344 Case and Williston — Description of Reptilian Skulls. 



and a decrease in the size of the incisors from within outward. 

 The character of the incisors is evidently hypothetical as they 

 are shaded, but the arrangement is wrong as can be made 

 out from this specimen and from several others in the Ameri- 

 can Museum. There is no diastema and in no specimen of 

 Diadeetes is there any indication of an enlarged maxillary. It 

 was upon such an error that Cope founded the genus Empedias. 

 In figure 12, the palate, the arrangement of the bones is 

 wrong. The premaxillaries are never so wide, antero-poste- 

 riorly, as figured ; the prevomers extend much farther forward 

 than figured ; the palatine process of the maxillary is figured 

 as a palatine ; the pterygoids are figured as short bones with 



Fig. 2. 



Fig. 2. Lower jaw of Dia dectes lent us Marsh, x^. Mus. University 



of Chicago. 



the prevomers extending back as far as the posterior end of 

 the maxillaries ; an ectopterygoid is figured, — as already stated 

 we find no evidence of such a bone in the Diadectidw. We 

 have studied the known skulls of Diadeetes carefully for several 

 years and have found no evidence to warrant drawing the 

 sutures of the temporal region so definitely as Broom has done, 

 though they may be correct. 



The lower jaw. — The resemblance to the lower jaw of the 

 specimens of Diadeetes from Texas is very close, but the jaws 

 from New Mexico show the sutures and permit the outline of 

 the individual bones to be determined. On the inner side the 

 suture between the splenial and dentary is distinct in front 

 but is not traceable behind : its probable continuation is indi- 

 cated by the dots in the figure. Below the anterior Meckelian 

 opening the suture between the splenial and the surangular is 

 very distinct. The splenial takes the usual large part in the 

 symphysis. The suture between the angular and the bone 

 above it in the posterior portion of the jaw is distinct, but it is 

 somewhat uncertain what this bone is. The articular is not 

 marked off by distinct sutures, but on the surface of the bridge 

 between the anterior and posterior openings of the lower 



