26 A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



genus and species rest on the paratype; they are distinguished by the larger size 

 and the tuberculate condition of the bones of" the skull. There are no lines indicat- 

 ing the attachment of scutes as described by Cope. 



Genus DESMATODON Case. (Plate 8, fig. 2.) 

 Desmatodon hollandi Case, Annals Carnegie Museum, vol. IV, Nos. Ill and iv, 1908, p. 236. 



Type: A fragment of a maxillary bone with four teeth and the root of a fifth. 

 No. 1938 Carnegie Museum. From Pitcairn, Pennsylvania. 



Original description: "The teeth are of peculiar interest, as they represent 

 an intermediate stage between those of Bolbodon and those of Diadectes. They 

 seem to indicate with little doubt the existence of a new genus which may be called 

 Desmatodon hollandi. The teeth are transversely elongate; the crown is slightly 

 wider than the root and is also somewhat swollen in the anteroposterior direction. 

 The outer half of the crown rises gently into a sharp apex, from which there is a 

 sharp descent to the inner half, which is lower than the outer half. The inner side 

 of the apex is nearly vertical and presents a flat face inwards; this is more prominent 

 on the posterior and largest of the teeth than on the anterior ones. The surface 

 of the crown is marked with fine lines and the sides of the root show the same charac- 

 ter, but here the lines are coarser. The inner half of the crown of the anterior and 

 the posterior teeth shows no wear, but on the two in the middle there are surfaces 

 worn by attrition on both the inner half of the crown and on the apex. The relation 

 of this genus to its nearest related forms is indicated in the figure here given." (See 

 fig. 34.) 



Revised description: This genus is closely related to the genus Diadectes, but 

 the differences in size and character and also its geographical and geological separa- 

 tion from the Texas beds make it advisable to regard it as distinct. 



Genus DIADECTOIDES nov. 

 Diadectoides cretin sp. nov. 



Type: A vertebral column, nearly complete, with ilium, femur, tibia and fibula, 

 and fragments of the skull. No. 650 University of Chicago. From Willbarger 

 County, Texas. 



This skeleton resembles that of Diadectes in many respects and might at first 

 be considered as a young individual of that genus, but the proportions of the limbs, 

 the shape of the apices of the spines, and the free neural arch indicate a distinct 

 genus. The bones are covered with a hard matrix which permits the general form 

 to be made out, but conceals minor details. It was only after considerable study 

 that it was possible to be certain of the presence of hyposphene and hypantrum. 



Fig. 6 is after an original by Dr. Williston, who most kindly turned the specimen 

 over to me after having begun work upon it. 



The single sacral vertebra is the sixteenth of the series preserved; it is certain 

 that the number of presacrals is incomplete, probably four or five are wanting. 



The dorsal vertebra are, as in Diadectes, very similar throughout the series. The 

 spines are short and low, but instead of terminating in rugosities as in Diadectes, 

 they terminate in flat oval surfaces. The sides of the neural arch are swollen and 

 convex, as in Diadectes. The zygapophyses are horizontal; the neural arches are 

 wider than long, and the zygapophyses overlap so far as to bring the spines in con- 

 tact. The result is a short, heavy, vertebral column with very little possibility of 

 lateral motion. Hyposphene and hypantrum appear to have been present but are 

 obscured by the matrix at most places. The neural arches fit so closely upon each 



