I6 KANSAS UNIVERSITY QUARTERLY. 



upper Missouri region, Nebraska, Kansas and New Mexico. Prob- 

 ably nineteen-twentieths of all the known specimens, however, have 

 been obtained in western Kansas. The material now in the Univer- 

 sity Museum, all from Kansas, comprises several hundred specimens 

 of these animals, including, probably, the best ones known. It is 

 upon this material that the following preliminary studies are chiefly 

 based. 



The genus Clidastes, as first described by Cope, was based upon 

 two dorsal vertebrae of C. igiiajiavus, the type species, from New 

 Jersey. Shortly afterward, however, he gave a full and careful 

 generic description, as derived from an unusually good specimen of an 

 allied species, C. propython, from Alabama. Only a little later. Marsh 

 described a genus, which he called Edestosaurus, from Kansas, but 

 without giving any real, distinctive differences from Clidastes, following 

 the very reprehensible practice of naming supposed new forms in 

 the hopes that future distinctive characters might be found. The 

 genus Edestosaurus has been rejected by nearly all save the authors 

 of the American text-books in Geology. It seems hardly necessary 

 to point out the identity. The only distinctive character the author 

 gave for his genus was the insertion of the pterygoid teeth, and even 

 this character he modified later — "Palatine (sic) teeth more or less 

 pleurodont. " * 



This character, even were it real, is of very slight value; indeed it 

 cannot be used to distinguish the species even. 



Clidastes is, without doubt, one of the most highly specialized 

 genera in the group, and, what is very interesting, is one of the latest. 

 It occurs in Kansas in the uppermost part of the Niobrara beds, 

 in the horizon so markedly characterized by the toothed birds. Both 

 Platecarpus and Liodon occur, though in diminished numbers, almost 

 to the very lowest portion, but Clidastes has never been found except 

 towards the top. From measurements made the past season, the 

 thickness of the beds in which these saurians occur cannot be less than 

 six hundred feet. 



The following species have been found in Kansas : none of them 

 are known to occur elsewhere. 



MOSASAURIDAE. 



MoiMnauridae QjVi\\\\)^-ax(\ in Cuvier, Ossem. Foss., 2nded., p. 338, 1834. 

 Clidastidae Cope, Extinct Batr. Rept. and Aves of N. Amer., Trans. Amer. 



Phil. See. xiv, p. 59, J 870. 

 Udestosauridae Marsh, Amer. Journ Sci. xxi, p. 50, July 1S78. 



""Amer. Joura. Sci. iii, June 1872. 



