398 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
heretofore known to occur in America. Should the Hystriz venustus of 
Leidy prove to really belong to the true Hystrivine, it brings this group 
for the first time into the North American fauna. 
The other species of extinct Porcupine was described by Professor 
Cope from teeth found in the Port Kennedy bone-cave, under the name 
of Erethizon cloacinum. 
ERETHIZON CLOACINUS Cope. 
Erethizon cloacinum Corr, Proc. Amer. Phil. Soc., xii, 1871, 93, fig. 19. 
This species is described from “a last superior molar of the left side 
and a portion of one of the inferior incisors”. The molar tooth is represented 
as differing from the corresponding tooth of Evrethizon dorsatus in two im- 
portant particulars: “One of these is the greater vertical depth of the 
“is nearly as deep as the internal, while 
external inflection of enamel”, which 
in L. dorsatum it is much shallower, the internal extending down to the 
alveolar border.” This, however, is a feature which I find to be very variable 
in £. dorsatus, sometimes presenting just the appearance claimed to charac- 
terize E. cloacinus. 'Vhe other character is the possession of two enamel 
islands, or annuli, in the posterior half of the triturating surface, while only 
one occurs in any of the large series of specimens of /. dorsatus now before 
me. “The size of the teeth in E. cloacinum,” says Professor Cope, “ are about 
equal to the largest seen in the £. dorsatum.” The specimens were found 
associated with the remains of different species of Megalonyx, Mylodon, 
Mastodon, Tapirus, Ursus, Meleagris, several species of extinct Coleoptera, etc., 
with which were mingled those of Lepus sylvaticus, a Squirrel closely allied 
to Sctwrus hudsonius, and several extinct species of Arvicola. 
