|i! ' I 



i J; I 



11 



llllMlgffi 



Mmiii 



398 



MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



hcretofcte known to occur in America. Should the Hysttix venustus of 

 Leidy prove to really belong to the true Hystrivinfe, 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 cloacinvm. 



ERETHIZON CLOACINUS Cope. 



Erelhiiou cloacinum Cope, Proo. Amor. 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 difl'ering from the corresponding tooth of Erethizon dorsatus in two im- 

 portant particulars: "One of these is the greater vertical depth of the 

 external inflection of enamel", which " is nearly as deep as the internal, while 

 in E. dorsatum it is much shallower, the internal extending down to (he 

 alveolar border." This, hovever, isa feature which I find to be very variable 

 in E. dorsatus, sometimes presenting just the appearance claimed to charac- 

 terize E. cloacinus. The 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 E. dorsatus now before 

 inc. "The size of the teeth in E. cloacinum," says Professor Cope, " are about 

 equal to the largest seen in the E. dorsatum." The specimens were found 

 associated with the remains of different species of Megalonyx, Mylodoii^ 

 Mastodon, Tapirus, Ursus, Meleagris, several species of extinct Coleoptcra, etc., 

 with which were mingled those of Lepus sylvaticus, a Squirrel closely allied 

 to Sciurtis hudsonius, and several extinct species of Arvicola. 



