SYSTEMATIC DESCRIPTIVE GEOLOGY. 



been some at least that differ so entirely in their structure ft -mi any 

 which now exist as to make it impossible to arrange their fossil remains 

 with any known class of animals." The animal thus referred to, being 

 clearly intermediate between fishes and lizards, was named by Mr. 

 Konig, Ichthyosaurus; and its structure and constitution were more 

 precisely determined by Mr. Conybeare in 1821, when he had occasion 

 to compare with it another extinct animal of which he and Mr. de la 

 Beche had collected the remains. This animal, still more nearly ap- 

 proaching the lizard tribe, was by Mr. Conybeare called Plesiosaurus. 31 

 Of each of these two genera several species were afterwards found. 



Before this time, the differences of the races of animals and plants 

 belonging to the past and the present periods of the earth's history, had 

 become a leading subjeet of speculation among geological naturalists. 

 The science produced by this study of the natural history of former 

 states of the earth has been termed Paleontology ; and there is no 

 branch of human knowledge more fitted to stir men's wonder, or to 

 excite them to the widest physiological speculations. But in the 

 present part of our history this science requires our notice, only so far 

 as it aims at the restoration of the types of ancient animals, on clear 

 and undoubted principles of comparative anatomy. To show how- 

 extensive and how conclusive is the science when thus directed, we 

 need only refer to Cuvier's Ossemens Fossiles ; M a work of vast labor 

 and profound knowledge, which has opened wide the doors of this part 

 of geology. I do not here attempt even to mention the labors of the 

 many other eminent contributors to Paleontology ; as Brocchi, Des 

 Hayes, Sowerby, Goldfuss, Agassiz, who have employed themselves on 

 animals, and Schlottheim, Brongniart, Hutton, Lindley, on plants. 



[2nd Ed.] [Among the many valuable contributions to Palaeonto- 

 logy in more recent times, I may especially mention Mr. Owen's Reports 

 on British Fossil Reptiles, on British Fossil Mammalia, and on the 

 Extinct Animals of Australia, with descriptions of certain Fossils indi- 

 cative of large Marsupial Pachydermata : and M. Agassiz's Report on 

 ike Fossil Fishes of the Devonian System, his Synoptical Table of 

 British Fossil Fishes, and his Report on the Fishes of the London Clay. 

 All these are contained in the volumes produced by the British Asso- 

 ciation from 1839 to 1845. 



31 GeoL Trans, vol. v. 



82 The first edition appeared in 1812, consisting principally of the Memoirs 

 to which reference has already been made. 



