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XXXI. — On the Teeth of Species of the Genus Labyrinthodon (Mastodon- 

 saurus of Jaeger^, common to the German Keuper formation and the Lower 

 Sandstone of Warwick and Leamington. 



By RICHARD OWEN, Esq., F.G.S., F.R.S., &c. 



[Read January 1841.] 



Whether the light-coloured sandstone of Warwick be, as Dr. Buckland con- 

 ceives, the equivalent of the German Keuper, or, as Messrs. Murchison and Strick- 

 land contend, of the Bunter-sandstein, was a question which awaited the evidence 

 of organic remains for its decision. For, notwithstanding the nature and number 

 of the lithological characters collated by them, the latter authors do not insist upon 

 this as evidence decisive of the accuracy of their views, but are willing to set the 

 determination of the question upon the issue of organic remains, nay even of a 

 single Saurian. 



" If it could be shown," say Messrs. Murchison and Strickland, " that the fossils 

 which we have pointed out as characterizing the upper sandstone, occurred also in 

 the lower," — " and that the fragments of Saurians found in the sandstones of Guy's 

 Cliff and Warwick really belonged to the species peculiar to the Keuper, — then, 

 indeed, we should willingly allow that the lower sandstone also must be grouped 

 with that formation*." 



The fossil reptiles which chiefly characterize the German Keuper are of the genera 

 Dracosaurus and Mastodonsaurus ; the former belonging probably to the Saurian 

 order ; the latter being undoubtedly a huge Batrachian, hence originally called 

 ' Salamandro'ides ' by its discoverer Professor Jaeger. It is the evidence of the ex- 

 istence of remains of a species of the same peculiar extinct Batrachian genus in 

 the lower sandstones of Leamington and Warwick, that I now propose to lay before 

 the Society. 



The genus Phytosaurus, also called Cylindricodon and Cubicodon, is perhaps most 

 familiar, by name, to English geologistsf, as a Keuper fossil : it is, however, merely 

 a nominal genus, being founded on the socket of the tooth of some other reptile. 



* Geol. Trans., 2n(i Series, vol. v. p. 345. 



t From the circumstance of its supposed existence in the Wealden formation. 



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