COPE ON NEW EXTINCT VERTEBRATA. 393 



XeROBATES ORTHOPYGrlUS, Sj^. 710V. 



This large land-tortoise is represented by numerous remains in my 

 possession. One of these includes the greater part of the entire animal, 

 exhibiting, besides the shell, the limbs and a perfect skull, with man- 

 dible. The si)ecimens were obtained by an expedition which, explored 

 the fossiliferous Loup Fork beds of Kansas, in charge of E. S. Hill. 



The genus Testudo, as left by Gray in the " Catalogue of Shield 

 Eeptiles", embraces two genera. To one of these Agassiz gave in 1857 

 the name of Xerohates, with a diagnosis. In 1869, Gray characterized 

 the two forms quite exactly (see his "Supplement to the Catalogue", etc.), 

 but retained the name Testudo for Agassiz's Xerohates, and gave Agassiz's 

 Testudo another name {Peltastes). As Xerohates was first proposed, it is 

 here retained. 



This species has numerous peculiarities. The most striking is the 

 form of the posterior free border of the carapace. Instead of being 

 rounded, it is transverse, presenting a rounded lateral angle on each 

 side. The marginal bones of this transverse portion are vertical, ex- 

 tending below the line of the lateral free marginals, and their edges are 

 very little recurved, although acute. The free marginals in front of the 

 latero-posterior angles are not recurved, but are obtuse and somewhat 

 incurved, presenting an abrupt contrast to the median marginals; the 

 whole arrangement of the free border thus differing from anything which 

 I have heretofore observed in this genus. The sides of the carapace 

 swell outward, and the scutal sutures are well marked. 



The plastron is a little concave, and has thickened borders. These 

 have the peculiarity of rising witn a vertical external face to meet the 

 inner inguinal and axillary buttresses of the carapace. There is no 

 transverse buttress or septum in this part of the plastron, and but a 

 slight one on the carapace. The postabdomiual bones are not prominent, 

 but are simply emargiuate. On the other hand, the clavicular (epi- 

 sternal) bones are produced into aflat beak, which is not emarginate, but 

 truncate in front. It is thickenod backward, and encloses a deep fossa 

 with the succeeding portion of the plastron. The pectoral scuta are ex- 

 ceedingly narrow, and the humero-pectoral dermal suture turns forward 

 to the axilla. The general surface is without sculpture. 



There are numerous osseous bosses on the limbs, doubtless ossifica- 

 "tions of large marginal and other dermal scuta. They have usually a 

 low apex, central or eccentric. 



The maxillary alveolar border is rather finely serrate, and the two 

 inner alveolar ridges are rugose. The premaxillaries are not prominent, 

 and are separated by a slight notch. The cranium is of medium pro- 

 portions, and neither elongate nor widened. The jjrofile is plane, except 

 a slight descent to the nares. The zygomata were probably complete, 

 but slender. They are broken off in the specimen, but preserved loose. 

 There is a fossa at the base of each exoccipital, and a wide one on the 

 basioccipital. The palatal concavity is deep, and the edges of the 

 Bull. iv. No. 2 



