PROCEEDINGS OF UNITED STATES NATIONAL MUSUEM. 443 



ward : lower lid about three times as broad as the upper. Jaws short 

 aiid tbick; sheaths short aud deep, that of the upper jaw euding under 

 the middle of the eye; a depression beneath the eye. The two tooth-like 

 l)rocesses at the symphysis of the lower jaw large and high, giving the 

 cutting margin a concave outline. 



Anterior extremities not greatly larger than the posterior, frequently 

 compressed in the anteroposterior direction, but sometimes nearly 

 terete. Five claws with stout nails. The whole anterior surface of the 

 leg covered with very large founded scales, approximately etpial in 

 size. Scales on the sole of the foot large. 



The posterior extremities are terete and clavate, and bear four flat- 

 tened, pointed nails. Scales on the heel large, two especially so. 



Color of the carapace yellowish-brown, the surface within the smaller 

 stria of each plate yellow. Sternum light dirty yellow. Head and legs 

 yellowish gray. Jaws yellowish. 



Specific distinctions. — The main differences which separate X. 

 Berlandieri from X. polyphemus and X. Agassizii relate to the size and 

 shape of the head and jaws, the size and shape of the legs, and to the 

 height of the shell. In A'. poVypliemus the length of the carapace is 

 more than twice the height of the shell, while in X. Berlandieri the 

 length of the former is considerably less than twice the height of the 

 latter. In tlie former species the fore legs are largest at the exti-eniity, 

 while in the latter they are largest at the knees. In A', polypliemus again 

 the cutting edge of the lower jaw is nearly straight, while in A. Ber- 

 landieri it is very considerably arched, giving the mouth a hmclc's hill 

 api^earance. Many other minor differences exist in the arrangement of 

 scales on the legs, and the like. 



Size. — Of the three species, A. Berlandieri is the smallest. The 

 adults of A. polyphemus and A'. Agassizii are of about equal size. The 

 following table gives the actual measurements of greatest length and 

 breadth of six adult specimens : 



Allied genera. — The Brazilian Tortoise, Chelonoidis tahulata, in- 

 habiting the northern parts of the neotropical region, although resem- 

 bling, when half grown, the species of Xerohates, differs from them all 

 in characters of generic value, such as the absence of a nuchal plate, 



