6 Myron Harmon Swenk 
even dorsally (in E. e. epixanthum the wholly black hairs are 
much more numerous dorsally and the under parts have very few 
pale-tipped hairs except on extreme sides), while the dense, 
spinous bristles on the under side of the tail are largely or wholly 
brownish yellow (wholly jet black in E. e. epixanthum). . 
Compared, also, with the description of E. e. nigrescens, which 
is evidently a form very close to typical epixanthum, but blacker, 
the Nebraska animal is again slightly larger (the adult ¢ type of 
E. e. nigrescens is 740 mm. long; tail vertebrae, 210; hind foot, 
go) and differs in coloration much as from typical epixanthum, 
only in even greater degree, since in FE. e. nigrescens the long 
dorsal hairs are almost wholly black, with pale-tipped hairs only 
on the nape, sides of lower back and thighs, while the under parts 
are wholly sooty black and the long, spinous bristles on the sides 
of the tail are black, broadly tipped with yellowish white. 
From E. e. myops the Nebraska form differs, as does typical 
epixanthum, in the paler, less yellow coloration of the pale-tipped 
hairs of the sides, flanks and sides of the tail, and by the sides of 
the face and interorbital region being less grayish-haired in the 
mature animal. It also appears to be a larger animal than E. e. 
myops. EE. e. couesi is smaller than E. e. bruneri, but the two are 
apparently very similar in coloration. 
Compared with an adult 2 specimen of the Canada porcupine, 
E. dorsatum dorsatum (Linnaeus)’ from Wisconsin (Sayer, 
November 11, 1907, E. Heller; Field Mus. Nat. Hist., 16284), 
the Nebraska porcupine differs in the more abundant long, pale- 
tipped hairs, which are yellowish gray or greenish yellow in color 
(comparatively few and white or yellowish white for the terminal 
one-fourth or one-fifth of their length in FE. dorsatum), in the 
long, yellowish bristles on the sides of the tail (much shorter and 
white or whitish in E. dorsatum), in the more grayish legs 
(mostly black in E. dorsatum), in the largely brownish yellow 
color of the under side of the tail (wholly jet black in FE. dor- 
satum), and in the white or yellowish, dusky tipped quills of the 
lower back, rump and flanks (quills of the lower back and flanks 
clear white with the extreme tips black, of the rump wholly black, 
T Syst. Nat., ed. 10, I, p. 57 (1758). 
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