322 PROCEEDINGS OF THE NATIONAL UUSEVM. vol.38. 



nun. The shell was high and strongly arched from side to side. 

 Along the back ran a very feeble median keel and on each side a 

 strong lateral keel. The lateral keels are not as acute on their sum- 

 mits as are those of Il.crassa, but are rounded. On the side toward 

 the midline the base of each lateral keel is bounded by the deep and 

 sharply impressed sulcus which limits laterally the vertebral scutes. 

 Just in front of the sulcus which descends between contiguous costal 

 scutes the keel rises abruptly from the costo-vertebral sulcus and then 

 rounds off into the general level of the costal bone. On the slope of 

 the keel toward the median line a well-defined groove begins at the 

 crossing of the descending sulcus and runs backward, gradually dis- 

 appearing before reaching the next descending sulcus. The second 

 neural is L'.j mm. long, 16 mm. wide, and 7 mm. thick; the fourth, 

 not present, had a length of about 23 mm.; the fifth is 18 mm. wide 

 and !) nun. thick near the anterior and its length was approximately 

 14 mm. The left fourth costal plate is 23 mm. wide where crossed 

 by the costo-vertebral sulcus; 27 mm. at the distal end. "Where it 



Figs. 20-23.— Hoplochelys bicarinata. x§- ! front end of fourth peripheral— a, groove 



FUR PROCESS OF BYPOPLASTRONJ 6, LATERAL CARINA WITH GROOVE W'.oVK IT: 21, HINDER 1 SDOl FOl BTH 



peripheral; 22, front end of eighth peripheral— a, tit for process of htpoplastron; 23, eighth, 



NINTH, TIN hi \\n ELEVENTH PERIPHERALS. 



joined the neural the thickness is 8 mm.; through the lateral keel, 

 8 mm.; through the distal end, 5 mm. The rib-heads were rather 

 slender. The nuchal bone and both of the first peripherals are miss- 

 ing. The third peripheral is 27 nun. long; the fourth, 21 mm.: the 

 fifth, '-'I nun.; the sixth, 21 nun. The seventh is wanting on both 

 sides. The eighth is 25 mm. long; the ninth, 24 mm. At its front 

 the third peripheral is 23 mm. high and \) mm. thick. The succeeding 

 three are equally thick. Fig. 20 represents the front end of the 

 I'ou it h and fig. '_' 1 t he hinder end. The latter articulated with the ante- 

 rior process of the hyoplastron. This process continued forward in 

 a deep groove along the inner face of the fourth peripheral and 

 entered a pit in the third. There is also a small pit in the third for 

 the rib of the I'u-st costal, and in the fourth a larger one for the rib 

 <.f the second costal. Doubtless there were pits in the succeeding 

 three peripherals for the corresponding ribs, hut the upper borders of 

 these peripherals are broken away. The hinder end of the Lower 

 border of the fourth, the whole lower border of the fifth, and the 

 anterior end of the lower border of the sixth peripherals formed a 



