186 W. G. Knight— Jurassic Vertebrates from Wyoming. 



rounded depressions. 



Akt. XXY. — Some new Jurassic Vertebrates from Wyoming. 

 First Paper; by Wilbur C. Knight. 



For the last three years the University of Wyoming has had 

 parties in the field collecting vertebrate remains from the Juras- 

 sic rocks. Much of the material collected is new to science 

 and will be described as soon as it is possible to study it properly. 

 Among the lower forms are two new species of Ceratodus, a 

 genus not well represented in the American terranes. 



Ceratodus robustus, sp. nov. (Fig. 1.) 



l. The description of this species is 



based upon the greater portion of a sup- 

 posed right mandibular tooth, the 

 anterior margin and first horn having 

 been broken off. The known portion 

 of the tooth is quadrangular in form. 

 The anterior and posterior margins are 

 nearly straight and are at right angles to 

 each other. Posterior inner corner of 

 tooth rounded. Exterior margin divided 

 robustus, natural into four short, broad rounded horns, 

 separated by three broad, shallow, 

 Surface of the tooth very large, and not 

 cut by the angular depressions as in most of the Ceratodi. 

 The tooth is fastened to a piece of the dentary bone that 

 measures 33 mm long, 31 mm wide and 10 mm thick. The frag- 

 mentary tooth measures 29 mm long, 31 mm wide and 10 mm thick. So 

 far as known there are no closely allied forms. This species was 

 discovered by the writer in Albany county, and was associated 

 with the bones of a crocodile and a supposed new Dinosaur. 



Ceratodus america?ius, sp. nov. (Fig. 2.) 



All that is known of this species is a left 

 mandibular tooth.* It is triangular in shape. 

 The interior and posterior margins merge into 

 one, and form a well-rounded outline. Anterior 

 margin nearly straight. . The junction of the 

 anterior and interior margins truncated. The 

 exterior margin is divided into four angular 

 horns, separated by three angular depressions. 

 The first and largest horn is separated from the second by a right 

 angular depression. The greatest length of the tooth is 21 mm , 

 greatest width 17 mm . This species is probably closely related 

 to C. guntheri\ Marsh. It was found by the writer in Carbon 

 county, and was associated with the bones of a Megalosaur. 



University of Wyoming, Laramie, Nov. 30th, 1897. 



* I am not absolutely certain that this is a mandibular tooth. It is possible that 

 one horn has been broken off, in whidi case it would belong to the right palate, 

 •f This Journal, III, vol. xv, page 76. 



