Case and Williston — Description of Reptilian Skulls. 339 



Art. XXX. — A Description of the Skulls of Diadecles lentus 

 and Animasaurus carinatus ; by E. C. Case and S. W. 

 Williston. 



The two skulls here described have recently come to light. 

 The first was collected by Case in the Baldwin Bone Bed on 

 Poleo Creek in Rio Arriba County, New Mexico, and the 

 second was collected by Baldwin near Animas, Colorado 

 nearly thirty years ago, but has lain undescribed among the 

 abundant material of Yale University. The matrix of the 

 second skull, an indurated blue clay, is different from any 

 occurring in the JSTew Mexican localities, but the similarity of 

 the skull to that of Diadectes and the geographical proximity 

 indicate that it is a member of the same fauna. 



Diadectes lentus Marsh. (Figs. 1 and 2.) 



Nothodon lentus Marsh, this Journal, vol. xv, p. 410, 1878. 

 Nothodon lentus Case, Publication 145, Carnegie Institution, p. 30, 1911. 

 Nothodon lentus Williston, American Permian Vertebrates, Chicago, p. 16, 

 1911. 



The only portions of the skull of this animal known pre- 

 viously were the few teeth described by Marsh and the imper- 

 fect top of a skull described by Williston in the paper cited 

 above. The history of the discovery and description of the 

 original specimen has been given by Williston in the paper 

 cited above (pages 7 and 8) and need not be repeated. The 

 uncertainty as to the generic identity of Nothodon and Dia- 

 dectes has been removed by the discovery of this specimen 

 associated with typical diadectid vertebrse with hyposphene 

 and hypantrum in the- original Baldwin bone bed. 



The skull was found in a matrix of soft, blackish, friable 

 clay on the banks of Poleo Creek about a mile above its junc- 

 tion with the Puerco river in Rio Arriba County, New Mex- 

 ico. Closely associated with the skull were found the two 

 jaws described in this paper and they would have been 

 regarded as belonging to the same specimen if several other 

 jaws of the same size had not been found with them. 



The anterior portion of the skull, as far back as the post- 

 orbital region, was taken out in plaster and the relation of the 

 parts can not be questioned. The posterior portion was 

 broken in the ground and recovered as fragments. As 

 restored, the skull resembles very closely that of Diadectes in 

 form and proportions. 



The top of the skull is very rugose in the occipital and fron- 

 tal regions, but on the sides of the temporal and facial regions 

 the bones are marked by a sculpture of fine pits. The 



