INSTITUTE OF SCIENCE, PHILADELPHIA. 29 



Another marginal plate of much less breadth than the former is strongly- 

 concave above in a transverse direction and has the free border obtusely 

 rounded. The upper surface is marked by grooves above and below, as well 

 as along the middle, separating the upper scutal areas from those beneath 

 the plate ; but this condition may be anomalous in the specimen, and is not 

 obvious in others. The measurements of the plate are as follows : 



Width in a straight line transversely, . . . . . .120 mm. 



Breadth above fore and aft, . . . . . . . 160 " 



Greatest thickness, ......... 40 " 



Two other marginal plates, somewhat mutilated, have nearly the size 

 and form of the preceding, but have their free border acute, and resemble 

 the corresponding everted plates in the Red-leg Terrapin, Eviys rugosa. 

 They are crossed by grooves of the investing scutes, but do not exhibit 

 those running near the outer border in the former specimen. 



A fragment, the outer part of a marginal plate, which has been about 

 200 mm. in breadth fore and aft, is very thick and rounded, and resembles 

 in these respects the specimen of a marginal plate, referred to Etipachemys 

 r7igosus, from the phosphate beds of Ashley River, S. C, described in the 

 Journal of the Academy of Natural Sciences of Philadelphia, 1877, p. 232, 

 plate XXXIV., figs. 4, 5. It is uncertain whether it belongs to the same 

 individual, or even species, with the former specimens. 



Considerable portions of the anterior and posterior extremities of a 

 plastron, which in its entire extent was upwards of four feet in length. The 

 anterior portion, represented in figure 4, plate VI., consists of the greater 

 part of the left epiplastron with the contiguous part of the entoplastron and 

 the outer portion of the corresponding hyoplastron, and part of the right 

 epiplastron. The posterior portion consists of the posterior and outer parts 

 of both xiphiplastrons, with the adjacent outer parts of both hyoplastrons 

 adjoining the inguinal notches, as represented in figure 5, plate VI. 



The plastron beneath, coextensive with its fragments, is quite flat, rough 

 and porous, but nowhere sculptured. Its anterior extremity is moderately 

 projecting beyond the postero-lateral borders of the gular scute areas. The 

 posterior or caudal notch is broad and shallow. 



The groove defining the gular scute area behind crosses the epiplastron 

 in advance of the middle, at first curving inward from the free margin of the 

 plastron, and then abruptly backward and inward on the anterior extremity 

 of the entoplastron. The area of the pectoral scute is large, and the groove 

 defining it behind passes in a slightly oblique line from the axillary notch 

 backward and then turns directly inward. The groove defining the caudal 

 scute areas in front crosses the xiphiplastrons a short distance back of their 

 middle, making an abrupt bend at the outer third of its course. 



