1883.] The Extinct Rodentia of North America. 379 
rhiza to be very long, as in the Dasyproctidez ; nevertheless their 
transverse section and sculpture are much as in the genus Lagid- 
ium. The affinities of this form are, then, near to types now 
existing on the South American continent, but it presents charac- 
ters which show that it cannot be referred to any existing genus. 
The Amblyrhiza inundata may be described as frequently sup- 
porting itself on its hinder legs, with the entire hinder foot applied 
to the ground, and its smaller fore-legs hanging by its side. Its 
general bulk could not have been less than that of a doe Virgin- 
ian deer, What its habits could have been, cannot readily be in- 
ferred, but its food was doubtless of the general vegetable char- 
acter of other members of the order. The A. /atidens must have 
been larger than the male Virginian deer. 
Hyprocua:rus Briss. 
The only existing species of this genus, the Capybara, is the 
largest of Rodentia living, and is con- ee b 
fined to South America. Leidy has de- 
scribed a species from the Ashley river 
deposits near Charleston, South Caro- 
lina, under the name of H. @sopt. Its a 
teeth, the only portions known, are simi- {| 
lar to those of the Capybara, but accord- f} 
ing to Leidy, the inferior incisor tooth is fi} 
watt strongly ridged than in the living |i} a) 
Species, | 
Eriruizon F. Cuv. 
The existing American porcupine was ` 
represented in the Megalonyx beds by a 
Species, the Æ. cloacinum Cope, of which 
à Single tooth was found in the Port 
Kennedy bone cave. 
LAGOMORPHA, 
A rabbit-like animal, probably of the 
ecus Lagomys, was found in the Pott 
Ken : portions represent parts 0 
nedy bone cave, It is rather larger inferior molars found. 
rg the Lagomys brinceps of the Sierra : 
: da. It is of interest, because no species now inhabits the 
Part of the American continent. I have called it Lago 
