, recently figured by Fritsch, probably 
 belongs to this group. 
 
 1 Hylonomus. See Fig. facing this chapter. 
 
i 5 8 
 
 THE CHAIN OF LIFE. 
 
 FIG. 139. Stelliosaiints longicostatus (Fritsch). Upper Coal-formation of Bohemia. 
 
 The Labyrinthodonts of the Carboniferous continue upward 
 into the Permian, where they meet with the true reptiles ; and 
 in the earlier Mesozoic some of the largest and most typical 
 
THE FIRST AIR-BREATHERS. 159 
 
 examples are found. 1 But here their reign ceases, and they 
 give place to reptiles of more elevated type, whose history we 
 must consider in the next chapter. 
 
 Nothing can be more remarkable than the apparently sudden 
 and simultaneous incoming of the batrachian reptiles in the 
 Coal-formation. As if at a given signal, they came up like 
 the frogs of Egypt everywhere and in all varieties of form. If, 
 as evolutionists suppose, they were developed from fishes, this 
 must have been by some sudden change, occurring at once all 
 over the world, unless indeed some great and unknown gap 
 separates the Devonian from the Carboniferous a supposition 
 which seems quite contrary to fact or unless in some region 
 yet unexplored this change was proceeding, and at a particular 
 time its products spread themselves over the world a supposi- 
 tion equally improbable. In short, the hypothesis of evolution, 
 as applied to these animals, is surrounded with geological 
 improbabilities. 
 
 A remarkable picture of the conditions of Palaeozoic land 
 life is presented by the occurrence of remains of reptiles, 
 millepedes and land-snails in such erect trees as that repre- 
 sented in Fig. 140. In the now celebrated section of the 
 South Joggins in Nova Scotia, trees of this kind occur at 
 more than sixty different levels ; but only in one of these have 
 they as yet been found to be rich in animal remains. Fortu- 
 nately this bed is so well exposed and so abundant in trees, 
 that I have myself, within a few years, removed from it 
 about twenty of them, the greater number affording remains 
 of land animals. 
 
 The history of one of these trees may be shortly stated thus. 
 It was a Sigillaria, perhaps two feet in diameter, and its stem 
 had a dense and imperishable outer bark, a soft cellular inner 
 bark liable to rapid decay, and a slender woody axis not very 
 durable. It grew on the surface of a swamp, now represented 
 by a bed of coal. By inundations and by subsidence, this 
 1 Mastodonsaurus or Labyrinthodon. 
 
i6o 
 
 THE CHAIN OF LIFE. 
 
 swamp was exposed to the invasion of muddy and sandy 
 sediment, and this went on accumulating until the stem of the 
 tree was buried to the height of about nine feet, before which 
 time it was no doubt killed. After a time the top decayed and 
 fell, leaving the buried stump imbedded in the sandy soil, 
 which had now become dry, ,or nearly so. The trunk decayed, 
 its inner bark and axis rotting away and falling in shreds into 
 the bottom of the cylindrical hole, about nine feet deep, once 
 occupied by the stem, and now kept open like a shaft or well 
 by the hard resisting outer bank. The ground around this 
 opening became clothed with ferns and reed -like Calamites, 
 partly masking and concealing it. And now millepedes and land 
 
 FIG. 140. Section showing the position of an erect Sigillaria, containing remains of 
 land animals. 
 
 1. Underclay, with rootlets of Stigmaria, resting on gray shale, with two thin coaly 
 
 seams. 
 
 2. Gray sandstone, with erect trees, Calamites, and other stems: 9 feet. 
 
 3. Coal, with erect tree on its surface : 6 inches. 
 
 4. Underclay with Stigmaria rootlets. 
 
 a, Calamites. c, Stigmaria roots. 
 
 b, Stem of plant undetermined. d, Erect trunk, 9 feet high. 
 
 snails made the buried trunk a home, or fell into it in their 
 wanderings ; and small reptiles sporting around, in pursuit of 
 prey, or themselves pursued, stumbled into the open pitfall, 
 and were unable to extricate themselves, though I have found 
 in some of the layers in these trees trails which show that these 
 
THE FIRST AIR-BREATHERS. 161 
 
 imprisoned reptiles had wearily wandered round and round, in 
 the vain search for means of exit, till they died of exhaustion 
 and famine. The bones of these dead reptiles, shells of land- 
 snails and crusts of millepedes, accumulated in these natural 
 coffins, and became mixed with vegetable debris falling into 
 them, and with thin layers of mud washed in by the rains ; and 
 this process continued so long that a layer of six inches to a 
 foot in thickness, full of bones, was sometimes produced. At 
 length a new change supervened, the area was again inundated 
 and drifted over with sand, and the hollow trunk was filled to 
 the top and buried under many feet of sediment, never to be 
 re-opened till, after the whole had been hardened into sand- 
 stone and elevated to form a part of the modern coast, when 
 
 FIG. 1403:. Section of base of erect Sigillaria, containing remains of land animals. 
 
 Mineral charcoal. b, Dark-coloured sandstone, with plants, bones, &c. c, Gray 
 sandstone, with Calamites and Cordaites. 
 
 the old tree and its forest companions which had shared the 
 same fate with it, are made to yield up their treasures to the 
 geologist. This history is no fancy picture. It represents the 
 results of long and careful study of the beds holding these erect 
 trees, and of the laborious extraction of great numbers of them, 
 and the breaking-up of their contents into thin flakes, to be 
 carefully examined with the lens under a bright light in search 
 of the relics they contained. Fig. n in Chap. I. represents 
 the extraction of one of these trees, which happened to be 
 partially exposed by the wasting of the cliff; but many others 
 had to be laboriously mined out of the rock by blasting with 
 gunpowder. 
 
 It is evident that the combination of circumstances referred to 
 
 If 
 
162 THE CHAIN OF LIFE. 
 
 above could not often occur ; and it is therefore not wonderful 
 that only in one place and one bed has evidence of it been 
 found, and that even in this some of the trees have been filled 
 up at once by sand and clay, or so crushed by falling in or 
 lateral pressure, that they could receive no animal remains. 
 In one respect this is a striking evidence of the imperfection of 
 the geological record, since, but for what may be called a 
 fortunate accident, many of the most interesting inhabitants of 
 the coal forests might have been altogether unknown to us. 
 On the other hand, it shows how strange and unexpected are 
 the ways in which the relics of the old world have been pre- 
 served for our inspection, and that there is probably scarcely 
 any animal or plant that has ever lived of which some fragment 
 does not exist, did we know where to look for it. 
 
 It may be well to remark, in closing this chapter, how many 
 new forms of life, air-breathing and otherwise, make their first 
 appearance in the Carboniferous, and have continued to prevail 
 until now. Here we find the first specimens of Amphibians, 
 Spiders, Myriapods, Orthopterous and Coleopterous Insects, 
 and of the Crabs among ten-footed Crustaceans. In the 
 latter group Woodward has recently described the oldest 
 known crab, from the Coal-formation of Belgium. 
 
M 2 
 
CHAPTER VII. 
 
 THE EMPIRE OF THE GREAT REPTILES. 
 
 HAD we lived in the Carboniferous period, we might have 
 supposed that the line of the great Labyrinthodont 
 liatrachians would have been continued onward and elevated, 
 perhaps, in the direction of the Mammalia, to which some 
 features of their structure point. But we should have been 
 mistaken in this. The Labyrinthodonts, it is true, extend into 
 the Trias ; but there is perhaps a sign of their coming degra- 
 dation in the appearance in the Permian of the first known 
 mud-eel, a humble Batrachian form allied to the Newts and 
 Water-lizards. 1 Their special peculiarities are dropped in the 
 Mesozoic in favour of those of certain small and feeble lizard- 
 like animals, appearing first in the Carboniferous, and more 
 manifestly in the Permian, and which are the true forerunners, 
 though they can scarcely be the ancestors, of the magnificent 
 reptilian species of the Mesozoic, which have caused this 
 period to be called " the age of reptiles." 
 
 The leading reptilian animal from the European Permian 
 has long been the Proterosaurus, from the copper slates of 
 Thuringia (Fig. 141), a reptile of lizard-like form, with well- 
 developed limbs, and attaining a length of three or four feet. 
 It resembles more nearly those large modern lizards known as 
 
 Beinertii of Geinitz. 
 
1 66 
 
 THE CHAIN OF LIFE. 
 
 "Monitors," than any other existing form. The fore-limb 
 represented in the figure foreshadows very closely the bones 
 of the human arm and hand. Besides this we find in the 
 Permian certain lizards (Theriodonts of Owen) which present 
 the remarkable and advanced peculiarity already predicted 
 by some Carboniferous Microsauria, 1 of having distinct canine 
 teeth, producing a division into incisors, canines, 
 and molars, in the manner of the Carnivorous 
 quadrupeds, which they seem also to have 
 resembled in some other parts of their skele- 
 tons. It is not impossible that the foot- 
 prints in the Permian sandstones of Scotland, 
 which have been referred to tortoises, were 
 those of animals of this type. Cope has 
 recently described from the Permian of Texas 
 a number of reptiles which have the complex 
 dentition of the Theriodonts, and others which 
 simulate that of Herbivorous mammals, by the 
 possession of flat grinding teeth supposed to 
 be adapted to vegetable food. 2 The teeth of 
 all these Permian reptiles were set in sockets, 
 also an advanced peculiarity. Thus already 
 in the Permian, before the final decadence 
 of the Carboniferous flora, and while the 
 Palaeozoic invertebrates still lingered in the 
 sea, the age of reptiles dawned, and gave 
 promise of its future greatness by the as- 
 sumption on the part of reptilian species of 
 structures now limited to the Mammalia. 
 But the great Mesozoic reptiles were not fully enthroned, till 
 the Permian, an unsettled and disturbed age, characterised by 
 great earth movements, had passed away, and until that period 
 of continental elevation, with local deserts and desiccation, and 
 much volcanic action, which we call the Trias, had also passed. 
 1 Hyleopeton. 2 Diadictes and Bolasatirus (Cope). 
 
 FIG. 141. Arm of 
 Proterosaurus 
 Speneri. Re- 
 duced. Permian. 
 
. THE EMPIRE OF THE GREAT REPTILES. 167 
 
 Then in the Jurassic and early Cretaceous the reptiles culmi- 
 nated, and presented features of magnitude and structural 
 complexity unrivalled in later times. At the same time the 
 Labyrinthodonts disappear, or are degraded into the humble 
 stations which the modern Batrachians now occupy. 
 
 To understand the reptiles of this age, it will be necessary 
 to notice the subdivisions of their modern representatives. The 
 true reptiles now existing constitute the following orders : 
 i, the Turtles and Tortoises (Chelonia) ; 2, the Snakes (Ophi- 
 dia) ; 3, the Lizards (Lacertilia) 4, the Crocodiles and 
 Alligators (Crocodilia). All of these, except the snakes, are 
 well represented among Mesozoic fossils ; but we have in this 
 middle age of the earth's geological history to add to them 
 from five to seven orders now altogether extinct, and these not 
 
 FIG. 142. Skeleton of Ichthyosaurus. Lias. England. 
 
 of low and inferior organisation, but including species far in 
 advance of any now existing both in elevation and magnitude, 
 and constituting the veritable aristocracy of the reptile race. 
 It will best serve our purpose here to consider chiefly these 
 perished orders and their history, and then to notice very 
 shortly those that now survive. 
 
 The first of the extinct orders is that of the great Sea-lizards, 1 
 of which the now familiar Ichthyosaurus and Plesiosaurus of 
 the English seas, to be seen in all museums and text-books, 
 are the types (Figs. 142, 1420 and 142^). These were marine 
 animals of large size, but not fishes or amphibians. They were 
 true air-breathing reptiles, but with paddles for swimming 
 instead of feet, and some of them with long flattened tails 
 for steering and propulsion. They bore, in short, precisely 
 1 Enaliosauria, including Ichthyopterygia and Sauropterygia. 
 
1 58 
 
 THE CHAIN OF LIFE. 
 
 the same relation to the other members of the class Reptilia 
 which the Whales and Porpoises bear to the ordinary quadru- 
 peds. Some of these animals are believed to have been fifty 
 or sixty feet in length, thus rivalling the Whales, while others 
 
 FIG. 1420. Head of Pliosaurus. Jurassic. Much reduced. 
 
 were of smaller dimensions, like the Porpoises and Dolphins. 
 Some, like the Ichthyosaurus and Pliosaurus (Fig. 1420), were 
 strongly built and powerful swimmers, and able to destroy the 
 largest fishes, while others, like Plesiosaurus, had the body 
 short and compact, the head small, and the neck long and 
 
 FIG. 142^. Paddle of Flesiosaurus Oxoniensis. Jurassic. After Phillips. One-tenth 
 
 natural size. 
 
 flexible, and probably preyed on small animals near the 
 borders of the waters. Catalogues of British fossils alone 
 include about thirty species of Enaliosaurs, which haunted 
 the coasts of Mesozoic Europe, a wonderful fact, when we 
 consider the absence of these creatures from the modern seas, 
 and the probability that only a fraction of the species are yet 
 known to us. 
 
- THE EMPIRE OF THE GREAT REPTILES. 169 
 
 Another remarkable group is that to which Cope has given 
 the name of Pythonomorpha, and which he regards as allied 
 to the serpents, or as gigantic sea-serpents provided with 
 swimming paddles, but which Owen considers more nearly 
 connected with the lizards. In either case they constitute a 
 group by themselves, remarkable not only on account of their 
 anatomical affinities with animals so unlike them in general 
 port, but also for their enormously extended length and formid- 
 able dentition (Fig. 143). Such animals as the Mososaurus 
 of Maestricht and Clidastes of Western America may have 
 exceeded in length the largest Ichthyosaurs and the most 
 bulky of living Cetaceans, though their slender forms and 
 numerous vertebrae remind one of the semi-fabulous sea- 
 serpent, rather than of any known animal of our modern 
 age. They were characteristic of the Later Mesozoic, more 
 especially of the Cretaceous period, and must have been 
 formidable enemies to the fishes of their time. 
 
 Owen has formed two orders 1 for the reception of some 
 remarkable extinct reptiles of this age, found especially in 
 South Africa and India, but also in Europe and America. 
 The first includes large lizard-like animals having horny jaws 
 like those of turtles, and in some of the species with great 
 defensive tusks (Fig. 144). Their mode of life is not well 
 known, but they may have been peaceable and harmless vege- 
 table feeders. The second has been already referred to, in 
 connection with the Permian, where it first appears, though it 
 is continued in the Trias (Fig. 145). The resemblance of 
 the skulls of these creatures to those of Carnivorous mammals 
 is very striking, and nothing can be more singular than their 
 early appearance and their decadence before the advent of 
 those Tertiary mammals which in more modern times occupy 
 their place. 
 
 Perhaps the most extraordinary of all the Mesozoic modifi- 
 cations of the reptilian type was that of the flying reptiles, or 
 1 Anomodontia and Theriodontia. 
 * 
 
170 
 
 THE CHAIN OF LIFE. 
 
 FIG. 144. An Anomodont Reptile of the Trias (Dicynodon 
 lacerticeps, Owen). Reduced. 
 
 FiG. 145. ATheriodont Reptile of the Trias (Lycosanrns). 
 After Owen. Reduced. 
 
 FiG. 146. Skeleton of Fterodochylus crassirostris* 
 Jurassic of Solenhofen. Reduced. 
 
THE EMPIRE OF THE GREAT REPTILES. 171 
 
 Pterodactyls. These were, in short, lizards modified for flight, 
 somewhat in the same manner with the bats among the mam- 
 mals. If the bat may be likened to a flying shrew-mouse, a 
 Pterodactyl may in like manner be compared to a flying lizard ; 
 but the modification in the latter case is by much the more 
 remarkable, inasmuch as the lizard is a cold-blooded animal, 
 and far less likely to be endowed with the active circulation 
 and muscular power necessary to flight than is the mouse. In 
 point of fact, there can be no doubt that the Pterodactyls must 
 have been provided with some approach to a mammalian or 
 ornithic heart, as they certainly were with great breast-muscles 
 
 FIG. 147. Restoration of Rhamphorhyncus Bucklandi. Jurassic of England. After 
 
 Phillips. 
 
 a, One of the teeth. Natural size. 
 
 attached to a keel in the breast-bone for working their large 
 membranous wings. These wings were also somewhat original 
 in their construction. They were not furnished with pinions? 
 like those of the bird, but with a membrane like that of the 
 bat, and this, instead of being stretched over four enormously 
 lengthened fingers, as in that quadruped, was supported on a 
 single elongated finger, corresponding, singularly enough, to 
 the little finger, which usually inconspicuous member consti- 
 tuted in some of these strange creatures a limb longer Jthan the 
 whole body (Figs. 146, 147.) The other fingers of the hand 
 were left free for walking or grasping. They are thus believed 
 to have been able to walk as well as to fly, and even in case of 
 
172 
 
 THE CHAIN OF LIFE. 
 
 need, to swim ; while they could probably perch like birds on 
 rocks and trees. Their heads, though very lightly framed, were 
 large and reptilian in aspect, and furnished with sharp teeth, 
 and sometimes probably with a beak as well. Few creatures 
 of the old world are of more hideous and sinister aspect. Yet 
 some of them must have been as light and graceful on the 
 wing as swallows or sea-gulls. There are many species, most of 
 them small, but some of those in the later Mesozoic attained to 
 so great a size that the expanse of their wings must have ex- 
 ceeded twenty feet, making them veritable flying dragons, 
 
 FIG. 148. A Jurassic Bird ( Archceopteryx macroura). After Owen. 
 
 probably formidable to all the smaller animals of their time. 
 Though these animals were strictly reptiles, they combined in 
 their structures contrivances for aerial locomotion now distri- 
 buted between the bats and the birds. They had bat-like wings 
 and bird-like chests. Some had horny beaks. All had hollow 
 limb bones, and air cavities to give lightness to the skull. Their 
 brains approach to those of birds, and, as already stated, their 
 respiration and circulation must have been of a high order. 
 These facts are very suggestive, and perhaps in no point is the 
 imagination or the faith of the devout evolutionist more severely 
 
. THE EMPIRE OF THE GREAT REPTILES. 173 
 
 tested than in realising the spontaneous assumption of these 
 characters oy reptiles, and their subsequent distribution between 
 the very dissimilar types in which they are now continued. 
 
 The approximation of the winged reptiles to the birds is 
 further increased by the facts that in the Jurassic and Creta- 
 ceous periods there were birds having reptilian tails and 
 probably toothed jaws (Archczopteryx macroura, Fig. 148). 
 The species just named, while in its limbs, trunk, and feathers 
 a veritable perching bird, resembles a reptile in its head and 
 tail. In the Cretaceous of Western America, Marsh has re- 
 cently discovered two distinct types of toothed birds, one 
 having the teeth in regular sockets, the other having them 
 implanted in a groove in the jaw. One of these birds 
 
 FIG. 149. Jaw of a Cretaceous Toothed Bird (Ichthyornis dispar). After Marsh. 
 Natural size. 
 
 (Ichthyo>-nis dispar, Fig. 149) was larger than a pigeon, with 
 powerful wings constructed like those of ordinary birds. It 
 had also the curious and old-fashioned peculiarity of bicon- 
 cave vertebrae, like those of fishes and some reptiles. Another 
 (Hesperornis regalis) stood fiv 7 e or six feet high, and had rudi- 
 mentary wings like those of the Penguins. These toothed 
 birds extend into the Eocene Tertiary, where the Odontopteryx 
 of Owen has been known for some time. In the Eocene, 
 however, this toothed bird is associated with others of ordinary 
 types, allied closely to the Ostriches, the Pelicans, the Ibis, the 
 Woodpeckers, the Hawks, the Owls, the Vultures, and the ordi- 
 nary perching birds. In the Later Mesozoic, indeed, some 
 reptiles became so bird-like that they nearly approached the 
 earliest birds; but this was a final and futile effort of the 
 reptile to obtain in the air that supremacy which it had long 
 
174 
 
 THE CHAIN OF LIFE. 
 
 enjoyed in earth and water ; and its failure was immediately 
 succeeded in the Eocene by the appearance of a cloud of 
 true birds, representing all the existing orders of the class. 
 
 We may close our notice of the winged reptiles of the Meso- 
 zoic by quoting from Phillips his summary of the characters of 
 Rhamphorhyncus (Fig. I47) 1 : "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 the Rhamphorhyncus. If we ask to 
 
 FIG. 150. Jaw of Bathygnathus borealis (Leidy). A Triassic IMnosaur from Prince 
 Edward Island. 
 
 a, Cross section of second tooth, natural size, b, Fifth tooth, natural size. 
 
 which of the many families of birds the analogy of structure 
 and probable way of life would lead us to assimilate Rham- 
 phorhyncus, 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 Cormor- 
 ants and other marine divers which constitute an effective part 
 of the picturesque army of robbers of the sea." 
 1 Geology of Oxford, p. 227. 
 
- THE EMPIRE OF THE GREAT REPTILES. 175 
 
 Lastly, the reptiles, in this age of their imperial sway, cul- 
 minated in the Dinosaurians, animals far above any modern 
 Reptilia in the perfection of their organisation, and many of 
 them of gigantic size. Just as the Pterosaurs filled the place 
 now occupied by the birds, so the Dinosaurs filled that repre- 
 sented by the mammals, or rather they took up a place holding 
 some close relations with both the birds and the mammals. 
 
 FIG. 151. Hadrosaurus Foiilkii (Cope). An Herbivorous Dinosaur, 28 feet long. 
 After Hawkins's restoration. 
 
 There were thus reptilian animals which on the one hand were 
 the elephants and lions of their time, and on the other bore 
 a grotesque resemblance to creatures so unlike these as the 
 Ostriches, in so far as their anatomical structure was concerned 
 while it is evident that their whole organisation places them in 
 the highest position possible within the reptilian class. Some 
 
1 76 THE CHAIN OF LIFE. 
 
 of them must have been herbivorous, and probably slow in 
 movement and quiet in nature. Others were carnivorous and 
 of terrible energy, while furnished with the most destructive 
 weapons (Figs. 152, 153). Many had the power of erecting 
 themselves on their hind-feet and walking as bipeds ; and to 
 adapt them to this end their hinder limbs were very large and 
 strong, and they had long pillar- like tails, while their fore- 
 feet were comparatively small, and used perhaps mainly for 
 prehension (Figs. 151, 154). 
 
 The size of some of these creatures was stupendous. The 
 
 FIG. 152. Jaws of Megalosaurus. After Phillips. One-tenth natural size 
 
 Hadrosaurus of New Jersey, an Herbivorous species (Fig. 151), 
 when erected on its hind limbs and tail, must have stood more 
 than twenty feet in height. Megalosaurus and Iguanodon, of the 
 English Jurassic and Wealden, must have been of still more 
 gigantic size. The former was a carnivorous animal, its head 
 (Fig. 152) four or five feet in length, armed with teeth, sabre- 
 shaped, sharp and crenate on the edges (Fig. 153), its hind 
 limbs of enormous power, so that if our imagination does not 
 fail us in the attempt to realise such a wonder, we may even 
 
THE EMPIRE OF THE GREAT REPTILES. 177 
 
 suppose this huge animal, much larger than the largest ele- 
 phant, springing like a tiger on its prey, a miracle of terrible 
 strength and ferocity, before which no living thing could stand.. 
 Its companion, Iguanodon, was, on the contrary, a harmless 
 herbivorous creature, using its great strength and stature as 
 a means of obtaining leaves and fruits for food, and perhaps 
 falling a prey to the larger Carnivorous Dinosaurs its contem- 
 poraries. A still more bulky animal was the Cefevsaurus, so 
 
 FIG. 153. Tooth of Megalosaurus. Natural size- 
 a, Cross section, b, Crenellation of edges. Enlarged. 
 
 admirably described by Phillips. Its thigh-bone measures 
 more than five feet in length and a foot in diameter ; and it 
 must have stood* ten feet high when on all fours, while its 
 length must have reached forty or fifty feet. It seems from 
 the forms of its bones to have been able to walk on land, but 
 probably spent most of its time in the water, where it may be 
 compared to a huge reptilian hippopotamus. Very recently 
 some bones found in rocks, possibly of Wealden age, in 
 
 N 
 
i;8 THE CHAIN OF LIFE. 
 
 Western America, and described by Cope and by Marsh, 
 indicate that even Ceteosaurus had not attained to the maxi- 
 mum of Diriosaurian dimensions. These new animals have 
 vertebrae twenty inches in length and from twelve inches to 
 thirteen inches in the diameter of their bodies, while their 
 lateral processes stretched three and a half feet. The shoulder- 
 blade of one species is five feet in length, and its thigh-bone 
 is six feet long. From these measurements Cope concludes 
 that, unlike most other Dinosaurs, it had the fore-feet larger 
 in proportion than the hind-feet, so as to have somewhat the 
 appearance of a large giraffe. The bones of the back have a 
 remarkable cavernous structure, which Cope interprets as indi- 
 cating air cavities, to give lightness, as in the case of the bones 
 of birds; but Owen suggests that the cavities were filled 
 with cartilage, and that the animals were aquatic in their 
 habits. Evidently in point of size the Dinosaurs had a better 
 claim than even Behemoth to be called the " chief of the 
 ways of God." Some of them, however, were of small size, 
 and probably active and bird-like in their movements. One of 
 these is the animal represented in Fig. 154, a species from the 
 lithographic limestone of Solenhofen. 1 
 
 Nothing in the life of the Mesozoic has so seized on the imagi- 
 nation of evolutionists as the links of connection between birds 
 and reptiles, which has even been introduced by Huxley into 
 the classification of animals, by his grouping these heretofore 
 very distinct classes in one gigantic and comprehensive class 
 of Sauropsida. It is necessary, therefore, to glance at these 
 connections, and if possible to arrive at some conception of 
 their true value. The links which connect the reptiles and the 
 birds are twofold. First, that between the Dinosaurs and the 
 ostrich tribe, 2 and, secondly, that between the Pterodactyls and 
 
 1 Cope has proposed the names Camerosaurus, Amphiccelius, &c., for 
 these problematical animals. Marsh names them Titanosaurus ; Atlanto- 
 saurus, &c., while Owen holds that some of them at least are identical 
 with his genus Chondrosteosaurus. Seeley and Hulke adopt the name 
 Ornithopsis, and support Cope's view of their nature. 2 Ratitce. 
 
THE EMPIRE OF THE GREAT REPTILES. 179 
 
 their allies, and the peculiar Mesozoic birds, such as Archa- 
 opteryx. The first would serve to account for the few excep- 
 tional Struthious birds of the modern world. The second 
 would account for the Passerine and other more ordinary birds ; 
 and thus, according to evolution, the now somewhat homo- 
 geneous class of birds would have a double, or more probably 
 multiple, origin from several lines of reptilian ancestors. This, 
 no doubt, greatly complicates the links of connection, whether 
 these be supposed to indicate derivation or not. 
 
 FIG. 154. Compsognathus. One of the smaller Dinosaurs. After Wagner. 
 
 If we inquire as to the first connection above stated, we 
 may define it briefly in the words of Prof. Phillips, with 
 reference to Megalosaurus, which "was not a ground-crawler, 
 like the alligator, but moving with free steps, chiefly, if not 
 solely, on the hind limbs, and claiming a curious analogy, if 
 not some degree of affinity, with the ostrich." 1 But the 
 
 1 Woodward in a recent paper refers to a still more curious resemblance 
 of the Dinosaurs to the biped lizard of Australia (Chlamydosaurus], which 
 runs on its hind limbs, and even perches on trees. 
 
 N 2 
 
180 THE CHAIN OF LIFE. 
 
 question arises, Was this resemblance merely that of two 
 oviparous bipeds, or anything more? and when we set off, 
 against the resemblance in haunch bones and hind limbs, the 
 entire dissimilarity in head, in fore limbs, in vertebrae, in tail, 
 and probably in external covering, we are disposed to agree 
 with Huxley in his statement, with respect to the Struthious 
 birds, that their " total amount of approximation to the reptilian 
 type is but small ; and the gap between reptiles and birds is 
 but very slightly narrowed by their existence." There is 
 therefore here a great gap, even in the linking together of the 
 types, independently of any question of derivation. 
 
 The second line of connection appears at first sight more 
 promising. Archaeopteryx has a reptilian tail, and claws on 
 the wing ; and, as it had toothed jaws, like some of the birds 
 in the Cretaceous, must have altogether made a much nearer 
 approach to a reptile than any modern bird does. The re- 
 markable "fish-bird" (Ichthyornis) of Marsh is also very 
 reptilian in some of its characters. But when we compare 
 these reptilian birds with the Pterodactyls and their allies, a 
 vast gap at once becomes apparent. Disregarding the ex- 
 ternal clothing, we find the wing in the two groups entirely 
 dissimilar in details of construction, and this dissimilarity 
 extends to the hind limbs as well, so that the Pterodactyls 
 resemble bats rather than birds. 
 
 Without committing ourselves to any doctrine of develop- 
 ment, we might have rejoiced if our geological discoveries had 
 established a continuous chain, or two continuous chains, of 
 being between the reptiles and the birds ; but this end is evi- 
 dently still far from being attained, though some approximation 
 has undoubtedly been made. To quote again the admission 
 of Huxley : " Birds are no more modified reptiles than reptiles 
 are modified birds, the reptilian and ornithic types being both 
 in reality somewhat different superstructures, raised upon one 
 and the same ground-plan " that ground-plan being the 
 idea of the air-breathing oviparous vertebrate, and the reptile 
 
THE EMPIRE OF THE GREAT REPTILES. 181 
 
 representing the less specialized and less ornate building. 
 As yet the origin of that idea, and the mode of carrying it 
 out to completion, remain unknown, except to the Architect 
 and Builder, who may reveal them to earnest seekers for truth 
 in His own good time. 
 
 As to links of connection with the Mammalia, these are still 
 more obscure. In the Mesozoic the mammals are represented 
 as yet only by a few small species allied to the pouched (Mar- 
 supial) and insectivorous quadrupeds of Australia, and these 
 are closely linked with some of the smaller carnivorous Mam- 
 malia of the early Tertiary ; but neither approach very closely 
 to any known reptilian types. Nor have we yet any connecting 
 links between the great marine reptiles and the Cetaceans and 
 Sirenians which in the Tertiary take their place in the sea. 
 
 It is an interesting fact, to come before us in our next 
 chapter, that the great land reptiles of the Mesozoic survived 
 long enough to become contemporary with 'the introduction 
 and first luxuriance of the modern types of vegetation in the 
 later Cretaceous. It would be natural to suppose that access 
 to these great supplies of better food would have stimulated 
 the increase and development of the herbivorous species, and 
 would have indirectly had the same effect on those that were 
 carnivorous ; but the opposite result seems to have followed, 
 and in the next period the reptiles altogether gave place to the 
 mammals, unless, indeed, they were themselves by some 
 mysterious and comparatively rapid process transformed into 
 Mammalia, to suit them to the better conditions of an improved 
 world. 
 
 So far as yet known, the reign of reptiles was world- wide in 
 its time ; and the imagination is taxed to conceive of a state of 
 things in which the seas swarmed with great reptiles on every 
 coast, when the land was trodden by colossal reptilian bipeds 
 and quadrupeds, in comparison with some of which our 
 elephants are pygmies, and when the air was filled with the 
 grotesque and formidable Pterodactyls. Yet this is no fancy 
 
182 THE CHAIN OF LIFE. 
 
 picture. It represents a time which actually existed, when 
 that comparatively low, brutal, and insensate type of existence 
 represented by the modern crocodiles and alligators was 
 supreme in the world. The duration of these creatures was 
 long, and in watching the progress of creation, they would have 
 seemed the permanent inhabitants of the earth. Yet all have 
 perished, and their modern successors, except a few large 
 species existing in the warmer climates, have become subject 
 to the more recently introduced Mammalia. 
 
 How did the ancient reptile aristocracy perish? We are 
 ignorant of the details of the catastrophe, but their final dis- 
 appearance and replacement by the more modern fauna was 
 connected with a great continental subsidence in the Creta- 
 ceous age, and with changes of climate and conditions pre- 
 ceding and subsequent to it. Yet the struggle for continued 
 dominion was hard and protracted ; and toward its close some 
 of the champions of the reign of reptiles were the greatest 
 and most magnificent examples of the type ; as if they had 
 risen in their might to defy approaching ruin. Thus some of 
 the most stupendous forms appear in the later Cretaceous, 
 after the great subsidence had made progress and almost at- 
 tained its consummation. Like the antediluvian giants, they 
 were undismayed even when the land began to sink beneath 
 their feet ; and for them there was no ark of deliverance. 
 
LOWER CRETACEOUS LEAVES. REDUCED IN SIZE. After Lesquereux. 
 
 a, A ralia Saporteana. b, Sassafras araliopsis. c, Quercus primordialis. 
 
 d, Fagi4s polyclada. e, Salix protecefolia, f, Laurtts proteafolia. 
 
CHAPTER VIII. 
 
 THE FIRST FORESTS OF MODERN TYPE. 
 
 FOR a long time it was believed by geologists that a great 
 and mysterious gap separated the Upper Cretaceous 
 from the oldest Tertiary formations ; and in Western Europe, in 
 so far as physical conditions and animal life are concerned, the 
 severance seemed nearly complete. Oceanic deposits, like the 
 Upper Chalk, are succeeded by beds of littoral and estuarine 
 characters. The last and some of the greatest of the Me- 
 sozoic Saurians have their burial-places in the Upper Cre- 
 taceous, and appear no more on earth. The wonderful 
 shell-fishes of the Ammonite group, and the cuttle-fishes of 
 the Belemnite type, share the same fate. With the earliest 
 deposits of the Eocene Tertiary came in multitudes of large 
 Mammalia heretofore unknown, and the Cetaceans appear 
 in the sea instead of the great marine lizards ; while shells, 
 corals, and crustaceans of modem types swarm in the waters. 
 Thus it is true that a great and apparently somewhat abrupt 
 change takes place at the close of the Cretaceous, and ter- 
 minates for ever the reptilian age. Even in regions like 
 Western America, where physically the later Cretaceous 
 shades gradually into the earlier Tertiary, so that there have 
 been doubts as to the limits of these several periods, the 
 same great change in animal life occurs. 
 
 But a link of connection has at length been found in the 
 history of the vegetable kingdom. The modern flora came 
 
186 THE CHAIN OF LIFE. 
 
 in with its full force in the later Cretaceous, before the end 
 of the reptilian age, and continued onward to the present 
 time. Thus the plant takes precedence of the animal, and 
 the preparation was made for the mammalian life of the 
 Eocene by the introduction of the modern flora in the Cre- 
 taceous period. In like manner it is possible that the great 
 graphite deposits of the Laurentian indicate a vegetation 
 which preceded the swarming marine life of the Cambrian ; 
 and it is not improbable that the Palaeozoic land flora existed 
 long before the first land animals. Thus the plant, as in 
 the old Mosaic record, ever appears on the day before the 
 animal, in each stage of the development of the world. 
 
 In Chapter iv. we traced the history of the old and rich 
 vegetation of the Coal period. But this vegetation con- 
 sisted principally of cryptogams and those lowest phaeno- 
 gams, of the pine and cycad groups, which have naked seeds. 
 In the modern flora we may arrange the several groups of 
 plants, somewhat naturally, as follows : 
 
 Series /., CRYPTOGAMS : 
 
 Class i, Thallophytes, sea- weeds, lichens, fungi. 
 ,, 2, Anophytes, mosses, &c. 
 ,, 3, Acrogens, ferns, lycopods, horsetails. 
 
 Series //., PH^ENOGAMS : 
 
 Class 4, GymnosptrmSj pines, cycads, &c. 
 5, Endogens, palms, grasses, &c. 
 ,, 6, Exogens, oaks, maples, &c. 
 
 With reference to the history of these groups the record 
 stands as follows : In the Palaeozoic age classes 3 and 
 4 culminated, and constituted the great mass of the 
 arboreal vegetation. On entering the Mesozoic, No. 3 
 
THE FIRST FORESTS OF MODERN TYPE. 187 
 
 becomes somewhat diminished, but No. 4 continues with 
 unabated prevalence, so that the Mesozoic has sometimes 
 been characterized as emphatically the age of Gymnosperms. 
 With these appear some Endogens, allied to the modern 
 Yuccas and Screw pines and Arums. But in the lower 
 Mesozoic rocks we have no representatives of the broad- 
 leaved Exogens (Angiosperms), which constitute the great 
 mass of ordinary forest vegetation ; and it is only in the 
 Cretaceous that we find them appearing in force, and that 
 the monotonous vegetation of the older style was replaced 
 by the more beautiful and varied forms of our modern woods. 
 
 In Europe, in the lower part of the Upper Cretaceous of 
 Bohemia (Cenomaruan), have been found some leaves which 
 indicate the beginning of this change. These have been 
 referred to Caesalpinias or Brasilettos, pod-bearing trees of 
 India and tropical America, Aralias or Ginsengs, Magnolias, 
 Laurels, an Ivy, and a peculiar and uncertain genus (Credneria). 
 With these are noble palms, both of the types with pinnate 
 and palmate leaves, and trees allied to the Giant Sequoias of 
 California, and to the Araucarian pines of the' southern hemi- 
 sphere. (See Frontispiece to this Chapter.) These ancient 
 Cretaceous forests of Eastern Europe are compared by Saporta 
 with those which now live in the warmer portions of China or 
 in South America truly a marvellous change from the sombre 
 and uniform vegetation by which they seem to have been im- 
 mediately preceded. A still further development of modern 
 vegetation takes place in the next or highest member of the 
 Cretaceous, the Maestricht beds (Senonian\ where we find a 
 crowd of modern types. On this great change Count Saporta 
 remarks with truth that there seem to have been periods of 
 pause and of activity in the introduction of plants. The 
 Jurassic period was one of inactivity ; and a new and 
 vigorous evolution, as he regards it, is introduced in the middle 
 of the Cretaceous. 
 
 This new and grand elevation of the vegetable kingdom in 
 
1 88 THE CHAIN OF LIFE. 
 
 the Cretaceous age was not local merely. In Moravia, in the 
 Hartz, in Belgium and France, even in Greenland, the same 
 great renewing of the face of the earth was in progress. In 
 America it was proceeding on a grand scale, and seems to 
 have set in earlier than in Europe. 1 In the Dakota group of the 
 West, one of the lower members of the Cretaceous, and cover- 
 ing a vast area, a rich angiospermous flora has been discovered 
 by Hayden, and described by Lesquereux and Newberry, 
 and beds of coal have been formed from its remains. In 
 Vancouver's Island in British Columbia, Cretaceous coal 
 measures occur, comparable in value and in the excellence of 
 the fuel they afford with those of the true coal formation. 
 Some of the beds of coal are eight feet in thickness, and the 
 shales associated with them abound in leaves of exogenous 
 trees generally similar to those still living in America. In these 
 beds are also found mineralized trunks, which present under 
 the microscope the familiar structures of our oaks, birches, 
 and other modern trees. Thus all over the northern hemi- 
 sphere the elevation of the land out of the waters of the great 
 Cretaceous subsidence was signalized by a development of 
 noble and exuberant forest vegetation, of the types still extant. 
 The following list of families found in the Cretaceous, after 
 Saporta, will show the botanist how fully our modern Exogens 
 are represented : 
 
 APETAL^E. GAMOPETAL^E. POLYPETAL^E. 
 
 Myricacea. Apocynacecz. Araliacece. 
 
 Cupulifercz. Ericacecz. Hamameliacecz. 
 
 Betulacecz. Ebenacece, Helleborinea. 
 
 Salicacecz. Myrsinecz. Magnoliacece. 
 
 Morecs. Tiliacefz. 
 
 Proteacecz. Celastracecz. 
 
 Lauracece. Anacardiacecz, 
 
 Myrtacecz. 
 
 1 A poplar occurs in Greenland, in beds held to be Lower Cretaceous. 
 
THE FIRST FORESTS OF MODERN TYPE. 189 
 
 Of the plants in this list, some, like the oaks, birches, willows, 
 and heaths, are common and familiar members of the flora of 
 the northern hemisphere to-day, and even of the European 
 flora. Some, like the Magnolias, Myricas, and witch-hazels, are 
 characteristically American, and a few, like the Proteaceae, are 
 now confined to the southern hemisphere. Some of these 
 families have dwindled since the Cretaceous time, so as to be 
 represented by very few species, or at least have not advanced, 
 while others have multiplied and prospered ; and on the whole 
 the flora of the northern hemisphere seems to have been as 
 rich in this early beginning of our modern forests as it is at 
 the present day. Lesquereux's results, with reference to the 
 American flora of the Dakota group, are very similar, and 
 present some surprising features of resemblance to modern 
 American forests, though he remarks that these Cretaceous 
 trees are generally characterized by the even or unserrated 
 edges of their leaves ; and the same remark seems to apply to 
 the oldest Cretaceous leaves of Europe. 
 
 A very singular feature of the Cretaceous flora is the number 
 of species of some genera now represented by few or even a 
 single species; and this is the more remarkable when we 
 consider how few species, comparatively, of the older flora, are 
 known to us. For example, Lesquereux, though aware of the 
 great variability of the modern Sassafras of America, recog- 
 nizes eight species of this genus in the Dakota Cretaceous, 
 one of which seems to be that still living in America, so that 
 it has continued unchanged, while the others have perished 
 (Fig. 155). Thus this genus culminates at once in the Cre- 
 taceous, but continues still in one of its species. Again, the 
 tulip-tree, Liriodendron, one of the most beautiful, unique, 
 and invariable of American trees, is represented by one sole 
 species in the present world. There seem to be no less than 
 four in the Dakota beds, besides others in the Cretaceous of 
 New Jersey, and one species is found in the Tertiary of 
 Greenland as well as in that of Europe (Fig. 156). There are 
 
190 
 
 THE CHAIN OF LIFE. 
 
 probably four or five species of plane-tree (Platanus} now extant, 
 of which but one occurs in America, unless P. Mexicana, the 
 Mexican plane-tree, is a good species as distinct from the 
 ordinary, more northern, form. There are seven species, accord- 
 ing to Lesquereux, in the Cretaceous of Dakota alone. This 
 sort of evolution backward, or from many species to few, would 
 
 FIG. 155. Sassafras cretaceum (Newberry). 
 
 probably be greatly increased, had we fuller knowledge of the 
 Cretaceous flora, as there are several genera already repre- 
 sented by as many species as they can boast in modern times. 
 We have already seen that this abrupt and sudden culmination of 
 genera and families, and their subsequent decadence, is no rare 
 thing in geology, and it connects itself with that idea of periods 
 of creative activity which we have already had occasion to notice. 
 
THE FIRST FORESTS OF MODERN TYPE. 191 
 
 I have dwelt principally on the phsenogamous plants of the 
 Cretaceous, as presenting the most noteworthy and new 
 
 FIG. 156. Liriodendrtm primavum (Newberry). A Cretaceons Tulip-tree. 
 
 features of the time ; but we must not forget that though cryp- 
 togams were deposed from the high position they held in the 
 Palaeozoic, they still existed; and there are more especially 
 
 FIG. 157. Onoclea sensibilis. Eocene. After Newberry. 
 
 many interesting species of ferns and equisetums in the Cre- 
 aceous and Eocene rocks. These are, however, of modern 
 
192 
 
 THE CHAIN OF LIFE. 
 
 types ; and it is remarkable that some of them appear to have 
 continued without even specific change from the later Cre- 
 taceous up to the present time. A striking illustration of this 
 is afforded by two ferns discovered side by side in the oldest 
 Eocene beds 1 of the plains west of Red River, and described 
 in Dr. G. M. Dawson's report on the 49th parallel. One 
 of these is the well-known and very common Onoclea 
 sensibilis (Fig. 157), or sensitive fern of Eastern America. 2 
 
 FIG. 158. Davallia. tenuifolia. Eocene. After Dawson. Natural size and enlarged. 
 
 This species came into existence at latest at the close of the 
 Cretaceous, and has apparently been continued in America up 
 to the present time. In Europe, where it does not now live, 
 it occurs as a fossil in Eocene beds in the Isle of Mull. The 
 other is Davallia tenuifolia (Fig. 158), a delicate little plant 
 belonging to a genus not now represented in America, and to 
 a species at present found only in Asia. Yet this species also 
 
 1 By some regarded as Upper Cretaceous. 
 
 2 First recognized in American Eocene by Newberry. 
 
i THE FIRST FORESTS OF MODERN TYPE. 193 
 
 lived in America in early Eocene times, but has since been 
 banished, though its former companion, the Onodea, still 
 holds its ground. Such cases of specific persistence along 
 with great changes of habitat are very instructive as to the 
 permanence of species. 
 
 Count Saporta, whose just remarks on the marvellously 
 sudden incoming of the Cretaceous flora we have already 
 referred to, also notices the fact that the families and genera 
 represented in this flora are a most miscellaneous and uncon- 
 nected assemblage, showing either the simultaneous appearance 
 of many dissimilar types, or requiring us to believe in the 
 existence of these and of intermediate forms for a very long 
 period before that in which they are first found. This may, 
 however, be placed in connection with the appearance of 
 an exogenous tree (Syringoxylon) in the Devonian, referred 
 to in a previous chapter. It would be a strange and now little 
 suspected case of imperfection of the record, if it should be 
 found that trees of this type were lurking in exceptional 
 corners through all the vast periods between the Devonian 
 and the Cretaceous, to burst forth in unwonted variety and 
 luxuriance in the latter period. 
 
 The new Cretaceous flora appears first in beds which had 
 been recently elevated from the ocean of the great Cretaceous 
 subsidence ; and when it first flourished, in temperate regions at 
 least, the continents were of small dimensions, and broken up 
 into groups of islands. Farther, America would seem to have 
 had precedence of the Eastern Continent, and the Arctic of 
 the Temperate regions. Thus on the elevation of the later 
 Cretaceous land, plants previously established in the far north 
 spread themselves southward, over newly-raised lands, radiating 
 from the polar regions into Europe, Asia, and America. This 
 seems the only way of accounting for the similarity of the 
 plants in these distant countries. The new flora of the Upper 
 Cretaceous in its journey southward met with a climate probably 
 warmer than the present, yet not so warm as to prevent trees 
 
 o 
 
194 
 
 THE CHAIN OF LIFE. 
 
 similar to those now living in the same latitudes from 
 flourishing. 
 
 Let us now trace this flora through the succeeding ages, in 
 which I shall follow pretty closely some general statements 
 made by Count De Saporta in memoirs recently published. 
 
 At the beginning of the Eocene we find a humid and warm 
 climate in Europe, with great forests of oaks, chestnuts, laurels, 
 giant pines, and other genera, some of them still European, 
 others Asiatic or American, and many of them survivors of the 
 
 FIG. 159. Eocene Leaves. From Aix. 
 
 , Quercus antecedens (Saporta). b, Diospyros pyrifolia (Saporta). c, Myrica 
 Mathesonii (Saporta). 
 
 Cretaceous (Figs. 159 to 162) ; and at the same period similar 
 forests overspread those great plains of North America 
 which were rising from out the Cretaceous sea, and there vast 
 swampy beds were formed of vegetable debris^ giving origin 
 to beds of brown coal, some of them eighteen feet in thick- 
 ness. Then came in Europe and Asia that great subsidence 
 under the sea, during which the Nummuline limestones were 
 deposited, and when the old continent was resolved again 
 into an archipelago of islands, perhaps closely connected 
 
THE FIRST FORESTS OF MODERN TYPE. 195 
 
 with more southern lands. This led to a great increase 
 of southern forms of plants, which does not seem to have 
 occurred to the same extent in America, where the flora 
 
 FIG. 160. An Ancient Clover (Trifolinm 
 talceogceum, Saporta). Eocene. Aix. 
 
 FIG. 161. An Eocene Maple (Acer sei 
 tianus, Saporta). Aix. 
 
 FIG. 162. A European Magnoli of the 
 Eocene (M. diante, Saporta). Aix. 
 
 is more continuous, though showing a warmer climate in the 
 older than in the newer Eocene. At this period Palms, Screw- 
 pines, Proteaceous shrubs, Myrtles, Acacias, and other plants 
 
 o 2 
 
J 9 6 
 
 THE CHAIN OF LIFE. 
 
 of the character of those of more southern climates were 
 dominant in Europe (Fig. 163). The well-known beds of 
 Bournemouth, in the south of England, 1 contain a rich flora 
 of the Eocene age, perhaps of its middle period, and reminding 
 us of the forests of sub-tropical India or Australia. 
 
 Gradual elevation of the land favoured for a time the 
 extension of these plants, and the warmth of the climate 
 
 FIG. 163. Flower and Leaf of Botnbax sepultiflorum. Eocene of Aix. After Saporta. 
 
 A European representative of the Silk-cotton-tree of the East Indies and 
 Tropical America. 
 
 allowed them to extend even into Arctic latitudes. But in 
 the middle of the Eocene another subsidence occurred, which 
 exterminated much of the Eocene flora, and was perhaps 
 accompanied with a reduction of temperature, in which the 
 more northern lands became covered with great forests of 
 trees allied to the Pines. In England a remarkable deposit of 
 1 Described by La Harpe and Gaudin, and recently by Gardner. 
 
THE FIRST FORESTS OF MODERN TYPE. 197 
 
 this age is that of Bovey Tracey, in Devonshire, where beds of 
 clay and brown coal have aiforded a rich flora of American 
 and southern types. The Sequoia shown in Fig. 164 abounds 
 at this place, and is a near relation to the celebrated " big 
 trees " of California ; the Cinnamomum in Fig. 165 is a type 
 equally foreign from modern England. It is a curious feature 
 of the Bovey deposit that immediately above these Eocene 
 beds, holding a rich flora of warm temperate character, are gla- 
 cial clays with leaves of Arctic willows and of the dwarf birch, 
 
 FIG. 164. Branch and Fruit of Sequoia Couttsice (Heer). Eocene. England. 
 
 indicating a climate much more severe than that of the British 
 Islands at present. 1 
 
 In the Miocene period the land again rose, and the northern 
 flora spread itself southward equally over Europe, Asia, and 
 America, so that the Miocene flora of all these regions is very 
 similar ; and this Miocene flora continues substantially to this 
 day in Eastern America and Eastern Asia, except that it has 
 
 1 Recent discoveries have since the publication of the first edition removed 
 the Bovey Tracey beds from the Miocene to the Eocene. See Reports of 
 Mr. Starkie Gardner to the British Association. 
 
I 9 8 
 
 THE CHAIN OF LIFE. 
 
 been greatly reduced in number of species by the intervention 
 of the cold glacial period ; but in Europe and Western America 
 it has been largely replaced by other apparently more modern 
 species. 
 
 A striking result of recent discoveries is the fact that in 
 Cretaceous and Eocene times a very warm climate prevailed 
 
 FIG. 165. Cinnamomum Sckeuchzeri (Heer). Eocene. England. 
 
 in the extreme Arctic regions, and trees of temperate latitudes 
 grew there freely. In the recent Arctic expedition, Captain 
 Fielden found in latitude 81 40', within 600 miles of the 
 Pole, a bed of lignite from twenty-five to thirty feet in thick- 
 ness, associated with remains of plants such as now grow only 
 in temperate latitudes. 
 
THE FIRST FORESTS OF MODERN TYPE. 199 
 
 " From the character of the plant-remains, Dr. Heer infers 
 that the lignite of this locality represents an ancient peat-moss, 
 which must have been of wide extent, with reeds, sedges, 
 birches, poplar, and certain conifers growing on its banks ; 
 while the higher and drier ground in the neighbourhood 
 probably supported a growth of pines and firs, with elms and 
 hazel-bushes. The remains of water-lilies suggest the existence 
 of a fresh-water lake in the old peat-moss, which must have 
 remained unfrozen during a great part of the year." 
 
 It is to be observed with reference to the age of these beds, 
 that as the Later Cretaceous and Eocene flora of Europe and 
 America migrated from the north, the plants found in the beds 
 of that age in the temperate latitudes may really be some- 
 what older in the Arctic regions, a fact which produces some 
 uncertainty as to their actual age. 
 
 The warmth required for the growth of luxuriant forests 
 near the Pole might be secured by a different distribution of 
 land and water, and of the oceanic currents, but the require- 
 ments of plants as to light seem more difficult to meet, and it 
 has been doubted whether species similar to those which 
 are accustomed in modern times to regular alternations of day 
 and night could submit to the long Arctic winter darkness. 
 It is known, however, that in conservatories in Northern Russia 
 plants supplied with heat and moisture can endure in winter 
 great deprivation of light, and at Disco, in Greenland, roses 
 and fuchsias flourish as house plants. 1 These facts show that 
 if there were sufficient light and heat in summer, a great 
 number of the plants of temperate latitudes could endure 
 extreme cold and much deprivation of light in winter. 
 
 ]t may be well here to inform the reader that some confusion 
 as to the succession of the Cretaceous and Tertiary floras in 
 America has arisen from the fact that the plants which are 
 evidently Eocene in Greenland and America have been until 
 lately incorrectly regarded as Miocene in Europe. In the 
 1 Lyell, Principles ; Brown, Ftorula Discoana. 
 
200 THE CHAIN OF LIFE. 
 
 Western States, the Dakota group of Lesquereux is overlain 
 by 2000 feet of Cretaceous beds, containing the marine shells 
 characteristic of that age, but no plants. But in Vancouver's 
 Island these same Upper Cretaceous beds contain an abundant 
 flora, which some botanists have called Tertiary for the rea- 
 son already mentioned. Above the 2000 feet of marine beds 
 overlying the Dakota group is the Lower Lignite group of 
 Lesquereux, holding many fossil plants, including Palms and 
 other evidences of a warmer climate than that of the Cretaceous, 
 and which, constitute a Lower Eocene flora corresponding in 
 some respects to that of Europe. This is succeeded by an 
 Upper Lignite group, also Eocene, but representing a more 
 temperate climate, and therefore resembling more nearly the 
 Cretaceous flora. This is nearly identical with the so-called 
 Miocene of Greenland, Alaska, and Mackenzie River, which 
 the facts collected by the Canadian geologists have shown to 
 be really Eocene. 1 But the Canadian reports containing 
 these facts are comparatively little known in Europe, hence 
 incorrect ideas as to the succession of these floras have been 
 handed from one writer to another, 
 
 To those who adopt extreme views as to the refrigeration of 
 the northern hemisphere in so-called glacial times, there is 
 great difficulty in accounting for the continued existence of 
 the early Tertiary flora ; but if we adopt moderate views as 
 to this, and demand merely a great subsidence, with much 
 reduction of mean temperature, we may suppose that the 
 plants previously existing were preserved on insular spots, 
 whence they were ready to recolonize the land on its emergence 
 from the sea. It seems certain, however, that our continents 
 never regained, after the Glacial period, the exuberance of 
 plant life which they presented in the Miocene and earlier 
 Pliocene ; and we shall find that this statement applies to the 
 world of animals as well as to that of plants. This reduction 
 was more extreme in Europe than in Eastern Asia and Eastern 
 1 G. M. Dawson, Report on ^gth Parallel ; Reports on British Columbia. 
 
- THE FIRST FORESTS OF MODERN TYPE. 201 
 
 America, and the fact is thus accounted for in a recent lecture 
 by Prof. Asa Gray : 
 
 " I conceive that three things have conspired to this loss. 
 First, Europe, hardly extending south of latitude 40, is all 
 within the limits generally assigned to severe glacial action. 
 Second, its mountains trend east and west, from the Pyrenees 
 to the Carpathians and the Caucasus beyond, near its southern 
 border ; and they had glaciers of their own, which must have 
 begun their operations, and poured down the northward flanks, 
 while the plains were still covered with forest, on the retreat from 
 the great ice-wave coming from the north. Attacked both on 
 front and rear, much of the forest must have perished then 
 and there. Third, across the line of retreat of those which may 
 have flanked the mountain-ranges, or were stationed south of 
 them, stretched the Mediterranean, an impassable barrier. Some 
 hardy trees may have eked out their existence on the northern 
 shore of the Mediterranean and the Atlantic coast. But we 
 doubt not, Taxodium and Sequoias, Magnolias and Liquidam- 
 bars, and even Hickories and the like, were among the missing. 
 Escape by the east, and rehabilitation from that quarter until a 
 very late period, were apparently prevented by the prolongation 
 of the Mediterranean to the Caspian, and thence to the Siberian 
 ocean. If we accept the supposition of Nordenskiold, that, 
 anterior to the Glacial period, Europe was 'bounded on the 
 south by an ocean extending from the Atlantic over the present 
 deserts of Sahara and Central Asia to the Pacific,' all chance 
 of these American types having escaped from or re-entered 
 Europe from the south and east is excluded. Europe may 
 thus be conceived to have been for a time somewhat in the 
 condition in which Greenland is now, and indeed to have been 
 connected with Greenland in this or in earlier times. 1 Such a 
 junction, cutting off access of the Gulf Stream to the Polar Sea, 
 
 1 Gray's reasoning is based on the extreme view of the Glacial period 
 now prevalent in America, contrary, as it appears to me, to the actual facts ; 
 but with limitations it holds good on more moderate views as well. 
 
202 THE CHAIN OF LIFE. 
 
 would, as some think, other things remaining as they are, 
 almost of itself give glaciation to Europe. Greenland may be 
 referred to, by way of comparison, as a country which, having 
 undergone extreme glaciation, bears the marks of it in the 
 extreme poverty of its flora, and in the absence of the plants 
 to which its southern portion, extending six degrees below the 
 Arctic Circle, might be entitled. It ought to have trees, and 
 might support them. But since destruction by glaciation no 
 way has been opened for their return. Europe fared much better, 
 but suffered in its degree in a similar way. 
 
 " Turning for a moment to the American continent for a con- 
 trast, we find the land unbroken and open down to the tropic, 
 and the mountains running north and south. The trees, when 
 touched on the north by the on-coming refrigeration, had only 
 to move their southern border southward, along an open way, 
 as far as the exigency required ; and there was no impediment 
 to their due return. Then the more southern latitude of the 
 United States gave great advantage over Europe. On the 
 Atlantic border, proper glaciation was felt only in the northern 
 part, down to about latitude 40. In the interior of the country, 
 owing doubtless to greater dryness and summer heat, the limit 
 receded greatly northward in the Mississippi Valley, and gave 
 only local glaciers to the Rocky Mountains ; and no volcanic' 
 outbreaks or violent changes of any kind have here occurred 
 since the types of our present vegetation came to the land, So 
 our lines have been cast in pleasant places, and the goodly 
 heritage of forest-trees is one of the consequences. 
 
 " The still greater richness of North-east Asia in arboreal vege- 
 tation may find explanation in the prevalence of particularly 
 favourable conditions, both ante-glacial and recent. The trees 
 of the Miocene circumpolar forest appear to have found there a 
 secure home ; and the Japanese islands, to which most of these 
 trees belong, must be remarkably adapted to them. The situa- 
 tion of these islands analogous to that of Great Britain, but 
 with the advantage of lower latitude and greater sunshine 
 
THE FIRST FORESTS OF FOREIGN TYPE. 203 
 
 their ample extent north and south, their diversified configura- 
 tion, their proximity to the great Pacific gulf- stream, by which 
 a vast body of warm water sweeps along their accentuated 
 shores, and the comparatively equable diffusion of rain through- 
 out the year, all probably conspire to the preservation and 
 development of an originally ample inheritance." 
 
 The comparative paucity in species of the west coast of 
 America, though the Sequoias and some other forms which 
 have perished elsewhere are retained there, is admitted to be 
 exceptional, and not easily explained, except by the supposi- 
 tion of peculiar local conditions affecting the comparatively 
 narrow strip of land between the Rocky Mountains and coast 
 ranges, and the Pacific. 
 
 To such widely-distributed and varied and complex pheno- 
 mena as those which have been discussed in the present 
 chapter, it is impossible to do justice in the space at our 
 command. Details in relation to them will be found in the 
 publications of Heer, of Saporta, and of Lesquereux, and are 
 well worthy of study by botanists, to whom alone they can be 
 made fully intelligible. In general, with reference to now 
 prevalent theories of derivation, they present two very dissimilar 
 aspects. No difficulty can be greater to the evolutionist than 
 to account for the simultaneous appearance of so many 
 modern generic forms in the Cretaceous ; and the fact of 
 many of the genera presenting more and more species the 
 farther we trace them back is a strange anomaly of evolution. 
 On the other hand, the number of species continuing un- 
 changed from the Eocene to the Modern, the others only 
 slightly modified, and the representative species occurring in 
 the floras of the old and new continents, appear to many to 
 give great support to the doctrine of gradual transformation of 
 species. Farther facts and farther comprehension of the dif- 
 ference between species and races will be necessary to the 
 settlement of these questions. In the meantime it would 
 appear that the Jurassic flora rapidly gave place, at a particular 
 
204 THE CHAIN OF LIFE. 
 
 point of geological time, to that of the modern world, and 
 this not merely in one locality, but over the whole northern 
 hemisphere ; and there are apparently similar facts in the 
 southern hemisphere as well. It farther appears that each genus 
 was at first represented by many species, and that as time went 
 on these were gradually reduced to a few best suited to 
 survive; and that the changes of climate and level which 
 occurred distributed these over different parts of the con- 
 tinents in a way at first sight very anomalous, but which Prof. 
 Gray somewhat quaintly represents as follows : 
 
 "It is as if Nature, when she had enough species of a 
 genus to go round the four floral regions (Europe, East Asia, 
 West America, and East America), dealt them fairly one at 
 least to each quarter of our zone ; but when she had only two 
 of some peculiar kind, gave one to us, and the other to Japan, 
 Mantchuria, or the Himalayas ; and when she had only one, 
 divided it between the two partners on the opposite sides of 
 the table." 
 
 Lastly, it seems very probable that many so-called species 
 are nothing more than varietal forms, which may very well 
 be modified descendants of Miocene or Eocene plants now 
 figuring in our lists under different names. 
 
C/3 
 
 
 
 '-3 
 P 
 
 j 
 
 ! ? 
 
 I .1 
 
 - 
 
CHAPTER IX. 
 
 THE REIGN OF MAMMALS. 
 
 THE incoming of that highest order of animals in which 
 man himself, in so far as his physical nature is concerned, 
 takes his place, presents some features which, though not un- 
 paralleled in the history of other forms of life, are still very 
 striking. The modern Mammalia are somewhat sharply divided 
 into three very unequal groups. First, those which present in 
 their full perfection the property of producing fully developed 
 young, which is one of the distinctive characters of the class. 
 These are the Placental Mammals. Secondly, those in which 
 the young are produced in a very imperfect condition, and are 
 usually nourished for a time in a marsupium or pouch. These 
 are hence called Marsupials. They are for the most part con- 
 fined to Australasia, though a few occur in America ; and are 
 decidedly inferior in rank to the ordinary mammals. Thirdly, 
 those in which there is a bird-like bill, and also certain bird- 
 like or reptilian peculiarities of skeleton and of the alimentary 
 canal. These are the Monotremes, represented by a very few 
 species in Australia and New Guinea. 
 
 In geological history, so far as the facts are at present known, 
 the second group, that of the Marsupials, antedated the others 
 by a vast lapse of time. The Marsupials appear in the Trias, 
 near the beginning of the Mesozoic period. The Placentals 
 
208 THE CHAIN OF LIFE. 
 
 are not found until we reach the beginning of the Tertiary. 
 The Monotremes would seem to be a comparatively modern 
 degraded type. Thus the Marsupials existed throughout the 
 reptilian age, and this in those countries of the northern 
 hemisphere in which they are not now found. The Mesozoic 
 Marsupials were, it is true, of small size, but there were 
 probably numerous species, and though unable to cope with 
 the great reptiles that swarmed by the shores and on the 
 plains, they may have found abundant scope in the upland 
 and interior regions of the continents. 
 
 The Upper Trias of Germany has afforded to Professor 
 Pleininger two teeth of a small mammal, to which the name of 
 Microlestes antiquus has been given, under the impression that 
 it was carnivorous, though it now seems more likely that it 
 was a vegetable feeder. In rocks of nearly the same age in 
 America, Emmons found a jaw-bone of another species (Dro- 
 matherium sylvestre), which has been supposed to be a near ally 
 of the existing Myrmecobius fasriatus of Australia (Figs. 166, 
 167). In the Stonesfield slate, a member of the English 
 Jurassic, several other species have been found (Fig. 168), and 
 a still larger number in the freshwater beds of the Upper 
 Purbeck. Marsh has obtained many others from the Jurassic 
 of America. None appear to have yet been found in the 
 Cretaceous, but they reappear in the Eocene Tertiary, and 
 continue to the modern time. Their absence in the Cretaceous 
 is probably a mere accident, and they present an illustration of 
 a very permanent type little changed since its first introduction. 
 Lyell enumerates in all thirty-three species from the Mesozoic, 
 all of them of small size, and all more or less nearly related to 
 existing Australian Marsupials, though differing much among 
 themselves, and including both carnivorous and herbivorous 
 forms (Fig. 169). Marsh has recently suggested a somewhat 
 new interpretation of these interesting mammalian remains. 1 
 He considers them divisible into two groups / one allied to 
 1 Geological Magazine, July, 1887. 
 
THE REIGN OF MAMMALS. 
 
 209 
 
 the modern Insectivora (Moles, Shrews, Hedgehogs, &c.), 
 but of generalized forms. For these he constitutes a new 
 order (Pantotheria, Marsh). The other group is less numerous 
 and is Marsupial (Allotheria, Marsh). The jaws in Figs. 166 
 and 1 68 belong to the former group, that in Fig. 169 to the 
 
 FIG. 166. Jaw of Dromatherium sylvestre (Emmons). From the Trias of North Carolina. 
 
 latter. We should thus have both placental and Marsupial 
 mammals in the Mesozoic. Marsh remarks that the descent 
 of these different types from a common ancestry would require 
 us to trace mammals back into the Palaeozoic^ that is, on 
 the doctrine of gradual evolution. 
 
 FIG. 167. Myrmecobius fasciatus. A modern Australian marsupial, allied to Mesozo c 
 
 species. 
 
 So soon as the palaeontologist passes from the Upper 
 Cretaceous to the Eocene, he finds himself in the domain of 
 the placental mammals, which appear in numerous and large 
 species, and this, not merely in one region, but in every part 
 of the world in which these deposits are known to exist. 
 
 p 
 
210 
 
 THE CHAIN OF LIFE. 
 
 Indeed, the recent discoveries in America and in the east of 
 Europe have almost thrown into the shade those researches of 
 Cuvier in the Paris basin which first brought this important 
 fact to light. The Eocene mammals, like the Carboniferous 
 
 FIG. 168 Jaw, and enlarged molar of Phascolotherium Bucklandi. Stonesfield 
 slate. England. After Phillips. 
 
 amphibians, the Mesozoic reptiles, and the Cretaceous forests, 
 appear to spring full-grown from the earth, and this at nearly 
 the same time in every part of the northern hemisphere. It 
 has been suggested that they may have come in gradually 
 without our knowledge in the Cretaceous period; but if so, 
 we should have found some of their remains along with those 
 
 FIG. 169. Flagiauiax Becktesii. Jaw, and pre-molar enlarged, showing flat 
 surface, with ridges. Purbeck. 
 
 of the Upper Cretaceous plants. But the prevalence of the 
 great reptiles up to the close of the Cretaceous would seem to 
 render the co-existence of large mammals unlikely. It has 
 further been supposed that geological changes in the southern 
 
THE REIGN OF MAMMALS. 
 
 211 
 
 and northern hemispheres may have alternated with each ether, 
 so that there may be in the former Cretaceous beds in which 
 the remains of ancestors of the Eocene mammals may be 
 found. But we do not as yet know of such deposits. We 
 may be content, therefore, to suppose that at the close of the 
 Cretaceous there was established somewhere a sort of Eden 
 for the first placental mammals, in which they were introduced 
 and could live unharmed by the decaying monsters of the 
 reptilian age, until the time came when they could increase and 
 multiply and replenish the earth. The nearest approach to 
 
 FIG. 170. Restoration of Palteotherinm magnum. Eocene. After Cuvier and Owen. 
 
 such a centre of mammalian life is perhaps to be found in those 
 great American lake basins embedded in the mountains of 
 the West, which have been so well described by Hayden and 
 Newberry, and which have yielded so many animal remains to 
 the researches of Leidy, Marsh, and Cope. 
 
 The typical deposits of the Early Eocene have long been 
 those of the Basin of Paris, where thick and highly fossilifer- 
 ous deposits of this age rest on the more or less denuded sur- 
 face of the Upper Chalk, and have afforded a rich harvest ot 
 
 p 2 
 
212 THE CHAIN OF LIFE. 
 
 remains of about fifty species of placental quadrupeds, whose 
 bones have been found in the gypsum quarries of Montmartre. 
 The great majority belong to the Ungulates, or hoofed animals, 
 and the most abundant genera are those called by Cuvier 
 Palaotherium (Fig. 170) and Anop father ium, of which there 
 are several species, and which have affinities with the modern 
 Tapirs on the one hand, and with the Horse on the other. Of 
 the Unguiculate or clawed orders there are carnivorous forms 
 allied to the Hyaena and the Fox, a Bat and a Squirrel ; and the 
 Marsupials are represented by an Opossum. Lyell describes a 
 bed of clay associated with the gypsum, in which are numerous 
 footprints, probably produced on the margin of a lake. Many 
 of these might be referred to the Palaeothere and its allies ; 
 but there are others belonging to quadrupeds yet unknown, 
 and there are also tracks of tortoises, crocodiles, and lizards, 
 and of a large wading bird. Such a bed, perhaps deposited on 
 the margin of a salt lake, resorted to as a " lick " by herbivorous 
 animals, and by the carnivorous species which preyed on them, 
 is well fitted, by the thronging life which it indicates, to teach 
 how little we can know of the actual number and variety of 
 the old inhabitants of the earth. 
 
 In England, Eocene beds of the age of those of Paris, occupy 
 the valley of the Thames and the Isle of Wight and neighbour- 
 ing parts of Hants. They have afforded mammalian fossils 
 similar to those of Paris, though less abundantly, but they are 
 rich in remains of marine animals and of land plants. 
 
 Instead of describing the well-known animals of the French 
 and English Tertiaries, from these Eocene deposits upwards, 
 I shall shortly sketch the succession in America, as worked 
 out by Marsh and Cope, with the aid of the admirable summary 
 given by Gaudry of the present state of knowledge with refer- 
 ence to the sequence of mammalian life from its appearance 
 in the Early Eocene up to the present time. 1 
 
 Eocene mammals, especially those gigantic whale-like 
 1 Les Enchainements du Monde Animal. 
 
THE REIGN OF MAMMALS. 213 
 
 creatures called Zeuglodon (Fig. 180), have been found in 
 Eastern North America, but the most remarkable discoveries 
 have been made in the Western Territories, where vast numbers 
 of bones are imbedded in certain ancient and wide-spread 
 lacustrine beds. It may be well to premise here that though 
 the division into Eocene, Miocene, and Pliocene is recognised 
 in America as well as in Europe, the limits of these groups 
 may not precisely correspond with those in the Old World. 
 Still we have this certain point of departure, that the Eocene' 
 begins where the peculiar animals of the Cretaceous end, and 
 that the drying up of the later Cretaceous sea and the esta- 
 blishment of the Eocene land were probably nearly con- 
 temporaneous in both continents. It is true, however, in 
 animals as in plants, that in the successive periods of the 
 Tertiary, America presents an older aspect than Europe, just 
 as its modern fauna still contains such old forms as the 
 opossum. 
 
 It would seem that as the mountain-ranges and table-lands 
 of Western America en:erged from the Cretaceous waters, they 
 became clothed with Eocene forests and inhabited by Eocene 
 mammals. But the waters, dammed up by surrounding ridges, 
 formed large lake basins, which were drained only by the 
 slow excavation of " canons " as the land rose still higher. 
 In the successive deposits formed in these lakes both by 
 ordinary deposition of silt and by paroxysmal showers of 
 volcanic ashes were entombed great numbers of the animals 
 which fed on their banks. It appears that these deposits, 
 which in some places are estimated at not less than 8000 
 feet in thickness, hold the remains of three successive faunas, 
 differing materially from each other, and representing the 
 Lower, Middle, and Upper Eocene. On the flanks of the 
 elevated region supporting the beds formed in the Eocene 
 lakes, are other later lake basins of Miocene age, also 
 abounding in animal remains. East of the Rocky Mountains, 
 and also on the Pacific coast, are still later Pliocene deposits 
 
214 
 
 THE CHAIN OF LIFE. 
 
 holding other and more modern Mammalia. The vast area 
 of these formations and the complete sequence which they 
 show are scarcely equalled elsewhere. 
 
 As in the Paris basin, the large Ungulates constitute the most 
 
 Fi ;. 171 Coryphodon Ha.ma.tus. A Lower Eocene Perissodactyl skull, greatly reduced, 
 showing small size of brain, a. After Marsh. 
 
 conspicuous feature. The great group is now usually divided 
 into those that are odd-toed (Perissodactyl) and those that 
 are even-toed (Artiodactyl). Though; these are apparently 
 arbitrary characters, they .correspond with other more funda- 
 
THE REIGN OF MAMMALS. 215 
 
 mental differences. The first includes such modern animals 
 as the Rhinoceros, Tapir, and Horse. The second includes two 
 somewhat distinct assemblages that with mammillated teeth, 
 of which the Hog and Hippopotamus are types (Bunodonts), 
 and that with crescental plates of enamel in the teeth, of which 
 the Ruminants like the Deer, Ox and Camel, are examples 
 (Selenodonts). 
 
 The most characteristic animals of the lowest Eocene belong 
 to the genus Coryphodon (Figs. 171, 172), which so abounded in 
 Eocene America that bones of about 150 individuals were 
 found by the Wheeler Expedition in one year in the Eocene 
 
 FIG. 172. Fore-foot of Coryphodon. Greatly reduced. After Alarsh. 
 
 beds of New Mexico. These animals in their dentition 
 approached the American tapirs, except that they had great 
 canines like the bear, while their feet resembled those of the 
 elephant, and some of them attained the dimensions of the 
 ox. Coryphodon is thus, as might be expected in a primal 
 placental mammal, a creature of somewhat generalised type. 
 Another point in which it resembles some at least of its early 
 Tertiary contemporaries is the small size of the brain, especially 
 in those parts of it supposed to minister to the intelligence 
 and higher instincts (Fig. 171,0). It is certainly remarkable 
 that as Tertiary time went on the successive groups of mammals 
 were gifted with brains of larger and larger size, fitting them 
 
2i6' THE CHAIN OF LIFE. 
 
 for higher functions, and ultimately for associating with man. 
 Animals thus low in development of brain were probably slow 
 and sluggish and stubbornly ferocious, and dependent on brute 
 force for subsistence and defence ; and they would have been 
 altogether unsuitable for domestication had they lived to the 
 present time. 
 
 In the Middle Eocene, the place of Coryphodon was taken 
 
 FIG. 173. Skull of an Upper Eocene Pefissodactyl (Dinoceras mirabilis\ showing three 
 pairs of horn-bases. Greatly reduced. After Marsh. 
 
 by Dinoceras and allied forms. Some of the species nearly 
 equalled the elephant in size, but had shorter and stouter 
 limbs, each supported on five great toes the most perfect 
 possible sort of pedestal foot (Figs. 172, 174). They were 
 heavily armed with immense canines on the upper jaws, and 
 two or even three pairs of horns or hard protuberances on the 
 head (Fig. 173). Creatures so supported and so armed, and 
 
THE REIGN OF MAMMALS. 
 
 217 
 
 living where food was plentiful, might well dispense with any 
 great degree of intelligence, and their development of brain 
 is consequently little better than that of Coryphodon. These 
 
 FIG. 174. Fore-foot of Dinoceras. Greatly reduced. After Marsh 
 
 great and characteristic Eocene families have no known 
 successors ; and in the Miocene age their place is taken by 
 a very different group, that of which Brontotherium is the 
 
 "^ - ^ *^7^^ 
 
 FIG. 175. Skull of Brcntotheri-itm itigens (Marsh). Greatly reduced. A Miocene 
 Perissodactyl. 
 
 ype (Fig. 175). They are creatures of huge size, with a pair 
 of horn-cores on the nose, and feet with four toes in front 
 and three behind, resembling in form those of the rhinoceros. 
 
218 
 
 THE CHAIN OF LIFE. 
 
 While these gigantic Perissodactyles have no successors as 
 yet known to us, another and less conspicuous Eocene type 
 can be traced onward to modern times by a chain of successors 
 which the imagination of evolutionists has converted into a 
 veritable genetic series, to which they appeal as a ''demon- 
 stration " of the process of descent with specific modifications. 
 In the Lower Eocene are found the remains of a diminutive 
 ungulate (Eohippus)^ of the stature of a moderately-sized dog. 
 It has four toes and a rudiment of a fifth in front, and three 
 toes behind ; and has teeth slightly resembling those of the 
 horse, but more simple and shorter in the crown. In this 
 creature it has been supposed that we have a direct ancestor 
 
 r 
 
 FIG. 176. Series of Equine Feet. After Marsh. 
 
 ic. 1>, Miohippus, Miocene, c. Protohippns 
 Upper Pliocene, e, Eguus, Post-Pliocene and Modern. 
 
 , Orohippus, Eocene. l>, Miohippus, Miocene, c. Protohippns, Lower Pliocene. 
 ci, PliohippiiS) 
 
 of the modern horse. A very similar genus (Orohippus), 
 lacking only the fifth rudimentary toe, replaces Eohippus in 
 the Middle Eocene. Mesohippus of the Lower Miocene is as 
 large as a sheep, and has only three toes on the fore-foot and 
 a splint bone, while its teeth assume a more equine character 
 (Fig. 176). In the Upper Miocene Miohippus continues the 
 line, while Protohippus of the Lower Pliocene is still more 
 equine and as large as an ass, and corresponds with the 
 European Hipparion in having the middle toe of each foot 
 alone long enough to reach the ground. In the Upper 
 Pliocene true horses appear with only a single toe, and splint 
 bones instead of the others. In America, though the horse was 
 
THE REIGN OF MAMMALS. 219 
 
 unknown at the time of the discovery of the continent, several 
 species occur in the Tertiary and Post-Pliocene, showing that 
 the genus existed there up to a comparatively late period ; and 
 when re-introduced it has thriven and run wild in the more 
 temperate regions. What cause could have led to its extinction 
 in Post-Glacial times is as yet a mystery. This genealogy of 
 the horse, independently of its evolutionist application, is very 
 interesting. It shows that some Eocene types were suited to 
 continuance, and even adapted for extension, while others were 
 destined to become altogether extinct at an early date. It 
 shows farther that the power of continuance resided not so 
 much in the gigantic and prominent species as in smaller 
 forms. It is to be observed, however, that Gaudry and other 
 orthodox evolutionists in Europe deduce the horse, not from 
 Eohippus, but from Palaotherium, and that it is equally im- 
 possible to verify either phytogeny, since the mere sequence 
 of more or less closely allied species in time does not prove 
 continuous derivation. Nor indeed are we certain that one- 
 toed horses like those now living did not exist on the dry 
 plains in Eocene times, since the inhabitants of these plains 
 are probably unknown to us. An amusing illustration of the 
 probable reason of the disappearance of the missing links 
 has recently been given by a writer not very favourable to 
 the new philosophy. The several consecutive species may be 
 represented by coins. We may suppose, for example, sixpences 
 to have been coined first, then seven penny and eightpenny 
 pieces, and so on up to a shilling, then pieces representing 
 thirteen, fourteen and fifteen pence, and so on up to a half- 
 crown or crown ; but all the intervening denominations between 
 the sixpence and the shilling, and between the shilling and 
 the half-crown, were found practically of little use. Hence 
 few were coined, and they soon became obsolete. Thus the 
 antiquary would find only a few denominations, and those 
 connecting them would be seldom or never found. It is 
 plain that if we could suppose that nations constructed their 
 
220 THE CHAIN OF LIFE, 
 
 coinage after this unthinking and empirical fashion, and that 
 if we were justified in ascribing a similar procedure to the 
 Creator, it might help to account for the facts as we find 
 them, otherwise we should rather suppose that in both cases 
 something like plan and calculation determined the selection 
 of the species produced, whether of coins or animals. But 
 Chance is a blind goddess, and if we instal her as creator, 
 we must expect the work to proceed by a series of abortive 
 experiments. 
 
 The Perissodactyls are not numerous at present. The 
 three groups represented by the Horse, Rhinoceros, and Tapir 
 constitute the whole ; and the two latter forms can be traced 
 back to predecessors in Eocene times, even more closely 
 resembling them than those supposed to be ancestors of the 
 horse resemble that animal. But the few species now living 
 have thus a vast surplusage of possible ancestors. Many 
 species and genera are dropped without any modern repre- 
 sentatives, so that the tendency has been to a gradual elimina- 
 tion of surplus types, until only a few isolated and somewhat 
 specialised forms remain at present. Yet this process of 
 elimination is not necessarily an evolution or survival of the 
 fittest, in the sense of modern derivationists. It rather implies 
 that in certain past states of the earth the conditions of life 
 afforded scope for many forms not now required, or replaced 
 by other types more suited to the advanced and specialised 
 nature of the world. 
 
 On the other hand, the Artiodactyls have gained in numbers 
 and importance, in comparison with their odd- toed comrades ; 
 and this, though an odd number, namely five, was the typical 
 number with which the earliest quadrupedal forms began life 
 far back in the Palaeozoic. The typical Artiodactyls are those 
 that cleave the hoof, and many of which also chew the cud ; 
 and they are of all others, the horse perhaps excepted, those 
 that are most valuable to man. The lower type (Bunodont), 
 to which the hog belongs, is the older; and many hog-like 
 
THE REIGN OF MAMMALS. 221 
 
 animals occur from the earlier Tertiary upwards. In the 
 Upper Eocene, even-toed species appear with an approach at 
 least to the crescent-shaped teeth of the modern deer and 
 oxen. Some of the species are obviously forerunners of the 
 modern antelopes and deer, though as yet destitute of horns or 
 antlers. Others, like Oreodon, are of more hog-like aspect, 
 though believed to have been ruminants (Fig. 177). These 
 are characteristic of the Middle Miocene, at which stage true 
 deer appear in Europe (Dtcroceras), though they are not known 
 in America until the Pliocene period. The earliest deer have 
 small and simple antlers, these ornaments becoming larger 
 and more elaborate in approaching the modern era. The 
 
 FIG. 177. Oreodon major. A generalised Miocene ruminant, with affinities to the 
 Deer, Camel, and Hog. Greatly reduced. After Leidy. 
 
 hollow-horned ruminants appear for the first time in America 
 in the Lower Pliocene ; and no ancestry has so far been 
 attempted to be traced for them. The antelopes of this group, 
 as well as the gigantic Sivatherium of India, 1 allied to the 
 modern prong-horned antelope of North America, were pro- 
 minent in the Old World in the Miocene. 
 
 A very noteworthy and specially American group of mammals 
 is that of the Edentates, the Sloths and Ant-eaters, a group 
 which a priori we should have supposed would have been one 
 of the earliest in time. They appear, however, first in the 
 Miocene, without even any suggested ancestry, and are repre- 
 1 See Frontispiece to this Chapter. 
 
222 
 
 THE CHAIN OF LIFE. 
 
 sented from the first by large species, though they attain their 
 grandest stature in the Megatherium and Mylodon of the Post- 
 Pliocene (Figs. 178, 179), which were sloths of so gigantic size 
 that they must have pulled down trees to feed on their leaves, 
 
 FIG. 178. Lower Jaw of Megatherium, Greatly reduced. Post- Pliocene of South 
 America. After Owen. 
 
 unless, indeed, there were trees equally colossal for them to 
 climb. But before the modern time, like the American horses, 
 the larger herbivorous forms suddenly disappear, and are now 
 
 FIG. 179. Ungual Phalanx and Claw-core of Megatherium. Greatly reduced. 
 
 represented only by a few diminutive South American species, 
 which can scarcely, by any stretch of imagination, be supposed 
 to be descendants of their gigantic predecessors. The history 
 of these animals, like those of the great Tertiary marsupials of 
 
THE REIGN OF MAMMALS. 223 
 
 Australia and the many Miocene elephants of India, affords a 
 remarkable illustration of the persistence of similar groups of 
 creatures in successive ages in the same region, along with 
 diminution in magnitude and number of species toward the 
 modern times. 
 
 The Whale-tribe (Cetaceans) at once in the earliest Eocene 
 takes the place of the great Sea-lizards of the Cretaceous ; and 
 the oldest of the whales are in their dentition more perfect 
 
 FIG. i So. Tooth of Eocene Whale (Ze2tglodon cetioides). One-half natural size. 
 
 than any of their successors, since their teeth are each implanted 
 by two roots, and have serrated crowns, like those of the Seals. 
 The great Eocene whales of the Southern Atlantic (Zeuglodon) 
 (Fig. 1 80), which have these characters, attained the length of 
 seventy feet, and are undoubtedly the first of the whales in 
 rank as well as in time. This is perhaps one of the most 
 difficult facts to be explained on the theory of evolution. 
 Allied to the whales is the small and peculiar group of the 
 
224 THE CHAIN OF LIFE. 
 
 Sea-cows or Dugongs (Sirenians). These creatures, highly 
 specialised and very distinct from all others, appear in the 
 Early Tertiary in forms very similar to those which now exist, 
 and probably in much more numerous species, and they pursue 
 the even tenor of their way down to modern times without 
 perceptible elevation or degradation. " We have questioned," 
 says Gaudry, when speaking of the Tertiary Cetaceans, " these 
 strange and gigantic sovereigns of the Tertiary oceans as to 
 their progenitors they leave us without reply." Their silence 
 is the more significant as one can scarcely suppose these 
 animals to have been nurtured in any limited or secluded space 
 in the early stages of their "development. The true Seals, 
 which are more elevated than the Whales, and very different in 
 type, appear much later, and without any probable ancestry. 
 
 The Elephants, two or three species of which constitute in 
 the modern world the sole representatives of an order, are a 
 remnant of an ancient race once vastly more numerous. They 
 appear in Europe and Asia in the Miocene, when they were 
 represented by three distinct genera (Elephas, Mastodon, and 
 D mother iuni}. The second genus (Fig. 181) differs from the 
 proper Elephants in having tuberculated teeth, indicating a 
 more swinish habit, and probably a more fierce disposition. 
 The third (Fig. 182) is remarkable for the immense size of some 
 of its species, far exceeding the modern Elephants, and has the 
 farther peculiarity of a pair of descending tusks on the lower 
 jaw, constituting a strong and heavy grubbing-hoe, with which 
 it could probably dig deeply for roots. So important was the 
 group in Miocene times that seven elephants are already known 
 from this formation in India alone, besides three species of 
 Mastodon. Four or five Miocene Mastodons are known in 
 Europe, besides two Dinotheria; and the true Elephants appear 
 there in the Pliocene, and continue to the beginning of the 
 Modern. The elephantine animals are not known in America 
 till the Pliocene, but in that and the Pleistocene, and perhaps 
 up to the human period, the western continent, now altogether 
 
THE REIGN OF MAMMALS. 
 
 225 
 
226 
 
 THE CHAIN OF LIFE. 
 
 destitute of elephants, possessed several species both of Elephas 
 and Mastodon, which extended, as in Siberia, even into the 
 Arctic regions ; and, as we know from specimens preserved in 
 a frozen state in the latter region, some of the species were so 
 protected by dense fur as to be able to endure extreme cold. 
 The candid Gaudry closes his summary of the history and 
 affinities of the elephantine animals with the words : " How- 
 ever, the sum of the differences compared with that of the 
 
 FIG. 182. Head of Dinotherium gigctnteum. 
 Greatly reduced. Miocene of Europe. 
 
 FIG. 183. Wing of Vespertilio 
 aquensis. An Eocene Bat. 
 After Gaudry. 
 
 resemblances is too great to permit us to indicate any relation 
 of descent between the proboscidians and the animals of other 
 orders known to us at present." So these greatest of all the 
 animals of the land, with their strangely specialised forms and 
 almost human sagacity, stand alone, without father or mother, 
 without descent. 
 
 The Rodents, or gnawing animals, appear in the Early Eocene 
 on both continents in familiar forms allied to our Squirrels and 
 
THE REIGN OF MAMMALS. . 227 
 
 Rats. Porcupines and Beavers are added in the Miocene. 
 This group seems thus to have continued much as it was ; and 
 it is still perhaps represented by as many species as at any 
 previous time. Many of the ancient forms were, however, much 
 larger than any modern species, and some of these larger forms l 
 present singular points of approach to very distinct types, as, for 
 example, to that of the Bears ; but these large and composite 
 species are long since extinct. The insectivorous mammals 
 have much the same history with the Rodents. Such highly 
 specialised and abnormal forms as the Bats might be supposed 
 to be modern. But, strange to say, they appear with fully 
 developed wings both in Europe and America in the Eocene 
 (Fig. 183). Gaudry thinks that it is " natural to suppose " that 
 there must have been species existing previously with shorter 
 fingers and rudimentary wings ; but there are no facts to support 
 this supposition, which is the more questionable since the sup- 
 posed rudimentary wings would be useless, and perhaps harm- 
 ful to their possessors. Besides, if from the Eocene to the 
 present the Bats have remained the same, how long would it 
 take to develop an animal with ordinary feet, like those of a 
 shrew, into a bat ? 
 
 The Early Eocene was not altogether a time of peace in the 
 animal world. The old carnivorous Saurians were dead and 
 buried, but their place was taken by carnivorous mammals, 
 allied to our modern Tigers, Hyaenas, Foxes, and Weasels. 
 The Carnivora, however, were subordinate in the Eocene, and, 
 as already remarked, some of them appear to be intermediate 
 between -marsupial and placental forms a fact which evolu- 
 tionists have noticed with much satisfaction. They appear to 
 attain to their culmination in the Miocene, when their powers 
 seem to be proportionate to those of the great and well-armed 
 quadrupeds they had to deal with. To this age belongs the 
 introduction of the terrible " Cymetar-toothed Tiger" (Mach- 
 
 1 For example, Tillotherium of the American Eocene, which was as large 
 as a tapir 3 and in form resembled a bear. 
 
 Q 2 
 
228 
 
 THE CHAIN OF LIFE. 
 
 airodus, Fig. 184). Its huge tusk-like canines and powerful 
 limbs seem to fit it more than any other of the cat family 
 for destructive efficiency. Yet ordinary cat-like animals were 
 contemporary with it, and have survived it, since Machairodus 
 disappears in the Post-Pliocene, though in previous periods it 
 had been very widely distributed on both continents. It is a 
 curious fact, perhaps of more significance in various ways than 
 we yet understand, that the Dog-bear (Arctocyon\ of the oldest 
 
 FIG. 184. Skull of a Cymetar-toothed Tiger ( 'Machairodus cultridens). Pliocene, 
 France. Reduced. 
 
 French Eocene, believed to be the oldest placental mammal 
 known, though technically placed among the Carnivora, has a 
 kind of dentition indicating that, like the modern Bears, it was 
 really omnivorous; and its skull shows some peculiarities 
 tending to those of the Marsupials. 
 
 Much interest attaches to the first appearance of the order of 
 Apes (Quadrumana\ or, if we take the somewhat deceptive 
 classification favoured by some modern zoologists, the Primates^ 
 
THE REIGN OF MAMMALS. 
 
 229 
 
 including the apes and man. They begin in the Eocene, both 
 in Europe and America, with the lowest tribe, that of the 
 Lemurs, now confined to the island of Madagascar and parts 
 of Africa and Southern Asia, and which may, Gaudry thinks, 
 be modified Marsupials, though he admits that this is hard to 
 understand. He mentions the resemblance of the teeth of 
 monkeys to those of some hog-like animals, a resemblance, 
 however, merely marking a similarity of food, and suggests on 
 this ground that some of the primitive ancestors of the hog 
 
 FIG. 185. Lower Jaw of Dryopithecus Fontani. An Anthropoid Ape of the Middle 
 Miocene of France. Natural size. 
 
 may have also given rise to the Monkeys. In the Miocene of 
 Europe and Asia we have true Apes ; and one of these, which 
 rivals man in stature (Dryopithccus), belongs to the group of 
 the gibbons, or long-armed apes, one of the higher families of the 
 modern Qiiadrumana (Fig. 185). This animal presents, indeed, 
 the nearest approach to man made by any Tertiary mammal. 
 Still the differences are great, as, for instance, in the much 
 larger size of the canines and premolars. Yet so much con- 
 fidence has Gaudry in the resemblances, that he even ventures 
 
230 THE CHAIN OF LIFE. 
 
 to suggest that certain flint chips found in the Miocene of 
 Thenay, and which have been supposed to indicate human 
 workmanship, may have been chipped by the hands of 
 Dryopithecus. Should this view be adopted by evolutionists, 
 it will at least have the effect of preventing flint chips from 
 being received as evidences of the antiquity of man. 
 
 It is scarcely necessary to sum up this review of the history 
 of the Tertiary mammals. Much that has been said may be 
 modified or changed by future discoveries ; but the great facts 
 of the late appearance of the placental mammals, of their 
 rapid introduction, with their ordinal differentiation nearly 
 complete over all the continents, of the speedy culmination 
 and early decadence of many types, and of the unchanged 
 permanence of others, must in the main be sustained. It is 
 not too much to say that to account for these facts the evolu- 
 tionist must abandon the idea of gradual change, and adopt 
 that of "critical periods" when sudden changes occurred. The 
 history becomes inexplicable, unless with Mivart, Le Conte, and 
 Saporta, we admit "periods of rapid evolution" alternating 
 with others of stagnation or retrogression ; and if we admit 
 these, we practically fall back on the old idea of creation ; only 
 it may perhaps be " Creation by Law." 
 
CHAPTER X. 
 
 THE ADVENT OF MAN. 
 
 HITHERTO we have met with no trace of man or of his 
 works. Yet (here have been in our upward progress 
 from the dawn of life mute prophecies of his advent. Man is 
 in his bodily frame a vertebrate animal and a mammal; and 
 when first the Amphibians were introduced in the Palaeozoic, 
 the framework of man's body was already sketched out and 
 its principles settled. Those great reptilian lords, the biped 
 Saurians of the Mesozoic, already foreshadowed his erect 
 posture, though their limbs may have been more ornithic than 
 mammalian. The gradual advance in the brain-development 
 of the Tertiary mammals presaged a coming time when mind 
 would obtain the mastery over claw and tooth and horn ; and 
 in the Miocene ages there was already some hint of the precise 
 style of structure in which this new creative idea would be 
 realised. Yet it might have been impossible to imagine 
 beforehand the vast changes which this new idea would inau- 
 gurate. In the lower animals such intelligence as they possess 
 is so tied to the physical organisation that it manifests itself as 
 a mechanical unvarying instinct. Man bursts this bond, and in 
 doing so revolutionises the whole scheme of nature. Old things 
 are now put to new uses, the face of nature is changed, varied 
 arts are introduced, and thought enters into the domain of 
 
234 THE CHAIN OF LIFE. 
 
 general and abstract truth. Objects are arranged, classified, 
 understood, and while in some respects the whole creation is 
 made to groan under the tyrannous inventions of man, yet 
 these are the inventions of imagination and design. They 
 are the triumph, not of brute force, but of will and 
 intelligence. 
 
 That man was not in all the earlier ages of the world, except 
 in these prophecies of his coming, geology assures us. That he 
 is, we know. How he came to be, is, independently of Divine 
 revelation, an impenetrable mystery one which it is doubtful if 
 in all its bearings science will ever be competent to solve. Yet 
 there are legitimate scientific questions of great interest relat- 
 ing to the time and manner of his appearance, and to the con- 
 dition of his earlier existence and subsequent history, which 
 belong to geology, and in which so gr<!at stores of material 
 have been accumulated that a treatise rather than a chapter 
 would be required for their discussion. We may endeavour 
 to select a few of the more important points. 
 
 One of the first questions meeting us is that which relates 
 to the point in geological time signalised by the advent of our 
 species. In the Eocene period our continents were being gra- 
 dually raised out of the ocean, and were still in great part under 
 the waters, which several times returned upon the land, and 
 seemed ready again to engulf it. In this period not only have 
 we no traces of man, but all the higher animals of that age are 
 now extinct. In the later Eocene and Miocene the extent of 
 land became greater, but it was so disposed as to allow the 
 influx into the Arctic Sea of vast volumes of heated water from 
 the equatorial regions ; "and there may have been also astro- 
 nomical causes at work to increase this influx of warm water, 
 and so to raise the temperature of the Arctic regions still 
 higher. 1 The middle period of the Tertiary was undoubtedly 
 a time very favourable to the wide distribution of the higher 
 forms of life both animal and vegetable. But we cannot trace 
 1 Croll, Climate and Time. 
 
THE ADVENT OF MAN. 235 
 
 man or any of the contemporary mammals back to the Mio- 
 cene. In the Pliocene the continents had attained to their 
 present elevations, and climates were not dissimilar from those 
 prevailing at present; but still we have no certain indication 
 of the presence of man ; and if other modern mammals extend 
 back to this period their number is very small. In this age 
 also the greater part of the continents must have been covered 
 with a great thickness of soil and disintegrated rock favourable 
 to vegetation, and there seemed nothing to preclude the intro- " 
 duction of man. But a new and at first sight most unfavourable 
 change was to intervene. Whether through internal changes 
 affecting the distribution of land and water, or through astro- 
 nomical vicissitudes, the northern hemisphere, and possibly the 
 whole world, entered on an era of refrigeration, the so-called 
 " Glacial Age " of the Post-Pliocene or Pleistocene period. 
 That in this period our continents as far south as the latitude 
 of 40 were overwhelmed with ice or ice-laden seas is rendered 
 evident by the fact that the whole surface up to several thou- 
 sands of feet above the sea-level has been bared of its accu- 
 mulated debris and polished and grooved by ice, and laden with 
 boulders and other glacial deposits, while in many places at 
 heights of even 1,000 or 1,200 feet these deposits contain sea- 
 shells of species now living in the colder parts of the ocean. 
 These phenomena do not exist in the tropical regions, except in 
 the vicinity of high mountains, but they recur in the southern 
 hemisphere. It is still uncertain whether the period of greatest 
 cold in the two hemispheres was at the same time or in 
 successive ages. Geologically, however, they are approximately 
 contemporaneous, both occurring between the end of the 
 Pliocene and the modern period ; but nevertheless they may 
 not have coincided in absolute date. 
 
 Very different views have been held as to the precise condi- 
 tion of the continents in the Glacial Age, though all agree in 
 the prevalence of cold and the action of ice, and in the fact 
 of a great submergence at one or more stages of the period. 
 
236 THE CHAIN OF LIFE. 
 
 My own conclusions, which I have advocated elsewhere, 1 and 
 which are based on extensive study of the northern parts of 
 America, where the deposits of this age are more widely 
 developed than elsewhere, are that there was one great subsi- 
 dence, leading to a condition in which the lower levels of the 
 continents were covered with ice-laden water and the higher 
 regions were occupied with permanent snow and glaciers. This 
 submergence went on till even high mountains 4,000 feet or 
 more in elevation were under water. Then there was a gradual 
 though intermittent elevation, during which the climate became 
 ameliorated, and lastly there was a condition in which the land 
 of the northern hemisphere stood higher than at present, and 
 which immediately preceded the modern period. As these con- 
 ditions have great significance in relation to the appear- 
 ance of man, I have tabulated them for reference as they occur 
 in Scandinavia, Great Britain, and North America. The so- 
 called " Interglacial Periods " of some geologists are in reality 
 local results of the stages of intermittent elevation in which 
 "were deposited beds which in some cases, as in Scotland, 
 Sweden, and Eastern Canada, hold sea-shells, and in others, 
 as in the central areas of North America, contain remains of 
 plants of northern species. 
 
 We shall name, for convenience, the parts of this Pleistocene 
 revolution which include the great subsidence and glaciation, 
 the Glacial Age, that extending from the re-elevation to the 
 modern the Post-glacial. 
 
 The Glacial Age proved fatal to a large proportion of the 
 land life of the previous periods. According to Professor Boyd 
 Dawkins, out of fifty-three species known in Britain in the 
 Post-glacial, only twelve are survivors of the Pliocene ; and 
 probably the proportions would not be greater in any part of 
 the northern hemisphere. Some, however, did survive, either 
 by migrating southward or by being inhabitants of places 
 less severely affected than most by the general cold and 
 
 1 Notes on Post-Pliocene of Canada ; Acadian Geology, 3rd edition. 
 
THE ADVENT OF MAN. 
 
 237 
 
 submergence. There was thus no absolute break in the chain 
 of life effected by the Glacial Age. 
 
 TABLE OF PLEISTOCENE DEPOSITS IN SCANDINAVIA, ENGLAND, AND 
 AMERICA. (Order descending. ) 
 
 SCANDINAVIA. 
 (Torell.) 
 
 GREAT BRITAIN. 
 (Lyell, &c.) 
 
 NORTH AMERICA. 
 
 Valley-clays and Heath- 
 sands of Sweden. (No 
 fossils.) 
 
 Terrace-gravels of Nor- 
 way and Sweden. (No 
 fossils.) 
 
 Hoxne Deposits and Upper 
 Terrace Gravels. Palaeo- 
 lithic Implements. 
 
 Upper Glacial Beds. 
 Bridlington Beds. 
 Upper Boulder Beds. 
 
 Terrace Gravels and Loess 
 Deposits. 
 
 Placer Gravels of West. 
 
 Do. Sand and Gravel, 
 Newer Boulder Drift. 
 
 Dryas-clay with Fossil 
 plants of northern 
 species. 
 
 So-called " Interglacial" 
 Deposits. 
 
 So - called Interglacial 
 Beds, with Plants, &c. 
 
 Loess Deposits of Missis- 
 sippi. 
 
 Uddevalla beds with Boreal 
 Marine shells. 
 
 Clyde Beds and Marine 
 Clays. 
 
 Upper Leda Clay and 
 Champlain Clay, with 
 Boreal Shells. 
 
 
 
 White Silts of British 
 Columbia. 
 
 
 Mid-Glacial Sands. 
 
 Erie Clays and similar 
 Beds of West. 
 
 Yoldia Clay and Sand. 
 Arctic Marine Shells. 
 
 
 Lower Leda Clay, with 
 Arctic Shells. " 
 
 Yellow Stony Clay and 
 Sand, and Gravel of 
 
 Scania. 
 
 
 Port Hudson Deposit of 
 Mississippi. 
 
 "Syrtensian" Beds of 
 New Brunswick. 
 
 
 
 Orange Sand of Mississippi. 
 
 "Moraines de Fond," or 
 Boulder Clay proper. 
 
 Till, or Older Boulder 
 Clay. 
 
 Boulder Clays, with Local 
 and some Travelled 
 Boulders. 
 
 Ancient Diluvial Sand. 
 
 Pebbly Beds and Wey- 
 burne Sands, Lignitic 
 Forest Beds. 
 
 Old Land Surfaces Peat 
 under Boulder Clay, 
 Local Gravels and 
 Sands. 
 
 
 
 Pre-glacial Gravels of 
 British Columbia. 
 
238 THE CHAIN OF LIFE. 
 
 In what part of this sequence did man appear ? In answer 
 to this, I think it is now generally admitted that he is not 
 certainly known earlier than the Post-glacial period. Various 
 supposed indications of his presence in " Inter-glacial " Glacial, 
 Pliocene, and even Miocene deposits have proved on examina- 
 tion to be unreliable. America has recently put forth claims 
 to have been inhabited by man in the Pliocene, on the faith 
 of remains found in auriferous gravels in the West. But the 
 facts that the implements and bones found are modern in 
 type, that the gravels were deeply mined by the Indians, 
 and that the objects found, as mortars for dressing gravel, etc., 
 are in many cases such as they would be likely to leave in their 
 excavations, have discredited these supposed discoveries. Still 
 more recently, chipped flints found in gravels in New Jersey, 
 by Abbott, have been supposed to carry back the Indians of 
 the East coast to the Glacial period. It is evident, however, from 
 the description of these deposits by the late Mr. Belt and by 
 Professor Cook, director of the Survey of New Jersey, that 
 they are really Post-glacial, that their age must be estimated 
 by study of the local conditions, and that there is no good 
 ground for correlating them with the upper members of the 
 true Glacial drift to the northwards, with which they had been 
 somewhat rashly identified. Irrespective of the doubtful 
 character of many if not all of the so-called implements, the 
 deposits in which they are found is confessedly not a product 
 of the ice of the Glacial period proper, whether that was, as 
 some maintain, a period of land glaciation as far south as New 
 Jersey or not. It belongs to a time of denudation by water, 
 aided perhaps by floating ice, and is not necessarily older than 
 the river gravels of the Somme, which, like it, contain boulders 
 and imply conditions of torrential action and climate which 
 have long since passed away. If, however, these imple- 
 ments are genuine, they would imply the presence of Palaeo- 
 cosmic or Antediluvian man in America. This would in itself 
 be an important discovery. 
 
THE ADVENT OF MAN. 239 
 
 For the present, therefore, man is geologically a Post- 
 glacial species, and there is nothing unreasonable in suppos- 
 ing that he dates no farther back, since several animals his 
 contemporaries are in the same case ; and by supposing him to 
 have originated after the Glacial age we avoid the difficulties 
 attendant on his survival of that great revolution. The only 
 necessity for supposing an earlier appearance arises from the 
 requirements of the hypothesis of evolution. Those, however, 
 who hold this theory, may with Haeckel take refuge in that 
 shadowy continent supposed to have extended from Africa to 
 Australia, 1 and to have sheltered man in his transition from the 
 ape to humanity, in the Tertiary period. The name Lemuria is 
 taken from the Lemurs, supposed ancestors of the Apes, which 
 still haunt the margin of the Indian Ocean; but it may be 
 taken also in its old Latin sense of ghosts of the evil dead ; 
 and as we are not likely to obtain any more tangible evidence 
 of the old natives of Lemuria, perhaps we may hope that some 
 spiritualist may succeed in charming them from the vasty deep 
 for our enlightenment. Should this be so, it is to be hoped 
 that no "drum ecclesiastic " will be beaten to drive them away 
 till they have revealed all they can tell. 
 
 It may be well to add that, in addition to the negative evi- 
 dence, there is at least one positive evidence of the recent 
 origin of man which has been well urged by Le Conte. It is 
 this : animals have continued long in geological time in the 
 inverse ratio of their rank. Some Mesozoic protozoa still 
 survive. So do many early Tertiary mollusks. But the mammals 
 are of much less duration. No living species goes back 
 farther than the Pliocene. Few extend farther than the 
 Glacial age. On the same principle it is not to be expected 
 that man, the highest of all animals, should extend far back in 
 geological time. 
 
 1 The actual reason for belief in the past existence of land in the basin 
 of the Indian Ocean is found in the close relationship of forms of life 
 found in Madagascar, Southern Asia, and Australia. 
 
240 THE CHAIN OF LIFE. 
 
 Accepting the Post-glacial age as that of the advent of 
 man, it may be interesting to ask what we know of the condi- 
 tion of our continents when he appeared. In Western Asia, 
 in Europe, except in its more northern portions, and it would 
 now seem also in America, man had been introduced at a 
 time closely following the emergence of the land from the 
 Glacial sea. At this time the land area of both continents was 
 larger than it is at present, and the character of the fauna 
 shows that much of the surface was occupied with great steppes 
 or prairies, over which migration would be easy; while there 
 were probably connections by land or chains of islands be- 
 tween the continents of the northern hemisphere. The land 
 animals of the continents were more numerous and of greater 
 stature than at present. Several species of elephants (Fig. 186) 
 and a rhinoceros roamed over the plains. The formidable 
 Elasmotherium (Fig. iSy), 1 an animal allied to the rhinoceros, 
 but more fleet and active, and of immense size, inhabited Asia 
 and Europe. Hippopotami, wild horses, the gigantic Irish 
 stag, several species of wild cattle, and bisons of greater size 
 than their successors, haunted the streams and steppes. The 
 cave bear, the cave lion, the spotted hyaena, and possibly the 
 Mdchairodus, were among the beasts of prey even in the 
 temperate latitudes. The climate must have been a continental 
 one, ranging through considerable extremes ; but the con- 
 ditions favoured migration of animals on the great scale, so 
 as to avoid these extremes, and hence species of types now 
 comparatively restricted enjoyed a wide distribution. 
 
 To establish themselves in such a world, the primitive men 
 must have been no puny race, either in mind or body, and they 
 must have been sheltered in some Eden of plenty and com- 
 parative safety till, by increase of numbers, invention of 
 weapons and implements, and domestication of useful animals, 
 they became able to cope with the monarchs of the waste. 
 
 1 Traditions of this animal, a veritable primaeval unicorn, are said still 
 to exist in Siberia. 
 
THE ADVENT OF MAN. 
 
 241 
 
242 
 
 THE CHAIN OF LIFE. 
 
 But this position once attained in the original seats of the 
 species, the wide continents presented great facilities for their 
 movements, and there were ample stores of food for wandering 
 tribes subsisting by the chase. 
 
 With such views the skeletons of the most ancient known 
 
 men l fully accord. They indicate 
 a people of great stature, of power- 
 ful muscular development, espe- 
 cially in the lower limbs, of large 
 brain, indicating great capacity and 
 resources (Fig. 188), but of coarse 
 Turanian features, like those of 
 the tribes that now roam over the 
 plains of Northern Asia (Fig. 
 189). They used flint and bone 
 implements, which they manufac- 
 tured with much skill (Figs. 190, 
 191). They were probably clothed 
 in dressed skins, ornamented with 
 embroidery, in the manner of the 
 North American Indians. They 
 used shells and carved bones as 
 ornaments. Recent discoveries 
 at Soloutre, in France, render it 
 probable that some of the tribes 
 had tamed the horse, and resided 
 in fortified villages. They buried 
 their dead with offerings, indica- 
 ting a belief in immortality. These 
 Post-glacial men are certainly 
 known as yet only in Europe and Western Asia; and we 
 cannot therefore determine if they represent the average man 
 of the period. There were in Belgium and other parts of 
 Europe, men of smaller stature and of lower cranial type, 
 1 As, for instance, those of Cro-Magnon, and Mentone, and Engis. 
 
 FIG. 187. Tooth of Elasmotherium. 
 Grinding surface, natural size. 
 Siberia. From Nature. 
 
THE ADVENT OF MAN. 
 
 243 
 
 contemporary or nearly so with the higher race. There may 
 have been fruit-eating or agricultural peoples in the more genial 
 and fertile lands of the east and south. The conditions above 
 sketched are, I think, fairly deducible from the facts stated by 
 Christy and Lartet, Dupont, Riviere, Dawkins, and others, who 
 have studied the remains of these early men, the Palaeolithic 
 men of some writers, or the men of the Mammoth age, and 
 whom I have elsewhere named Palaeocosmic men, as a term 
 less objectionable than those founded on implements not 
 confined to any age, or animals which may have long antedated 
 man. Recent discoveries 
 in the caves of Spy in 
 Belgium, 1 taken in con- 
 nection with the previous 
 discoveries of Schmeiiing 
 and Dupont, seem to 
 show the existence in 
 that country of men of 
 the low-browed Neander- 
 thal or Canstadt type 
 (Fig. 189 third outline), 
 perhaps locally preceding 
 but perhaps contempo- 
 raneous with, the larger 
 and better developed 
 
 men of the Cro-Magnon type (Fig. 189 first outline). These two 
 types are, however, allied, and there are intermediate forms, so 
 that they are to be regarded as two races of Palaeocosmic men 
 not more dissimilar than we find in cognate rude races at present. 
 They were succeeded in Western Europe by a smaller and 
 less elevated race, identical apparently with the modern Lapps 
 and Basques, and in whose time the mammoth and many large 
 animals had disappeared, Europe had become clad with dense 
 forests, and the reindeer had extended his range far to the 
 
 1 De Puyot and Lohert, Namur, 1887. 
 
 R 2 
 
 FIG. 188. Engis Skull. Reduced. After Lyell. 
 The Skull of one of the Men of the Mammoth age. 
 
24+ 
 
 THE CHAIN OF LIFE. 
 
 south, while the land of our continents had become narrowed 
 to its present limits, or even less. The cause of these changes 
 must have been physical, and to some extent cataclysmal ; and 
 its wide-spread and effectual character is shown by the fact 
 that it exterminated so many animals of both continents which 
 had survived the Glacial age. Similar testimony is borne by 
 
 FIG. 189. Outlines of Three Prehistoric European Skulls compared with an American 
 Skull from Hochelaga. 
 
 Outer outline, Cro-Magnon Skull. Second outline, Engis Skull. Third outline (dotted), 
 Neanderthal Skull. Inner figure, Hochelagan Skull on a smaller scale. 
 
 the occurrence of the implements and remains of Falaeocosmic 
 men in gravels and in diluvial clays in caverns, and by the 
 changes of level and deep erosions of valleys that are referable 
 to the close of the Palaeocosmic age. The most probable 
 agencies in this revolution were subsidences of the land, 
 accompanied with climatal changes ; but the precise nature and 
 extent of these is still unknown ; and the prevalent tendency 
 
THE ADVENT OF MAN. 
 
 245 
 
 on the part of geologists to stretch the doctrine of uniformity, 
 so valuable within proper limits, to the absurd extreme of 
 excluding all changes not exemplified even in amount in the 
 modern period, will probably for some time prevent any 
 adequate conception of them. 
 
 It would be premature to correlate what is yet known of the 
 Palaeocosmic age with historical periods ; but the tendency of 
 the facts accumulated is, I think, toward the identification of 
 the Palaeocosmic men with the Antediluvians ; and their Neo- 
 cosmic successors, whether of the 
 reindeer age, of the Danish shell- 
 mounds, or the Swiss lake habita- 
 tions, with Postdiluvian and still 
 existing tribes. 
 
 After what has been already said, 
 it will be unnecessary to dwell upon 
 the characteristics of the first race 
 of men known to us. They were 
 rude and uncivilised, in so far as 
 outward appliances are concerned ; 
 but they are confessedly altogether 
 men, and in no respect akin to apes, 
 and their volume of brain is rather 
 greater than that of the average 
 European of to-day ; so that they 
 must have had quite as much natural sagacity and capacity for 
 culture, and, like the modern and historic Turanian nations, 
 they were probably superior to the average European in the 
 instinct for art and construction. Thus if we suppose these 
 men derived from apes by any process of gradual change, 
 we must look for their brute ancestors, not in the Pliocene or 
 Miocene, but in the Eocene itself. This causes us to recur 
 to the doctrine of critical periods, when many species were 
 introduced together, alternating with periods of decay and ex- 
 tinction. Post-glacial man appears at the end of a time of 
 
 FIG. 190. Flint Implement found 
 in Kent's Cavern, Torquay, under 
 four feet of cave mud and one foot 
 of stalagmite. After Pengelly. 
 
246 
 
 THE CHAIN OF LIFE. 
 
 sifting and trial, a time in which a vast number of species suc- 
 cumbed to great physical reverses. No very great number of 
 species came in with him, and in the early period of his his- 
 tory there was a decadence or destruction either by the 
 diluvial cataclysm or gradually. Out of ninety-eight species 
 of mammals contemporary with early man in Europe, forty- 
 one are wholly or locally extinct, and none 
 have been introduced except those brought 
 by man himself. Thus man stands alone, 
 the grand product of his period and a lord of 
 creation, for whom great preparatory changes 
 were made, and multitudes of lower animals 
 swept away to make room for him. Accord 
 ing to our sacred Scriptures, this change is still 
 imperfect, and great additional ameliorations 
 would have taken place but for a moral 
 catastrophe not within the domain of geology 
 the fall of man. If we identify the Palaeo- 
 cosmic men with the Antediluvians of the 
 same venerable record, the roving tribes 
 whose remains are known to us represent 
 that part of the race of Cain of whom Jubal 
 was the father, the nomads dwelling in tents, 
 
 Vas distinguished from the settled agricultural 
 peoples. In this case, also, the catastrophe 
 which destroyed these rude and lawless men 
 was that which culminated in the deluge of 
 
 FIG. 191. Bone Har- .,,,., . 
 
 poon (Paheocosmic), Noah, which may represent the extinction of 
 
 from Perigord ., ,. ., -, * .1 . 
 
 irom 
 Cavern. 
 
 the last great body of this primitive race, 
 whose arts, handed down to the physically 
 
 inferior men of Postdiluvian times, astonish us by their early 
 
 development in Chaldsea and in Egypt. 
 
 If man is so recent geologically, he may still be very old 
 
 historically; and the question remains, Have we any facts 
 
 bearing on the absolute antiquity of man ? For the properly 
 
THE ADVENT OF MAN. 247 
 
 historical aspect of this question, I may refer to the excellent 
 work of Canon Rawlinson on the Origin of Nations?- which 
 shows conclusively that the historic origin of all the great 
 nations of antiquity extends backward less than 4,400 years 
 from our time. Beyond this we have, however, the Palaeo- 
 cosmic or Antediluvian men; and their extension backward 
 seems limited geologically only by the close of the Glacial 
 period, while many hold that the Genealogy in Genesis does 
 not require us to limit very narrowly their antiquity. The date 
 of the Glacial period is, however, at present very uncertain. 
 On the one hand, some geologists, like Lyell, have supposed 
 it may be as far back as 200,000 years ago. Others, like 
 Croll, are contented with the more moderate estimate of 80,000 
 years. On the other hand, the calculations of Andrews, based 
 on the recession of the American lakes, those of Winchell on the 
 recession of the Falls of St. Anthony, and the recent surveys of 
 the recession of the Falls of Niagara, reduce the time to 
 from 7,000 to 10,000 years. It is impossible in the present 
 state of knowledge to settle these disputes; but one may 
 refer in the sequel to some of the evidences which have 
 been adduced in favour of great antiquity. Since the pub- 
 lication of the second edition of this work Prof. Prestwich, in 
 a paper read before the Geological Society, 2 has brought for- 
 ward other reasons which induce him to conclude that the close 
 of the Glacial epoch occurred "from 8,000 to 10,000 years 
 since." It is true, he admits, on geological evidence still in 
 dispute, that man may have existed in Europe before that time, 
 and he also admits, on historical, not geological evidence, the 
 existence of " Neolithic " man in Asia, "at an earlier date than 
 4,000 E.G." Still the repudiation, by so good an authority, of 
 the exaggerated antiquity which it has been the fashion, since 
 the rise of Darwinian evolution, to assign to man, contrary to 
 the geological evidence, is a satisfactory indication of a return 
 to more rational views ; and when geologists get rid of the 
 1 Religious Tract Society, 1878. * May, 1887. 
 
248 THE CHAIN OF LIFE. 
 
 fiction of a continental ice-sheet, still farther progress in this 
 direction may be expected. 
 
 We may, I think, at once take it for granted, that none of 
 the Neocosmic races date farther back than the origin of the 
 great eastern nations. There are certainly no geological evi- 
 dences requiring a greater antiquity, for in their time the land 
 had attained to its present configuration, and the changes which 
 have occurred in the succession of forests and the growth of 
 peat are such as our experience in America shows to be 
 possibly quite modern. There is besides no doubt that these 
 people, from the Reindeer men of France and Belgium to the 
 people of the Swiss lakes, are modern races, whose descendants 
 still live in Europe. We can thus limit our inquiry to the 
 Palaeocosmic men; and with respect to them we know only 
 what may be gathered from a consideration of the physical 
 changes which have occurred since they lived. 
 
 In Europe a great number of considerations have been adduced 
 as evidence of their high antiquity ; and these deserve careful 
 attention, though I think it will be found that they are all liable 
 to serious objections or great abatements on geological grounds. 
 
 (1) The occurrence of human remains with those of animals 
 now extinct affords no certain evidence of antiquity. Ad- 
 mitting that human remains are found along with those of the 
 mammoth in Europe, and with those of the mastodon in 
 America, the question remains, How late did these species 
 survive ? In Europe we know that several large animals now 
 extinct existed up to comparatively modern times. This is the 
 case with the Irish deer (Megaccros), the urus, the aurochs, 
 and the reindeer, in temperate Europe. How long previously 
 the mammoth or the hairy rhinoceros disappeared we do not 
 know, but need not suppose the time very long. 
 
 (2) The accumulation of sediment or of stalagmite over 
 human remains in caverns is not necessarily indicative of very 
 great antiquity. We know that in favourable circumstances 
 mud, sand, and gravel may be rapidly deposited in caves by land 
 
THE ADVENT OF MAN. 
 
 249 
 
 floods or river inundations, and that debris of various sorts 
 accumulates in such places from decay of rock and vegetable 
 and animal agencies. The deposition of stalagmite is also very 
 variable in its rate ; and the fact that it is being very slowly 
 deposited in any cave now does not prove that more rapid 
 deposition may not have taken place formerly. Dawkins and 
 others have ascertained a rate of a quarter of an inch per 
 annum in some caverns ; and this would allow the stalagmite 
 crust of Kent's cave, for which an antiquity of half a million of 
 years has been claimed, to have been formed in a thousand years. 
 (3) The erosion of river valleys to great depths since the 
 
 FIG. 192. Sketch of a Mammoth, carved on a portion of a Tusk of the same Animal 
 (Lartet). 
 
 Glacial period fails to establish the great antiquity of the caves 
 left on their sides or the high level gravels of their banks. 
 Throughout the northern hemisphere, the river valleys are of 
 old date, and were merely filled with loose detritus in the Glacial 
 age. The sweeping out of this dtbris would be a rapid process, 
 more especially when changes of level were occurring, and 
 when the rainfall was greater than at present. Besides, as Croll 
 has well remarked, the actual configuration of our continents, 
 the amount of drift still remaining, and the imperfect manner 
 in which the river valleys have been cleared out, all testify to 
 
250 THE CHAIN OF LIFE. 
 
 the comparative recency of the Glacial period. 1 These con- 
 siderations would, indeed, materially reduce the antiquity 
 which he claims on astronomical grounds for the ice age. 
 
 (4) The growth of peat and the deposition of silt are very 
 deceptive as indications of great antiquity. For instance, 
 accurate observations made by a French engineer in the con- 
 struction of docks at St. Nazaire, 2 show that in 1,600 years the 
 Loire had deposited over Gallo-Roman remains six metres of 
 mud. Relics of the Bronze age occur below these at a depth 
 indicating 500 years previously as their date ; and the beginning 
 of the modern deposit of the Loire would, on the same evidence, 
 be only 6,000 years ago. Hilgard's observations on the delta of 
 the Mississippi in like manner tend greatly to reduce our esti- 
 mates of the time occupied in the deposit of the modern silt of 
 that river. The peat deposit at Abbeville, at the mouth of the 
 Somme, has been supposed to have required 30,000 years 
 for its formation. But this estimate was based upon the 
 present rate of growth ; and, as Andrews has shown, the fact 
 admitted by Boucher de Perthes, that birch stems three feet 
 high stand in this peat, implies a much more rapid rate, 
 which is also proved by the depth at which Roman remains 
 have been found. In like manner the Scandinavian peats, to 
 which a fabulous antiquity has been ascribed, have been proved 
 to be comparatively modern by the depths at which metallic 
 works of art are found in them. 
 
 (5) The paucity of remains of Palaeocosmic men in Europe, 
 with their wide distribution, indicate that their sojourn was not 
 long, or that the population was very small and much scattered. 
 Even in a few thousands of years, an active and vigorous people, 
 living in a country well supplied with food, must have multiplied 
 greatly, and must have left considerable remains. On the theory 
 that these men inhabited Europe even for 2,000 years, we have to 
 
 1 Climate and Time, a work in which these and other matters relating to 
 the Glacial period are very well discussed. 
 
 2 Kimber, quoted by Southall. 
 
THE ADVENT OF MAN. 251 
 
 suppose that the greater part of their remains have been swept 
 away, or remain under the waters, or buried out of sight in 
 diluvial sediments. 
 
 (6) Much importance has been attached to the early works 
 and high culture of Egypt and Chaldsea, as evidence of vast 
 time during which arts were growing from a supposed rude 
 stone age. But it must be observed that no such period is 
 known to antedate civilisation in the East, and that if the early 
 empires were established by survivors of the Deluge, they must 
 have brought with them the culture of Antediluvian times. 
 Farther, the notion of men emerging from a half-brutal state, 
 and from the use of the rudest implements, is purely conjectural 
 and not supported by facts. In America, where the semi- 
 civilised agricultural races are unquestionably the oldest, the 
 rudest possible implements were used by these partially civilised 
 agricultural people along with polished stone and metal ; and 
 Schliemann has shown that a rude stone age succeeded the 
 civilisation of Troy, and this at a time when Phoenicia and 
 Egypt were at the height of their civilisation. Such facts, 
 which might fill volumes, show how little value is to be attached 
 to supposed ages of rough and polished stone. 
 
 (7) The difficulties attending the establishment of geological 
 dates for deposits like those containing the remains of men are 
 very great. They are altogether superficial and local, not wide- 
 spread marine beds in which a distinct order of superposition 
 can be clearly traced. They are not easily separated from the 
 glacial beds below, or from those above which have been modi- 
 fied by human agency, by land-floods, or by landslips. Thus 
 the application of geological criteria of age to them is very 
 difficult and uncertain. Evidence of this could easily be given, 
 in the many errors which have been promulgated, and which 
 have had to be retracted by their authors, or have been 
 disproved by the observations of others. For example, no 
 country was at one time richer in supposed evidences of the 
 antiquity of man than Scandinavia ; but Professor Torell, the 
 
252 THE CHAIN OF LIFE. 
 
 director of the Geological Survey of Sweden, has recently made a 
 careful re-examination of the facts, and has found that there is 
 no evidence whatever of the existence of man in Scandinavia 
 before the Neolithic or polished stone age. There are, how- 
 ever, -evidences of considerable changes of level since that 
 time, and it would seem even since the twelfth century of our 
 era. The remarkable and seemingly inexcusable errors of 
 observation referred to in Professor Torell's memoir, should 
 enforce a caution on geologists as to the uncertainties of such 
 evidence. Lyell sifted the testimony bearing on this subject 
 with great care in the first edition of his Antiquity of Man. 
 In later editions he had to make large abatements, and now 
 much of the evidence in the latest edition would have to be 
 withdrawn or otherwise applied. 
 
 From all these considerations the conclusion is obvious that 
 while we have no certain data for assigning a definite number of 
 years to the residence of man on the earth, we have no geo- 
 logical evidence for the rash assertion often made that in com- 
 parison with historical periods the date of the earliest races of 
 men recedes into a dim, mysterious, and measureless antiquity. 
 On the basis of that Lyellian principle of the application of 
 modern causes to explain past changes, . which is the stable 
 foundation of modern geology, we fail to erect any such 
 edifice as the indefinite antiquity of man, or to extend this 
 comparatively insignificant interval to an equality with the long 
 aeons of the preceding Tertiary. The demand for such in- 
 definite extension of the history of man rests not on geological 
 facts, but on the necessities of hypotheses which, whatever 
 their foundation, have no basis in the discoveries of that science, 
 and are not required to account for the sequence which it 
 discloses. 
 
CHAPTER XL 
 
 REVIEW OF THE HISTORY OF LIFE. 
 
 
 
 WHAT general conclusions can we reach as to this long 
 and strange history of the progress of life on our 
 planet ? Perhaps the most comprehensive of these is that the 
 links in the chain of life, or rather in its many chains, are not 
 scattered and disunited things, but members of a great and 
 complex plan ; and that when we discern their combinations 
 and their pattern, we find them not only orderly and symme- 
 trical, but all tending to one point and bound to one central 
 object, even the throne of the Eternal. It must also appear 
 evident that the original plan of nature, both in the animal and 
 vegetable worlds, was too vast to be realised at one time on a 
 globe so limited as ours, but had to be distributed in time 
 as well as in space, thus realising the idea of time-worlds : 
 successive aeons in which, one after the other, the work of 
 creation could rise to successive stages of perfection and com- 
 pleteness till it culminated in man. All this is sufficiently 
 plain on the theistic view of nature, and may suffice for those 
 who reverently regard the God of nature as the Father of their 
 own spirits. But there are others who ask further questions. 
 Do we know anything of the secondary causes and origin of 
 life, of the manner of its introduction and advance, of the laws 
 of its succession ? 
 
254 THE CHAIN OF LIFE. 
 
 As to the first of these questions, it is certain that, up to 
 this time, the origination of the living being from the non- 
 living is an inscrutable mystery. No one has witnessed this 
 change, or has been able to effect it experimentally. Nor have 
 we any direct evidence of the origination of one specific type 
 from another. Such reasonings as assume the possibility of 
 these things, or on analogical grounds assert their probability, 
 belong rather to the domain of philosophical speculation than 
 to science. As to the laws of the succession of life, however, 
 it is possible to learn something from the sequence of facts 
 as already ascertained ; and though much remains to be dis- 
 covered, there are a few leading statements on this subject 
 which can already be made with safety. 
 
 Unity and uniformity, within the limits imposed by progress 
 and increasing complexity, can be affirmed of the whole 
 process. From the dawn of life to the present time the 
 great laws of physical nature which operate on animals and 
 plants have been uniform. These stable laws have regulated 
 the action of the outer world on organisms. The plans of 
 structure of these organisms laid down at the first have been 
 followed throughout. Thus the succession of life presents 
 nothing fortuitous or arbitrary, but a continuous plan carried 
 out uniformly in time and space, with certain materials of fixed 
 properties, and with certain structures predetermined from the 
 first. There is, for example, a great sameness of plan throughout 
 the whole history of the marine invertebrate life of the Palaeo- 
 zoic. If we turn over the pages of an illustrated text-book of 
 geology, or examine the cases or drawers of a collection of 
 fossils, we shall find extending through every succeeding forma- 
 tion, representative forms of Crustaceans, Mollusks, and Corals, 
 in such a manner as to indicate that in each successive period 
 there has been a reproduction of the same type with modifica- 
 tions ; and if the series is not continuous, this appears to be 
 due to lack of specimens, or to abrupt physical changes ; since 
 sometimes, where two formations pass into each other, we find 
 
REVIEW OF THE HISTORY OF LIFE. 255 
 
 a gradual change in the fossils by the dropping out and intro- 
 duction of species one by one. Thus in the whole of the 
 great Palaeozoic period, both in its fauna and flora, we have 
 a continuity and similarity of a most marked character. 
 
 There is, indeed, nothing to preclude the supposition that 
 many forms reckoned as species are really only race modifica- 
 tions. My own provisional conclusion, based on the study of 
 Palaeozoic plants, published many years ago, 1 is that the general 
 law will be found to be the existence of distinct specific types 
 independent of each other, but liable in geological time to 
 minor modifications, which have often been regarded as distinct 
 species. 
 
 While this unity of successive faunae at first sight presents 
 an appearance of hereditary succession, it loses much of this 
 character when we consider the number of new types in- 
 troduced without apparent predecessors, or ceasing without 
 successors, and the almost changeless persistence of other 
 types ; the necessity that there should be similarity of type in 
 successive faunae on any hypothesis of a continuous plan ; 
 and, above all, the fact that the recurrence of representative 
 species or races in large proportion marks times of decadence 
 rather than of expansion in the types to which they belong. To 
 return to a later period, this is very manifest in that singular 
 resemblance which obtains between the modern mammals of 
 South America and Australia and their immediate fossil pre- 
 decessors the phenomenon being here manifestly that of 
 decadence of large and abundant species into a few depau- 
 perated representatives. This will be found to be a very 
 general law, elevation being accompanied by the abrupt 
 appearance of new types, and decadence by the apparent 
 continuation of old species, or modifications of them. 
 
 This resemblance with difference in successive faunae also 
 connects itself very directly with the successive elevations and 
 depressions of our continental plateaus in geological time. 
 1 Report on Devonian Plants of Canada, 1871. 
 
256 THE CHAIN OF LIFE. 
 
 Every great Palaeozoic limestone, for example, indicates a 
 depression with succeeding elevation. On each elevation 
 marine animals were driven back into the ocean, and on each 
 depression swarmed in over the land, reinforced by new 
 species, either then introduced or derived by migration from 
 other localities. In like manner on every depression, land 
 plants and animals were driven in upon insular areas, 
 and on re-elevation again spread themselves widely. Now I 
 think it will be found to be a law here that periods of expan- 
 sion were eminently those of introduction of new specific types, 
 and periods of contraction those of extinction, and also of 
 continuance of old types under new varietal forms. It must 
 also be borne in mind that all the leading types of invertebrate 
 life were early introduced, that change within these was neces- 
 sarily limited, and that elevation could take place mainly by 
 the introduction of the vertebrate orders. So in plants, Cryp- 
 togams early attained their maximum as well as Gymnosperms, 
 and elevation occurred in the introduction of Phaenogams. 
 
 Another allied fact is the simultaneous appearance of like 
 types of life in one and the same geological period, over 
 widely separated regions of the earth's surface. This strikes 
 us especially in the comparatively simple and homogeneous 
 life-dynasties of the Palaeozoic, when for example we find the 
 same types of Silurian Graptolites, Trilobites and Brachiopods 
 appearing simultaneously in Australia, America, and Europe. 
 Perhaps in no department is it more impressive than in the 
 introduction in the Devonian and Carboniferous ages of that 
 grand cryptogamous and gymnospermous flora which ranges 
 from Brazil to Spitzbergen, and from Australia to Scotland, 
 accompanied in all by the same groups of marine invertebrates ; 
 or in the like wholesale production of modern types of trees in 
 the Cretaceous. Such facts may depend either on that long 
 life of specific types which gives them ample time to spread 
 to all possible habitats, before their extinction ; or on some 
 general law whereby the conditions suitable to similar types of 
 
REVIEW OF THE HISTORY OF LIFE. 257 
 
 life emerge at one time in all parts of the world. Both causes 
 may be influential, as the one does not exclude the other, and 
 there is reason to believe that both are natural facts. Should 
 it be ultimately proved that species allied and representative, 
 but distinct in origin, come into being simultaneously every- 
 where, we shall arrive at one of the laws of creation, and one 
 probably connected with the gradual change of the physical 
 conditions of the world. 
 
 A closely related truth is the periodicity of introduction of 
 species. They come in by bursts or flood-tides at particular 
 points of time, while these great life-waves are followed and 
 preceded by times of ebb in which little that is new is being 
 produced. We labour in our investigation of this matter under 
 the disadvantage that the modern period is evidently one of 
 the times of pause in the creative work. Had our time been 
 that of the early Tertiary or early Mesozoic, our views as to 
 the question of origin of species might have been very differ- 
 ent It is a striking fact, in illustration of this, that since the 
 Glacial age no new species of mammal can be proved to have 
 originated on our continents, while a great number of large 
 and conspicuous forms have disappeared. It is possible that 
 the proximate or secondary causes of the ebb and flow of 
 life-production may be in part at least physical; but 
 other and more important efficient causes may be behind 
 these. In any case these undulations in the history of life 
 are in harmony with much that we see in other departments 
 of nature. 
 
 It results from the above and the immediately preceding 
 statement that specific and generic types enter on the stage 
 in great force, and gradually taper off toward extinction. They 
 should so appear in the geological diagrams made to illustrate 
 the succession of life. This applies even to those forms of life 
 which come in with fewest species and under the most humble 
 guise. What a remarkable swarming, for example, there must 
 have been of Marsupial Mammals in the early Mesozoic ; and 
 
 s 
 
258 THE CHAIN OF LIFE. 
 
 in the Coal formation the only known Pulmonates, four or 
 five in number, belong to as many generic types. 
 
 I have already referred to the permanence of certain species 
 in geological time. I may now place this in connection with 
 the law of origination and more or less continuous transmission 
 of varietal forms. I may, perhaps, best illustrate this in con- 
 nection with a group of species with which I am very familiar, 
 that which came into our seas at the beginning of the Glacial 
 age, and still exists. With regard to their permanence, it can 
 be affirmed that the shells now elevated in Wales to 1,200 and 
 in Canada to 600 feet above the sea, and which lived before 
 the last great revolution of our continents, a period vastly 
 remote as compared with human history, differ in no tittle from 
 their modern successors after thousands or tens of thousands 
 of generations. It can also be affirmed that the more variable 
 species appear under precisely the same varietal forms then as 
 now, though these varieties have changed much in their local 
 distribution. The real import of these statements, which might 
 also be made with regard to other groups well known to palae- 
 ontologists, is of so great significance that it can be realised 
 only after we have thought of the vast time and numerous 
 changes through which these humble creatures have survived. 
 I may call in evidence here a familiar British and American 
 animal, the common sand clam, Mya arenaria, and its relative, 
 Mya truncata, which now inhabit together all the northern 
 seas ; for the Pacific specimens, from Japan and California, 
 though differently named, are undoubtedly the same. Mya 
 truncata appears in Europe in the older Pliocene, and was 
 followed by M. arenaria a little later. Both shells occur in 
 the Pleistocene of America, and their several varietal forms 
 had then already developed themselves, and remain the 
 same to-day ; so that these humble mollusks, littoral in their 
 habits, and subjected to a great variety of conditions, have 
 continued, perhaps for one or two thousand centuries, to con- 
 struct their shells precisely as at present. Nor are there any 
 
REVIEW OF THE HISTORY OF LIFE. 259 
 
 indications of a transition between the two species. Similar 
 statements may be made with regard to other mollusks of the 
 Pliocene and Modern periods, and there are even species 
 which extend unchanged from the early Eocene. Nor is it 
 impossible that some modern bivalves of the Brachiopod 
 group may be scarcely modified descendants even of Palaeozoic 
 species. 
 
 Perhaps some of the most remarkable facts in connection 
 with the permanence of species and varietal forms are those 
 furnished by that magnificent flora which burst in all its 
 majesty on the American continent in the Cretaceous period, 
 and still survives among us even in some of its specific types, 
 I say survives ; for we have but a remnant of its forms living, 
 and comparatively little that is new has probably been added 
 since. Take, for example, the facts stated in Chapter VIII. 
 as to the continuance to the present time of species of plants 
 introduced in the Cretaceous and Eocene, and which thus came 
 in at the very time when the great Mesozoic reptiles were 
 decaying or had just disappeared, and when the placental 
 mammals were being introduced. Some of these plants must 
 have propagated themselves unchanged for half a million of 
 years. 
 
 Plants and the lower tribes of animals are, however, more 
 permanent than the higher animals ; and a strange contrast 
 is afforded to the foregoing examples of persistence by the 
 repeated revolutions that have affected vertebrate life since 
 the Mesozoic age. Yet even in the case of vetebrates there 
 seems to have been little change, except in the extinction of 
 species, since the Pliocene period. 
 
 In conclusion of this review, can we formulate a few of the 
 general laws, or perhaps I had better cajl them the general 
 conclusions respecting life, in which all palaeontologists may 
 agree ? Perhaps it is not possible to do this at present satis- 
 factorily, but the attempt may do no harm. We may, then, 
 I think, make the following affirmations : 
 
 S 2 
 
26o THE CHAIN OF LIFE. 
 
 (1) The existence of life and organisation on the earth is not 
 eternal, or even coeval with the beginning of the physical uni- 
 verse, but may possibly date from Laurentian or immediately 
 pre-Laurentian times. 
 
 (2) The introduction of new species of animals and plants 
 has been a continuous process, not necessarily in the sense of 
 derivation of one species from another, but in the higher sense 
 of the continued operation of the cause or causes which intro- 
 duced life at first. This, as already stated, I take to be the 
 true theological or Scriptural as well as scientific idea of what 
 we ordinarily and somewhat loosely term creation. 
 
 (3) Though thus continuous, the process has not been uni- 
 form ; but periods of rapid production of species have alter- 
 nated with others in which many disappeared and few were 
 introduced. This may have been an effect of physical cycles 
 reacting on the progress of life. 
 
 (4) Species, like individuals, have greater energy and vitality 
 in their younger stages, and rapidly assume all their varietal 
 forms, and extend themselves as widely as external circum- 
 stances will permit. Like individuals, also, they have their 
 periods of old age and decay, though the life of some species 
 has been of enormous duration in comparison with that of 
 others ; the difference appearing to be connected with degrees 
 of adaptation to different conditions of life. 
 
 (5) Many allied species, constituting groups of animals and 
 plants, have made their appearance at once in various parts 
 of the earth, and these groups have obeyed the same laws 
 with the individual and the species in culminating rapidly, and 
 then slowly diminishing, though a large group once introduced 
 has rarely disappeared altogether. 
 
 (6) Groups of species, as genera and orders, do not usually 
 begin with their highest or lowest forms, but with interme- 
 diate and generalised types, and they show a capacity for both 
 elevation and degradation in their subsequent history. 
 
 (7) The history of life presents a progress from the lower to 
 
REVIEW OF THE HISTORY OF LIFE. 261 
 
 the higher, and from the simpler to the more complex, and 
 from the more generalised to the more specialised. In this 
 progress new types are introduced, and take the place of the 
 older ones, which sink to a relatively subordinate place, and 
 become thus degraded. But the physical and organic changes 
 have been so correlated and adjusted that life has not only 
 -always maintained its existence, but has been enabled to assume 
 more complex forms, and that older forms have been made to 
 prepare the way for newer, so that there has been on the whole 
 a steady elevation culminating in man himself. Elevation and 
 specialisation have, however, been secured at the expense of 
 vital energy and range of adaptation, until the new element of 
 a rational and inventive nature was introduced in the case 
 of man. 
 
 (8) In regard to the larger and more distinct types, we cannot 
 find evidence that they have, in their introduction, been pre- 
 ceded by similar forms connecting them with previous groups ; 
 but there is reason to believe that many supposed representa- 
 tive species in successive formations are really only races or 
 varieties. 
 
 (9) In so far as we can trace their history, specific types are 
 permanent in their characters from their introduction to their 
 extinction, and their earlier varietal forms are similar to their 
 later ones. 
 
 (10) Palaeontology furnishes no direct evidence, perhaps never 
 can furnish any, as to the actual transformation of one species 
 into another, or as to the actual circumstances of creation of a 
 species, but the drift of its testimony is to show that species 
 come in per saltum, rather than by any slow and gradual 
 process. 
 
 (u) The origin and history of life cannot, any more than the 
 origin and determination of matter and force, be explained on 
 purely material grounds, but involve the consideration of power 
 referable to the unseen and spiritual world. 
 
 Different minds may state these principles in different ways, 
 
262 THE CHAIN OF LIFE. 
 
 but I believe that in so far as palaeontology is concerned, in 
 substance they must hold good, at least as steps to higher 
 truths. And now I may be permitted to add that we should 
 be thankful that it is given to us to deal with so great questions, 
 and that in doing so deep humility, earnest seeking for truth, 
 patient collection of all facts, self-denying abstinence from 
 hasty generalisations, forbearance and generous estimation with 
 regard to our fellow-labourers, and reliance on that Divine Spirit 
 which has breathed into us our intelligent life, and is the source 
 of all true wisdom, are the qualities which best become us. 
 
 As we have traced onward the succession of life, reference 
 has been made here and there to the defects of those bold 
 theories of descent with modification which are held forth in 
 our time as the true bond of the links of the chain of life. It 
 must have been apparent that these theories, however specious 
 when placed in connection with a limited induction of facts 
 selected for the purpose of illustrating them, are very far from 
 affording a satisfactory solution of all difficulties. They can- 
 not perhaps be expected to take us back to the origin of 
 living beings ; but they also fail to explain why so vast 
 numbers of highly organised species struggle into existence 
 simultaneously in one age and disappear in another, why no 
 continuous chain of succession in time can be found gradually 
 blending species into each other, and why in the natural 
 succession of things degradation under the influence of ex- 
 ternal conditions and final extinction seem to be laws of 
 organic existence. It is useless here to appeal to the imper- 
 fection of the record or to the movements or migrations of 
 species. The record is now in many important parts too 
 complete, and the simultaneousness of the entrance of the 
 faunas and floras too certainly established, while the moving 
 of species from place to place only evades the difficulty. The 
 truth is that such hypotheses are at present premature, and that 
 we require to have larger collections of facts. Independently 
 of this, however, it would seem that from a philosophical 
 
REVIEW OF T^E HISTORY OF LIFE. 263 
 
 point of view all theories of evolution, as at present applied 
 to life, are fundamentally defective in being too partial in 
 their character; and this applies more particularly to those 
 which are " monstic " or " agnostic," and thus endeavour to 
 dispense with a Creative Will behind nature. It may be 
 instructive to illustrate from the facts developed in preceding 
 chapters this feature of most of the attempts at generalisation 
 on this subject. 
 
 First, then, these hypotheses are too partial, in their ten- 
 dency to refer numerous and complex phenomena to one 
 cause, or to a few causes only, when all trustworthy analogy 
 would indicate that they must result from many concurrent 
 forces and determinations of force. We have of late been 
 very familiar with those ingenious, not to say amusing, specula- 
 tions in which some entomologists and botanists have indulged 
 with reference to the mutual relations of flowers and haustellate 
 insects. Geologically the facts oblige us to begin with Cryp- 
 togamous plants and mandibulate insects ; and out of the 
 desire of insects for non-existent honey, and the adaptations of 
 plants to the requirements of non-existent suctorial apparatus, 
 we have to evolve the marvellous complexity of floral form 
 and colouring, and the exquisitely .delicate apparatus of the 
 mouths of haustellate insects. Now when it is borne in mind 
 that this theory implies a mental confusion on our part pre- 
 cisely similar to that which in the department of mechanics 
 actuates the seekers for perpetual motion, that we have not the 
 smallest tittle of evidence that the changes required have 
 actually occurred in any one case, and that the thousands of 
 other structures and relations of the plant and the insect have 
 to be worked out by a series of concurrent evolutions so 
 complex and absolutely incalculable in the aggregate that the 
 cycles and epicycles of the Ptolemaic astronomy were child's 
 play in comparison, we need not wonder that the common 
 sense of mankind revolts against such fancies, and that we are 
 accused of attempting to construct the universe by methods 
 
264 THE CHAIN OF LIFE. 
 
 that would baffle Omnipotence itself, because they are simply 
 absurd. In this aspect of them, indeed, such speculations are 
 necessarily futile, because no mind can grasp all the complexities 
 of even any one case, and it is useless to follow out an imaginary 
 line of development which unexplained facts must contradict 
 at every step. This is also no doubt the reason why all 
 recent attempts at constructing " Phylogenies " are so change- 
 able, and why no two experts can agree about almost any 
 of them. 
 
 A second aspect in which such speculations are too partial 
 is in the unwarranted use which they make of analogy. It is 
 not unusual to find such analogies as that between the em- 
 bryonic development of the individual animal and the succession 
 of animals in geological time placed on a level with that 
 reasoning from analogy by which geologists apply modern 
 causes to explain geological formations. No claim could be 
 more unfounded. When the geologist studies ancient lime- 
 stones built up of the remains of corals, and then applies the 
 phenomena of modern coral reefs to explain their origin, he 
 brings the latter to bear on the former by an analogy which 
 includes not merely the apparent results but the causes at work, 
 and the conditions of their action ; and it is on this that the 
 validity of his comparison depends, in so far as it relates to 
 similarity of mode of formation. But when we compare the 
 development of an animal from an embryo cell with the pro- 
 gress of animals in time, though we have a curious analogy as 
 to the steps of the process, the conditions and agents at work 
 are known to be altogether dissimilar, and therefore we have 
 no evidence whatever as to identity of cause, and our reasoning 
 becomes at once the most transparent of fallacies. Farther, 
 we have no right here to overlook the fact that the conditions 
 of the embryo are determined by those of a previous adult, 
 and that no sooner does this hereditary potentiality produce a 
 new adult animal than the terrible external agencies of the 
 physical world, in presence of which all life exists, begin to 
 
REVIEW OF THE HISTORY OF LIFE. 265 
 
 tell on the organism, and after a struggle of longer or shorter 
 duration it succumbs to death, and its substance returns into 
 inorganic nature, a law from which even the longer life of the 
 species does not seem to exempt it. All this is so plain and 
 manifest that it is extraordinary that evolutionists will con- 
 tinue to use such partial and imperfect arguments. Another 
 example may be taken from that application of the doctrine 
 of natural selection to explain the introduction of species in 
 geological time which is so elaborately discussed by Sir C. 
 Lyell in the last edition of his Principles of Geology. The 
 great geologist evidently leans strongly to the theory, and 
 claims for it the "highest degree of probability," yet he per- 
 ceives that there is a serious gap in it ; since no modern fact 
 has ever proved the origin of a new species by modification. 
 Such a gap, if it existed in those grand analogies by which 
 we explain geological formations through modern causes, would 
 be admitted to be fatal. 
 
 A third illustration of the partial character of these hypo- 
 theses may be taken from the use made of the theory deduced 
 from modern physical discoveries, that life must be merely a 
 product of the continuous operation of physical laws. The 
 assumption, for it is nothing more, that the phenomena of life 
 are produced merely by some arrangement of physical forces, 
 even if it be admitted to be true, gives only a partial explana- 
 tion of the possible origin of life. It does not account for the 
 fact that life as a force or combination of forces is set in 
 antagonism to all other forces. It does not account for the 
 marvellous connection of life with organisation. It does not 
 account for the determination and arrangement of forces im- 
 plied in life. A very simple illustration may make this plain. 
 If the problem to be solved were the origin of the mariner's 
 compass, one might assert that it is wholly a physical arrange- 
 ment both as to matter and force. Another might assert that 
 it involves mindjand intelligence in addition. In some sense 
 both would be right. The properties of magnetic force and of 
 
266 THE CHAIN OF LIFE. 
 
 iron or steel are purely physical, and it might even be within 
 the bounds of possibility that somewhere in the universe a 
 mass of natural loadstone may have been so balanced as to 
 swing in harmony with the earth's magnetism. Yet we should 
 surely be regarded as very credulous if we could be induced to 
 believe that the mariner's compass has originated in that way. 
 This argument applies with a thousandfold greater force to 
 the origin of life, which involves even in its simplest forms so 
 many more adjustments of force and so much more complex 
 machinery. 
 
 Fourthly, these hypotheses are partial, inasmuch as they fail 
 to account for the vastly varied and correlated interdepen- 
 dences of natural things and forces, and for the unity of plan 
 which pervades the whole. These can be explained only by 
 taking into the account another element from without. Even 
 when it professes to admit the existence of a God, the evolu- 
 tionist reasoning of our day limits itself practically to the 
 physical or visible universe, and leaves entirely out of sight the 
 power of the unseen and spiritual, as if this were something 
 with which science has nothing to do, but which belongs only 
 to imagination or sentiment. So much has this been the case 
 that when recently a few physicists and naturalists have turned 
 to this aspect of the subject, they have seemed to be teaching 
 new and startling truths, though only reviving some of the 
 oldest and most permanent ideas of our race. From the 
 dawn of human thought it has been the conclusion alike of 
 philosophers, theologians, and the common sense of mankind, 
 that the seen can be explained only by reference to the unseen, 
 and that any merely physical theory of the world is necessarily 
 partial. This, too, is the position of our sacred Scriptures, and 
 is broadly stated in their opening verse ; and indeed it lies alike 
 at the basis of all true religion and all sound philosophy, for it 
 must necessarily be that " the things that are seen are temporal, 
 the things that are unseen, eternal." With reference to the 
 primal aggregation of energy in the visible universe, with 
 
REVIEW OF THE HISTORY OF LIFE. 267 
 
 reference to the introduction of life, with reference to the soul 
 of man, with reference to the heavenly gifts of genius and 
 prophecy, with reference to the introduction of the Saviour 
 Himself into the world, and with reference to the spiritual gifts 
 and graces of God's people, all these spring not from sporadic 
 acts of intervention, but from the continuous action of God 
 and the unseen world ; and this, we must never forget, is the true 
 ideal of creation in Scripture and in sound theology. Only in 
 such exceptional and little influential philosophies as that of 
 Democritus, and in the speculations of a few men carried off 
 their balance by the brilliant physical discoveries of our age, 
 has this necessarily 'partial and imperfect view been adopted. 
 Never indeed was its imperfection more clear than in the light 
 of modern science. 
 
 Geology, by tracing back all present things to their origin, 
 was the first science to establish on a basis of observed facts 
 the necessity of a beginning and end of the world. But even 
 physical science now teaches us that the visible universe is a 
 vast machine for the dissipation of energy ; that the processes 
 going on in it must have had a beginning in time, and that all 
 things tend to a final and helpless equilibrium. This necessity 
 implies an unseen power, an invisible universe, in which the 
 visible universe must have originated, and to which its energy 
 is ever returning. The hiatus between the seen and the unseen 
 may be bridged over by the conceptions of atomic vortices of 
 force, and by the universal and continuous ether ; but whether 
 or not, it has become clear that the conception of the unseen 
 as existing has become necessary to our belief in the possible 
 existence of the physical universe itself, even without taking 
 life into the account. 
 
 It is in the domain of life, however, that this necessity be- 
 comes most apparent ; and it is in the plant that we first 
 clearly perceive a visible testimony to that unseen which is the 
 counterpart of the seen. Life in the plant opposes the outward 
 rush of force in our system, arrests a part of it on its way, fixes 
 
268 THE CHAIN OF LIFE. 
 
 it as potential energy, and thus, forming a mere eddy, so to 
 speak, in the process of dissipation of energy, it accumulates 
 that on which animal life and man himself may subsist, and 
 assert for a time supremacy over the seen and temporal on 
 behalf of the unseen and eternal. I say, for a time, because 
 life is, in the visible universe, as at present constituted, but a 
 temporary exception, introduced from that unseen world where 
 it is no longer the exception but the eternal rule. In a still 
 higher sense, then, than that in which matter and force testify 
 to a Creator, organisation and life, whether in the plant, the 
 animal, or man, bear the same testimony, and exist as outposts 
 put forth in the succession of ages from that higher heaven that 
 surrounds the visible universe. In them, as in dead matter, 
 Almighty power is no doubt conditioned by law, yet they bear 
 more distinctly upon them the impress of their Maker, and 
 while all explanations of the physical universe which refuse 
 to recognise its spiritual and unseen origin must necessarily 
 be partial and in the end incomprehensible, this destiny falls 
 more quickly and surely on the attempt to account for life and 
 its succession on merely materialistic principles. 
 
 Here, however, we must remember that creation, as main- 
 tained against such materialistic evolution, whether by theology, 
 philosophy, or Holy Scripture, is necessarily a continuous, 
 nay, an eternal influence, not an intervention of disconnected 
 acts. It is the true continuity, which includes and binds 
 together all other continuity. 
 
 It is here that natural science meets with theology, not as an 
 antagonist, but as a friend and ally in its time of greatest need ; 
 and I must here record my belief that neither men of science 
 nor theologians have a right to separate what God in Holy 
 Scripture has joined together, or to build up a wall between 
 nature and religion, and write upon it "no thoroughfare." 
 The science that does this must be impotent to explain nature 
 and without hold on the higher sentiments of man. The 
 theology that does this must sink into mere superstition. 
 
REVIEW OF THE HISTORY OF LIFE. 269 
 
 In the light of all these considerations, whether bearing on 
 our knowledge or our ignorance, a higher and deeper question 
 presents itself, namely, that as to the relation of nature and o 
 man to a Personal Creator. To this it seems to me that the study 
 of the succession of life yields no uncertain reply. Call the pro- 
 gress of life an evolution if you will ; trace it back to primaeval 
 Protozoa, or to a congeries of atoms : still the truth remains that 
 nothing can be evolved out of these primitive materials except 
 what they originally contained. Now we find in the existence 
 of man, and in the tendency of the scheme of nature towards 
 his introduction, evidence that at least all that is involved in 
 the reasoning and moral nature of man must have existed 
 potentially before atoms began to shape themselves into crystals 
 or into organic forms. Nay, more than this is implied, for we 
 do not know that man and what he has hitherto been and 
 done constitute the ultimate perfection of nature, and we must 
 suspect that something much more than what we see in man 
 must be required for the origination of the chain of life. 
 What does this prove, in any sense in which human reason 
 can understand it ? Nothing less, it seems to me, than that 
 doctrine of the Almighty Divine Logos, or Creative Reason, as 
 the cause of all things, asserted in our sacred Scriptures, and 
 held in one form or another by all the greatest thinkers who 
 have attempted to deal with the question of origins. Falling 
 back on this great truth, whether presented to us in the simple 
 " God said " of Genesis, or in the more definite form of the 
 New Testament, " The Word was with God, and the Word was 
 God," we find ourselves in the presence of a Divine plan per- 
 vading all the ages of the earth's history and culminating in 
 man, who presents for the first time the image and likeness of 
 the Divine Maker; and this forms the true nexus of all the 
 separate chains of life. Had man never existed, such reason- 
 ing might have been speculative merely, but the existence of 
 man, taken in connection with the progress of the plan which 
 has terminated in his advent, proves the existence of God. 
 
270 THE CHAIN OF LIFE. 
 
 Divine revelation carries us a step farther, and teaches us to 
 recognise in Jesus of Nazareth God manifest in the flesh, the 
 Diving Logos dwelling among men. But though this is a doc- 
 trine of revelation and not of science, it. is in perfect harmony 
 with the plan of progress which we have been sketching. It is 
 the natural outcome of a process leading to the introduction 
 of a rational and accountable being, understanding some- 
 thing of the works and ways of God, that to him God should 
 reveal Himself, and that the Divine Logos, by whom were 
 " constituted the ages " x of the world's geological history, 
 should preside also over its future consummation, when all 
 the degradation that has sprung from the aberrations of fallen 
 and imperfect humanity shall be removed, and man himself 
 shall become fully a partaker of the Divine nature. 
 
 The world we live in is thus not necessarily a finished world, 
 and it is now marred by the sins of man. What it may be in 
 the future, we can perhaps as little guess as an intelligence 
 studying the Palaeozoic world could have understood that of 
 the present time. But it is a glorious truth to know that our 
 Maker has revealed Himself to us also as a Saviour, and that 
 as individuals we shall not perish, to be replaced by an im- 
 proved species in the future, but that we ourselves, as sons of 
 God, may enter into and possess the new earth and new 
 heavens of future aeons of the universe. Thus it would seem 
 that the Gospel of Jesus Christ is that which was wanting 
 to complete and j ustify the history of nature by bringing to 
 light the final " restitution of all things," and our own union to 
 God in a happy immortality. 
 
 1 The true meaning of Hebrews i. 2 and xi. 3. 
 
INDEX. 
 
 (Principally to Forms of Life noticed or illustrated?) 
 
 AGNOSTUS, 79 
 
 Buthotrephis, 92 
 
 Dinosaurs, 174 
 
 Alethopteris, 105 
 
 Butterflies, 150 
 
 Dipnoi, 123 
 
 Ammonites, 76 
 
 
 Discina, 66 
 
 Amphibians, 152 
 
 CALAMITES, 99, 105 
 
 Dragon-fly, 148 
 
 Amphipeltis, 85 
 
 Calymene, 80, 82 
 
 Dromatherium, 209 
 
 Ancyloceras, 77 
 
 Campsognathus, 179 
 
 Dryopithecus, 229 
 
 Antholithes, 101 
 
 Carcharodon, 132 
 
 
 Anthozoa, 57 
 
 Cardiocarpum, IOI 
 
 ECHINODERMS, 6 1 
 
 Angiosperms, 187 
 Anthropalaemon, 85 
 Antiquity of Man , 247 
 Apes, 228 
 
 Cephalaspis, 122 
 Cephalopods, 71 
 Ceratites, 75 
 Ceratodus, 126 
 
 Elasmotherium, 242 
 Elephants, 224 
 Eocene age, 213 
 EoDteris Qi 
 
 Arachnida, 150 
 Archseocyathus, 38 
 
 Ceteosaurus, 178 
 Cinnamomum, 198 
 
 -L-VJ|Jl.t.XlO, *y^ 
 
 Eoscorpius, 151 
 Eozoon 27 
 
 Archreopteryx, 172 
 Archegosatiras, 153 
 Archimulacris, 146 
 
 Clidastes, 169 
 Cockroaches, 146 
 Conocephalites, 79 
 
 Equine feet, 218 
 Equisetaceae 97, 
 Extracrinus, 64 
 
 Arctocyon, 228 
 
 Conodonts, 118 
 
 
 Asterophyllites, 103 
 Astylospongia, 51 
 Athyris, 67 
 
 Corah, 55 
 Cordaites, no 
 Coryphodon, 215 
 Crinoids, 6 1 
 
 FAVOSITES, 59 
 Ferns of Paleozoic, 1 06 
 Ferns, Tree, 97 
 
 BACULITES, 77 
 Baphetes, 155 
 
 Crioceras, 77 
 Crustacea, 79 
 
 Fishes, 120 
 Floras, distribution of, 
 
 Bathygnathus, 174 
 Batrachians, 152 
 Bats, 226 
 Beetles, 145 
 
 Cuttle-fishes, 71 
 Cyathaspis, 121 
 Cyathophyllum, 60 
 Cystideans, 62 
 
 20 1 
 Footprints, 152 
 Foraminifera, 32 
 Fruits of Devonian, IOI 
 
 Beginning of Life, 23 
 Belemnites, 78 
 
 Cythere, 83 
 
 Ganoids, 120 
 
 Beryx ? 133 
 
 DADOXYLON, 100 
 
 Gastropods, 70 
 
 Beyrichia, 83 
 
 Dapedius, 132 
 
 Glacial age, 233 
 
 Birds, 172 
 
 Davallia, 192 
 
 Glyptocrinus, 63 
 
 Bivalve shells, 69 
 
 Dictyonema, 53 
 
 Glyptodendron, 94 
 
 Blattina, 146 
 
 Dikellocephalus, 79 
 
 Gomphoceras, 73 
 
 Brachiopods, 63 
 
 Dinichthys, 127 
 
 Graptolites, 53 
 
 Brontotherium, 217 
 
 Dinoceras, 216 
 
 
274 
 
 INDEX. 
 
 HALISITES, 59 
 
 Moths, 148 
 
 Pterodactyls, 171 
 
 Heliophyllum, 59 
 
 Murchisonia, 70 
 
 Pteropods, 70 
 
 Heterocrinus, 63 
 
 Myrica, 194 
 
 Pterygotus, 84 
 
 Horse, 218 
 
 
 Ptilodictya, 55 
 
 Huronian age, 24 
 
 NAUTILUS, 71 
 
 Ptyonius, 154 
 
 Hydrozoa, 54 
 
 Neuropteris, 105 
 
 
 Hylonomus, 157 
 
 
 QUADRUMANA, 228 
 
 
 OLDHAMIA, 52 
 
 Quercus, 194 
 
 ICHTHYOSAURUS, 767 
 
 Onchus, 121 
 
 
 Implements, 245 
 
 Onoclea, 191 
 
 RECEPTACULITES, 38 
 
 Insects, 139 
 
 Oreodon, 221 
 
 Reptiles, 165 
 
 Isotelus, 82 
 
 Origin of Life, 23 
 
 Rhamphorhyncus, 171 
 
 
 Orthis, 66 
 
 Rhizopods, 34 
 
 Labyrinthodonts, 155 
 
 Orthoceras, 73 
 
 Ruschinites, 81 
 
 Lamellibranchiata, 69 
 
 Osteolepis, 124 
 
 
 Lampreys, 117 
 
 Ostracods, 83 
 
 SASSAFRAS, 190 
 
 Land-snails, 142 
 
 Otodus, 131 
 
 Scorpions, 151 
 
 Laurentian age, 24 
 
 
 Sea- lizards, 167 
 
 Lepidodendron, 108 
 
 PAL^ASTER, 62 
 
 Selachians, 130 
 
 Lepidosiren, 124 
 
 Palsechinus, 62 
 
 Sequoia, 197 
 
 Leptophleum, 98 
 
 Palaeoniscus, 129 
 
 Sharks, 120 
 
 Libellula, 148 
 
 Palseotherium, 212 
 
 Sigillaria, 109 
 
 Lingula, 65 
 
 Paradoxides, 79 
 
 Sphenophyllum, 92, 
 
 Liriodendron, 191 
 
 Pentacrinus, 64 
 
 103 
 
 Lituites, 73 
 
 Phaceps, 83 
 
 Sphinx-moth, 149 
 
 Loligo, 72 
 
 Phascolotherium, 210 
 
 Spirifer, 67 
 
 
 Pinnularia, 101 
 
 Sponges, 48 
 
 MACHAIRODUS, 227 
 
 Plagiaulax, 210 
 
 Squids, 72 
 
 Mammals, 207 
 
 Plants, earliest, 89 
 
 Stelliosaurus, 158 
 
 Mammoth, 240 
 
 Pleistocene, 240 
 
 Stenopora, 57 
 
 Man, advent of, 233 
 
 Plesiosaurus, 167 
 
 Stromatopora, 36 
 
 Mantids, 146 
 
 Pleurocystites, 63 
 
 Syringoxylon, 102 
 
 Mares-tails, 97 
 
 Pleurotomaria, 70 
 
 
 Marsiipials, 207 
 
 Pliosaurus, 168 
 
 TABULATA, 59 
 
 Mastodon, 224 
 
 Polyzoa, 59 
 
 Teliosts, 120 
 
 May-flies, 146 
 
 Post-glacial, 236 
 
 Terebratula, 66 
 
 Megalosaurus, I 
 
 Prodryas, 150 
 
 Trichospongia, 51 
 
 Megaphyton, 107 
 
 Productus, 68 
 
 Trigonocarpum, 101 
 
 Megatherium, 222 
 
 Protannularia, 91 
 
 Trilobites, 78 
 
 Microlestes, 208 
 
 Protosalvinia, 101 
 
 Turrilites, 77 
 
 Microsauria, 156 
 
 Proterosaurus, 166 
 
 
 Mil'epedes, 145 
 
 Protostigma, 92 
 
 XYLOBIUS, 145 
 
 Modern forests, 186 
 
 Protozoa, 27 
 
 
 Monotremes, 208 
 
 Psilophyton, 95 
 
 ZAPHRENTIS, 60 
 
 Mososaurus, 169 
 
 Pterichthys, 123 
 
 Zonites, 143 
 
 RICHARD CLAY AND SONS, LONDON AND BUNGAY. 
 
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