281 



CLIDASTES. 



The extinct reptilian genus Clidastes, characterized by Professor Cope, 

 is especially distinguished from Mosasaurus and its nearer allies by the 

 possession of an additional mode of articulation to the ordinary one in 

 the vertebrae, such as is found in the living iguanas. The vertebrae are 

 otherwise nearly like those of Mosasaurus. The general form and construc- 

 tion of the skull and the character of the dentition are the same in both 

 genera. 



Half a dozen species of Clidastes have been indicated by Professors Cope 

 and Marsh, from remains found in the Cretaceous formations of New Jersey, 

 Alabama, and Kansas. 



Clidastes inteemedius. 



A species different from those described by the authors just named is 

 indicated by a small collection of remains, presented to the writer by Dr. J. 

 C. Nott, formerly of Mobile. The specimens, consisting of several jaw-frag- 

 ments and vertebrae, were taken from an excavation 40 feet beneath the 

 surface, imbedded in the rotten limestone, of Cretaceous age, in Pickens 

 County, Alabama. 



The remains indicate a species of more robust proportions than Clidastes 

 propython, described by Professor Cope, from the great part of a skeleton 

 discovered in the same formation near Uniontown, Alabama. It was a third 

 less in size than the typical species C. iguanavus, described by the same 

 author, from an isolated dorsal vertebra obtained from the Cretaceous green 

 sand of New Jersey. 



Fig. 1, Plate XXXIV, represents the anterior extremity of a dentary bone, 

 probably more than one-half of the whole. It would appear to have been 

 proportionately of greater depth and thickness in relation with its length than 

 in C. propython. It is also of more uniform depth at its fore part and less 

 pointed at the end. 



The fragment contains the remains of a series of nine teeth, occupying a 

 space of 5£ inches. The teeth surmount robust osseous pedestals, of which 

 about two-thirds of the length are included within about an equal extent of 

 the depth of the jaw. 



The crown of a second tooth, (Fig. 5,) inclosed within a cavity of the 

 pedestal of its predecessor, is 5 lines in length and about 2i lines in breadth 

 36 g 



