172 



half. The length of the plastron is estimated 1o have been about 14 inches; 

 its breadth at the root of the posterior extremity is 5£ inches; and at the root 

 of the anterior extremity has been rather less. The sternal bridges measure 

 7 inches fore and aft, and their length to the outer edge of the carapace is 5 

 inches. 



Other measurements of the shell are as follows : 



Inches. 



Length of second vertebral scute area, estimated at 4J 



Breadth of second vertebral scute area 3£ 



Length of third vertebral scute area 4£ 



Breadth of tbird vertebral scute area 3£ 



Length of fourth vertebral scute area 3£ 



Breadth of fourth vertebral scute area 3£ 



Breadth of second costal scute area, internally 4| 



Breadth of second costal scute area, externally 4§ 



Breadth of third costal scute area, internally „ 3| 



Breadth of third costal scute area, externally 3j£ 



Height of sixth and seventh marginal scute areas 2£ 



Length of hyposternals internally 5 



Breadth of hyposternals internally 5% 



Breadth of hyosternals 5£ 



Breadth of plate intercalated between the hyosternals and hyposternals G 



Extent of the same plate at the base externally, fore and aft 4§ 



Breadth of groove between pectoral and abdominal areas where it joins the pro- 

 jecting angle of the third sterno-costal scute areas 1\ 



Breadth of plastron at anterior suture of xiphisternais 4£ 



Breadth of pectoral scutes to sterno-costal scutes 4 and 4£ ■ 



Length of abdominal scute internally 3 



Length of femoral scute internally 3f 



Axillary scute area, length at middle If 



Axillary scute area, breadth at middle : 2£ 



First submarginal scute area, length at middle ...... 2| 



First submarginal scute area, breadth at middle. .'.. 2£ 



Second submarginal scute area, length at middle 2 



Second submarginal scute area, breadth at middle 2| 



Inguinal scute area, length at middle 2| 



Inguinal scute area, breadth at middle 2J 



The sacral vertebrae, represented in Figs. 11, 12, Plate XIX, are of pro- 

 portionately greater length than in Baena. The first one is nearly as long as 

 it is broad ; and the second is half as long again as the former, and is equal 

 in this respect to its breadth. 



The anterior articulation of the first sacral centrum forms a decided cup- 



* 



like depression, and not merely a transverse concavity like that in the snap- 

 per. The second sacral centrum is prolonged to an unusual degree beyond 



