The Ancient Life History of the Earth | Page 4

Cycads. 142. Encrinus liliiformis. 143. Aspidura loricata. 144. Group of Triassic Bivalves. 145. Ceratites nodosus. 146. Tooth of Ceratodus serratus and C. Altus. 147. Ceratodus Fosteri. 148. Footprints of Cheirotherium. 149. Section of tooth of Labyrinthodont. 150. Skull of Mastodonsaurus. 151. Skull of Rhynchosaurus. 152. Belodon, Nothosaurus, Paloeosaurus, &c. 153. Placodus gigas. 154. Skulls of Dicynodon and Oudenodon. 155. Supposed footprint of Bird, from the Trias of Connecticut. 156. Lower jaw of Dromatherium sylvestre. 157. Molar tooth of Microlestes antiquus. 158. Myrmecobius fasciatus. 159. Generalised section of the Jurassic rocks. 160. Mantellia megalophylla. 161. Thecosmilia annularis. 162. Pentacrinus fasciculosus. 163. Hemicidaris crenularis. 164. Eryon arctiformis. 165. Group of Jurassic Brachiopods. 166. Ostrea Marshii. 167. Gryphoea incurva 168. Diceras arietina. 169. Nerinoea Goodhallii. 170. Ammonites Humphresianus. 171. Ammonites bifrons. 172. Beloteuthis subcostata. 173. Belemnite restored; diagram of Belemnite; Belemnites canaliculata. 174. Tetragonolepis. 175. Acrodus nobilis. 176. Ichthyosaurus communis. 177. Plesiosaurus dolichodeirus. 178. Pterodactylus crassirostris. 179. Ramphorhynchus Bucklandi, restored. 180. Skull of Megalosaurus. 181. Archoeopteryx macrura. 182. Archoeopteryx, restored. 183. Jaw of Amphitherium Prevostii. 184. Jaws of Oolitic Mammals. 185. Generalised section of the Cretaceous rocks. 186. Cretaceous Angiosperms. 187. Rotalia Boueana. 188. Siphonia ficus. 189. Ventriculites simplex. 190. Synhelia Sharpeana. 191. Galerites albogalerus. 192. Discoidea cylindrica. 193. Escharina Oceani. 194. Terebratella Astieriana. 195. Crania Ignabergensis. 196. Ostrea Couloni. 197. Spondylus spinosus. 198. Inoceramus sulcatus. 199. Hippurites Toucasiana. 200. Voluta elongata. 201. Nautilus Danicus. 202. Ancyloceras Matheronianus. 203. Turrilites catenatus 204. Forms of Cretaceous Ammonitidoe. 205. Belemnitella mucronata. 206. Tooth of Hybodus. 207. Fin-spine of Hybodus. 208. Beryx Lewesiensis and Osmeroides Mantelli. 209. Teeth of Iguanodon. 210. Skull of Mosasaurus Camperi. 211. Chelone Benstedi. 212. Jaws and vertebr? of Odontornithes. 213. Fruit of Nipadites. 214. Nummulina loevigata. 215. Turbinolia sulcata. 216. Cardita planicosta. 217. Typhis tubifer. 218. Cyproea elegans. 219. Cerithium hexagonum. 220. Limnoea pyramidalis. 221. Physa columnaris. 222. Cyclostoma Arnoudii. 223. Rhombus minimus. 224. Otodus obliquus. 225. Myliobatis Edwardsii. 226. Upper jaw of Alligator. 227. Skull of Odontopteryx toliapicus. 228. Zeuglodon cetoides. 229. Paloeotherium magnum, restored. 230. Feet of Equidoe. 231. Anoplothelium commune. 232. Skull of Dinoceras mirabilis. 233. Vespertilio Parisiensis. 234. Miocene Palms. 235. Platanus aceroides. 236. Cinnamomum polymorphum. 237. Textularia Meyeriana. 238. Scutella subrotunda. 239. Hyalea Orbignyana. 240. Tooth of Oxyrhina. 241. Tooth of Carcharodon. 242. Andrias Scheuchzeri. 243. Skull of Brontotherium ingens. 244, Hippopotamus Sivalensis. 245. Skull of Sivatherium. 246. Skull of Deinotherium. 247. Tooth of Elephas planfrons and of Mastodon Sivalensis. 248. Jaw of Pliopithecus. 249. Rhinoceros Etruscus and R. megarhinus. 250. Molar tooth of Mastodon Arvernensis. 251. Molar tooth of Etephas meridionalis. 252. Molar tooth of Elephas antiquus. 253. Skull and tooth of Machairodus cultridens. 254. Pecten Islandicus. 255. Diagram of high-level and low-level gravels. 256. Diagrammatic section of Cave. 257. Dinornis elephantopus. 258. Skull of Diprotodon. 259. Skull of Thylacoleo. 260. Skeleton of Megatherium. 261. Skeleton of Mylodon. 262. Glyptodon clavipes. 263. Skull of Rhinoceros tichorhinus. 264. Skeleton of Cervus megaceros. 265. Skull of Bos primigenius. 266. Skeleton of Mammoth. 267. Molar tooth of Mammoth. 268. Skull of Ursus speloeus. 269. Skull of Hyoena speloea. 270. Lower jaw of Trogontherium Cuvieri.


PART I.
PRINCIPLES OF PAL?ONTOLOGY.

INTRODUCTION.
THE LAWS OF GEOLOGICAL ACTION.
Under the general title of "Geology" are usually included at least two distinct branches of inquiry, allied to one another in the closest manner, and yet so distinct as to be largely capable of separate study. Geology,[1] in its strict sense, is the science which is concerned with the investigation of the materials which compose the earth, the methods in which those materials have been arranged, and the causes and modes of origin of these arrangements. In this limited aspect, Geology is nothing more than the Physical Geography of the past, just as Physical Geography is the Geology of to-day; and though it has to call in the aid of Physics, Astronomy, Mineralogy, Chemistry, and other allies more remote, it is in itself a perfectly distinct and individual study. One has, however, only to cross the threshold of Geology to discover that the field and scope of the science cannot be thus rigidly limited to purely physical problems. The study of the physical development of the earth throughout past ages brings us at once in contact with the forms of animal and vegetable life which peopled its surface in bygone epochs, and it is found impossible adequately to comprehend the former, unless we possess some knowledge of the latter. However great its physical advances may be, Geology remains imperfect till it is wedded with Pal?ontology,[2] a study which essentially belongs to the vast complex of the Biological Sciences, but at the same time has its strictly geological side. Dealing, as it does, wholly with the consideration of such living beings as do not belong exclusively to the present order of things, Pal?ontology is, in reality, a branch of