102 
NEW AMERICAN QUADRUPEDS. 
membrane chiefly black, most of them slightly tipt 
with pale brown; feet dusky; around the eyes 
blackish ; ears with minute, adpressed, brown hairs 
externally, and brownish-white internally. 
This species differs from P. sabrinus in several 
very striking particulars ; although a smaller ani- 
mal, the arm of the wrist which supports the flying 
membrane, is lli lines in length, whilst that of the 
former is only 9 : thus the smallest animal has the 
largest flying membrane. 
The fur of P. sabrinus is much the longest. The 
fur on the belly of the latter is white, whilst that 
of oregonensis has an ochreous tinge. The hairs on 
the tail of P. sabrinus is only slightly tinged with 
lead color at the roots, whilst in oregonensis it ex- 
tends to half the length of the hairs. The greater 
length, and less breadth, however, of the ear of the 
latter, is a sufficient mark of distinction. 
From our little Pteromys volucella, the difference 
is so great that it is unnecessary to institute a par- 
ticular comparison. Besides being much larger 
than our little species, and not possessing the beau- 
tiful downy white on the belly, the two species 
may be instantly detected, in the volucella having 
its hairs white to the roots, which is not the case in 
the other species. 
Di?nensions. 
Length from point of nose to 
root of tail, 
Tail to point of fur, 
Height of ear, posteriorly, 
6 inches 8 lines. 
6 “ o “ 
0 “ 7 “ 
