568 U. S. P. R, R. EXP, AND SURVEYS---ZOOLOGY---GENERAL REPORT. 
ERETHIZON, F. Cuvier. 
Brethizon, F. Cuvier, Mém. du Mus. TX, 1822, 426, 432. 
For the principal characters of the skull and teeth, I would refer to the diagnosis of the family 
Hystricidae and sub-family Cercolabinae. In distinction from Cercolabes, the tail is short, 
thick and depressed ; covered above at the base with hairs and spines, at the apex and on the 
under surface with stiff bristles. Nostrils closely approximated. Feet short and broad. Toes 
(4, 5,) all armed with long and curved claws. 
The genus Lrethizon is confined to North America, exhedting perhaps, into Mexico on the 
south, and ranging to the parallel of 67° on the north, and from the Atlantic to the Pacific. 
It is very closely allied to the South American and Mexican Cercolabes, but is readily distin- 
guished by the much shorter and stouter tail, which is well covered with hairs and spines, and 
is incapable of prehension. The nostrils are more approximated, being separated by an 
extremely narrow partition. The anterior molar is usually considerably larger than all the 
others. 
The hind feet differ in having a distinct inner toe, which is armed with a large claw; the 
feet lack the projecting semi-circular lobe on the inner side, seen in Cercolabes. The naked soles 
are covered with minute tubercles. The upper lip is slightly notched above the incisor teeth, 
but there is no dividing groove, or naked mesial line, as in the Old World porcupines ; even 
the narrow septum between the nostrils is not destitute of hairs. The body is stout, and 
covered on the upper parts with a long and dense fur, which hides the spines. The limbs are 
short and strong. 
The most important differences between Erethizon and Hystrix will be found detailed in the 
characters of the sub-families to which they respectively belong. 
ERETHIZON DORSATUS. 
White Haired Porcupine. 
Hystriz dorsata, Linn. Syst. Nat. (ed. 10) i, 1758, 57.—Is. (ed. 12) I, 1766, 76. 
ERX LEBEN, Syst. 1777, 345. 
Bopparrt, El. Anim. I, 1784, 128, (from Pennant.) 
Gme.in, Syst. Nat. I. 1788, 119. 
ScHREBER, Saugt. IV, 1792, 605; tab. clxix. 
Saw, Gen. Zool. Mamm. II, 1801, 13; pl. exxv. 
Kunt, Beitrage, 1820, 70. 
DesMarest, Mamm. IT, 1822, 345. 
Cozzens, Ann. N. Y. Lye. I, 1, 1823, 191, (habits.) 
Harian, F. Am. 1825, 190. 
Grirr. Cuy. IT, 127, 206, original fig.—In. V, 1827, 263. 
Fiscner, Synopsis, 1829, 368. 
Aun. & Bacu. N. Am. Quad. I, 1849, 278 ; pl. xxxvi. 
