DERMATEMYDID^:. 



265 



The xiphiplastra were evidently small bones, but there is no remnant of them preserved. 



The width of the shell of this specimen was about 130 mm. An estimate based on the 

 width of the two costal plates shows that the length was approximately 185 mm. The animal 

 was therefore somewhat broader relatively than either Staurotypus salvinii or S. triporcatus. 



So far as known, this species differs from H. sahens in having the bones of the plastron 

 less firmly sutured with the peripherals and in having the latter bones, at least those of the 

 bridge region, without close suture with the costals. The bridge is much narrower. 



Hoplochelys saliens sp. nov. 

 Telt-figs. 326, 327. 



The only specimen of this species at present known was found by Dr. J. L. Wortman 

 in 1896, at the head of the Escavada Canyon, Rio Arnba County, New Mexico, in Torrejon 

 deposits. It belongs to the American Museum of Natural History and bears the number 



FIGS. 326 AND 327. Hoplochelys saUens. Carapace and plastron of type. 



portions in interrupted lines. 



Restored 



326. Carapace. 



327. Plastron and part of carapace. 



12OO. The shell, the only portion preserved, is considerably crusht, but is nearly all present. 

 The only parts missing are portions of the seventh and eighth costals, the hindermost neurals, 

 and some portions of the plastron. Unfortunately for an understanding of the structure of 

 the shell much of it was covered by a very refractory matrix, which adhered so closely that it 

 had to be ground away to the bone. As a result, it is difficult to determine in many places 

 the position of the boundaries of the scutes and sometimes of the sutures. Most of the periph- 

 erals, however, have been beautifully weathered out and preserved. 



In form the carapace (fig. 326) was oval, rounded in front and behind, and apparently of 

 some considerable elevation. The total length was close to 325 mm.; the width, close to 200 

 mm. There was a median keel of moderate height. On each side of this, at a distance of 50 



