284 PALEONTOLOGY 



birge," near Bonn, show different .stages of transformation of 

 the Rami diluviana, ( rdf. Tertiary shales from Bombay have 

 made known to the author the small fossil Rana pusilla. 



Of the salamander family, the most noted fossil is that 

 which was referred, when first discovered at CEningen in 1726, 

 to the human species, as Homo diluvii testis. Cuvier demon- 

 strated its near affinities to the water-salamander (Menapoma) 

 of the United States : more recently a living species of sala- 

 mander has been discovered in Japan which equals in size the 

 fossil in question — Andrias Scheuchzeri. 



A retrospect of the foregoing outline of the palaeontology 

 of the class of reptiles shows that, unlike that of fishes, it is 

 now on the wane ; and that the period when Reptilia flourished 

 under the greatest diversity of forms, with the highest grade 

 of structure, and of the most colossal size, is the mezozoic. 

 The progress of air-breathing vertebrates, graduating by close 

 transitional steps from the water-breathing class, has been 

 checked, as if it had been unequal to the exigencies and life- 

 capacities of the present state of the planet. Reptiles have 

 been superseded by air-breathers of higher types, which cannot 

 be directly derived from the class of fishes. A more general- 

 ized vertebrate structure is illustrated, in the extinct reptiles, 

 by the affinities to ganoid fishes shown by the GanocepJwila, 

 Labyrinthodontia, and Ichthyopterygia ; by the affinities of the 

 Pterosauria to birds, and by the approximation of the Dino- 

 sauria to Mammals. It is manifested by the combination of 

 modern crocodilian, chelonian, and Lacertian characters in the 

 Gryptodontia and Dicynodontia ; and by the combined croco- 

 dilian and Lacertian characters in the Thecodontia and Saurop- 

 terygia. Even the Ghelonia of the Purbeck period illustrate 

 the same principle, by the more typical number of modified 

 hsemapophyses, or abdominal ribs, entering into the composition 

 of their plasl ron. 



