240 THE UNIVERSITY SCIENCE BULLETIN. 



sculpture of the maxillary bones. The species is much smaller than E. mega- 

 cephalus, or even than T. insignis, and the extent of the ossification of the 

 vertebral elements is intermediate between the two species. The inferior 

 surfaces of the intercentra are smooth, and the diapophuses are compressed. 

 The occipital condyles are depressed, and not very well distinguished in- 

 feriorly. The humeri have expanded extremities, with enlarged epicondyles, 

 well-developed condyles, and no epitrochlear foramen. Width of occipital 

 condyles, m. .016; elevation of dorsal vertebrae, .024; width of intercentrum, 

 .011; length of intercentrum (below), .207; five maxillary teeth in .015." 



According to Case, the material upon which the description of 

 Cope was based was mingled with the remains of other animals. 

 Of Cope's material only the intercentra are known to-day, ac- 

 cording to Case. We can not be certain, therefore, that the spines 

 described by Cope did not belong to some other animal. Williston 

 (1911) described briefly Marsh's material, but made no anatomi- 

 cal studies. 



The present comparative studies are based upon two incom- 

 plete and poorly preserved skulls from New Mexico, one from the 

 Yale Museum (No. 826), and one from the collection of the Uni- 

 versity of Chicago; and ten skulls from Texas, in the museum of 

 the universities of Chicago and Kansas, and the published draw- 

 ings of Case and Broom for specimens in the American Museum. 

 Unfortunately, the skulls from New Mexico are in such poor con- 

 dition that no satisfactory measurements or determinations of 

 sutures could be made. The skulls are apparently shorter and 

 broader than those from Texas, but this can not be established. 

 There is one constant difference which is discernible, however, 

 which is, in the opinion of the author, of generic rank. This is in 

 the matter of the arrangement of teeth on the palatine, transverse 

 and vomer bones. 



In the skulls from New Mexico the two large teeth on each of 

 these elements are without exception transverse in arrangement, 

 while in the skulls from Texas they are without exception longi- 

 tudinal with respect to each other, where both are present, or 

 where fresh scars are present. Specifically, the condition in the 

 skulls from New Mexico is as follows: Two transverse bones, one 

 with two teeth arranged transversely, one with one tooth; three 

 palatine bones, two with two teeth arranged transversely, and 

 one with one tooth; four vomers, two with two teeth arranged 

 transversely, one with one tooth and a fresh scar, arranged trans- 

 versely, and the other with one tooth. In all the Texas skulls at 

 hand there is not a single exception to the rule that the two teeth 

 on each of these elements are longitudinal with respect to each 



