HYSTEICID^]— FOSSIL SPECIES. 



397 



Table IV. — List of specimens of Ekethizon dorsatus var. epixantiius. 



' In the Museum of Comparative Zoology, Cambridge, Mass. 



EXTINCT NORTH AMERICAN PORCUPINES. 



Two forms of extinct North American Porcupines have thus far been 

 indicated, described in each case from detached teeth. Hence their relation- 

 ship to the existing species is very imperfectly known. 



Dr. Leidy has described* a species from two detached molar teeth, dis- 

 covered by Dr. Hayden in the Pliocene deposits of Dakota, which he refers 

 to Hystrix, under the name Hystrix venustus. Of these teeth, Dr. Leidy 

 says: ''They apparently indicate a species of Porcupine, but in structure are 

 unlike those of the recent American Porcupine, Erethizon dorsatus, and ex- 

 hibit a more evident relationship with those of the Crested Porcupine, Hystrix 

 cristata of Europe." As is well known, the genus Hystrix belongs to a very 

 different group from the Porcupines of the New World, and. has not been 



» Journ. Acad. Nat. Soi. Phil., 2d ser., v, 1869, 343 ; U. S. Geol. Survey of Wyoming for 1870 (1871), 364. 



