156 



Tlie liyostcrnals and hyposlcrnals have nearly the same extent. Their 

 intervening suture crosses the sternum near the middle of the pedicles. 



Dr. Gra}-, who established the genus Dermatemys, represents the South 

 American species D. Mawii, with a pair of gular scutes. D. Berardii, of 

 Mexico, is represented by Dumeril as possessing a single symmetrical gular 

 scute, and this also is the case in two shells from Balize River, Yucatan, and 

 Tabasco, Mexico, described by Professor Cope as pertaining to another species 

 whicli he has named D. ahnormis. 



In Baptemys there is no trace of separation of gular scutes from the 

 humeral scutes as indicated in Fig. 6, Plate XV. The grooves defining the 

 latter from, the pectoral scutes occupy nearly the same position as in Derma- 

 temys, crossing nearly through the middle of the entosternal plate. 



In Emys the gular and humeral scutes fold deeply upon the upper surface 

 of the sternum, but in Baptemys, as is also the case in Dermatemys, the cor- 

 responding scutes fold only to the upper edge of the rounded border of the 

 sternum. 



The intervening grooves of the pectoral, abdominal, femoral, and caudal 

 scutes nearly equally subdivide the sternum of Baptemys. 



The pectoral and abdominal scutes extend upon the sternal jjedicles, and 

 are there separated from the marginal scutes by large intervening scutes, as 

 in the sea-turtles and in Dermatemys. In the same position in Dermatemys 

 ahnormis there are four of these scutes. In one of the specimens I have had 

 the opportunity of seeing there are four of these scutes on one side and three 

 on the other; but in this case it appears evident that the reduction is not the 

 usual condition in the species. 



There are three scutes on the sternal bridge of Baptemys which succes- 

 sively increase in size. The first or axillary scute joins the fourth and fifth 

 marginal scutes and the pectoral scute. The middle or submarginal scute 

 is hexagonal, widest transversely, and it joins the fifth and sixth marginal 

 scutes and the pectoral and abdominal scutes. The third or inguinal scute, 

 nearly twice the extent of that in advance, is also hexagonal. It extends 

 across the hyposternal upon the hyosternal plate, and joins the sixth and 

 seventh marginal scutes and the abdominal scute, an outward prolongation 

 of which to the inguinal notch separates it from the femoral scute. 



The axillary fossa reaches as far back as the posterior third of the fourth 



