THE FAUNA OF MONTANA TERRITORY. 535 


















it inhabiting the hollow trees on the Yellowstone, and it may 
build these summer-houses in the branches to avoid the flood 
Which occurs at the breaking up of the ice in spring, the 
ater being dammed up in this part of the river so as to 
mise it several feet above its banks, and much higher than in 
the summer rise. From the east base of the Rocky Moun- 
ins, entirely across, I found signs of this animal, usually a 
of cactus or other thorny stems, protecting its holes 
ng the rocks, and further west, large piles of twigs for 
the same purpose. I saw no signs of it, however, in the Cœur 
eñe Range or òn the Columbia Plains, so that it seems 
ly separated, locally as well as physically, and in habits, 
its nearest relative the WV. occidentalis, or bushy-tailed 
Bat, west of the Cascade Range. `I did not succeed in trap- 
Pog, shooting, or poisoning a specimen. 
: Mouse ( Arvicola pauperrima, nov.sp.*? No.126). 
teat Plain of Columbia, near Snake river, Oct. 9, 1860. 
the many other species described by Baird and others. i 
m it common on the Great Columbian Plain, after getting 
Wite out of sight of trees, and where the ground is covered 
omly with a coat of short scattered grass. Its burrows 
mt the only ones observed there, and by looking a few 
Yards ahead, while my horse walked quietly along, I could 
Ae May of the little inhabitants sunning themselves during 
as even more abundant on the grassy rolling hills be- 
Snake and Walla Walla rivers, and all I saw seemed 
of about the same size as this specimen. Scarcely any 
mmal was to be seen where this lived, and water me 
to be found for distances of twenty miles, so that " 
092, nead, Linch; body, 3.87; tail, vert., 0.75; hairs, 1.00: fore-arm, 0.87; 
38. 
ìi ear, 0.25 x0 
