Cope.] -^U-; [March IS, 



Vertebrae with a zygospben articubition. Eigbt cervical vertebrre, the 

 anterior with a compressed hypapophysis, which soon becomes a keel, 

 which is absent on the eighth cervical and all following vertebrae. Four 

 anterior vertebrae without ribs ; seventh and eighth with long ribs. Di- 

 apophyses very short, except in the caudal region, where they are present 

 for half its length, increasing in length to the base where they are quite 

 elongate. Ciievron bones intercenlral. Neural spines of dorsal region 

 low, of caudal region rather elevated, oblique, and preceded bj^ a com- 

 pressed vertical prominence or anterior neural spine. The centra are 

 transversely segmented just in front of thediapophysis, except in the an- 

 terior part of the series. 



The angle of junction of the pubes is nearly right, and the pectineal 

 process is median, short and decurved. The ischia have a long common 

 suture, and are deflected downwards, meeting at less than a right angle. 

 Tuber a prominent angle. Tlie ilium presents a short subacute angle 

 representing the crista. There is a deep posterior notch of the acetab- 

 ulum. 



In Dipsosaurus dorsalis all the teeth on the maxillary bone are tricuspi- 

 date; these on the premaxillarj' are mostly simple, but one or two external 

 ones show a rudimental lateral cusp. 



Ckotaphytus Ilolbrook. 



The skeletons of the two most abundant species are before me, viz., the 

 G. coUarU Holbr. and C wislkerdi B. & G. The following description 

 includes both, and if any difterences between the two exist, they are 

 mentioned. 



The premaxillary has a long spine above and a concave border behind 

 on the palate, from which projects forwards a pair of juxtaposed processes 

 which together iorm a button-like process which has an anterior free 

 border. The nasals are wide and shortened by the removal of their 

 anterior border on account of the large size and partly vertical direction 

 of the nostrils. Frontal single, narrow ; pineal foramen touching coronal 

 suture, in the frontal bone in C. collnris, and in the parietal in G. loisli- 

 cenii. Prefrontal large, with a prominent preocular boss, not extending 

 posteriorly over the orbit. Lachrymal small in line with and touching 

 the jugal. Postfrontal wanting ; its place taken by a process of the 

 frontal. Postorbital large, uniting exteriorly with jugal and supra- 

 temporal. Parietoquadrate arch elevated ; supraoccipital bone loosely 

 articulated, not distinct from exoccipital. Quadrate with rather flat 

 conchs, the external the larger, and with straight external border. Post- 

 optics not reaching frontal, curved, with short posterior branch. Petrosal 

 with prominent subforaminal portion which has an open groove looking 

 downwards. Vomers short and wide, not separated by a groove. Pala- 

 tines flat, with short maxillary process. Pterygoids rather narrowed by 

 the large palatine foramina ; posterior part grooved and receiving basi- 



