

534 THE FAUNA OF MONTANA TERRITORY. 
shy, sometimes sitting on the bank until the boat got within a 
hundred yards of them. Their burrows, made in the bank near 
the mean water level, were, when inhabited, concealed by a 
large pile of branches, which would have seemed an acciden- 
tal drift to a casual observer, but if closely examined, showed 
design in their arrangement, the cut ends all lying above 
„water in one direction, and the others seeming fixed below 
by sand or clay piled on them. 
Near the source of the Little Blackfoot river were many 
ponds formed by beaver-dams, and I have everywhere no- 
ticed that these are constructed in shallow water, probably 
to deepen it, none being required in larger streams with 
banks suitable for burrowing in. Beavers seem rarely to 
build houses in Washington Territory, as they do in colder 
climates. 
Praw Mouse (Hesperomys Sonoriensis). This widely 
spread Mouse is common at Fort Benton, and was also taken 
at St. Mary’s valley, Washington Territory, in 1853, by Dr. 
Suckley. Like H. Gambelii, and some others, it lives m 
holes burrowed in the open prairie, far from tree oF bush, 
while H. leucopus and Nuttallii never seem to leave the 
woods. Has not this difference in locality caused variations 
in color, etc., which have led to incorrect specific distinction? 
(See Tamias). 
Rocky Mountain Woop-Rat (Neotoma cinerea). 
the banks of the Missouri, above Fort Union, were frequently 
seen large nests built in the low forks of willows and pop- 
lars, some of them large enough to form a good load for 2 
handcart ; probably measuring four feet through, and in form 
more or less spherical. They were composed of twigs, about 
half an inch thick and a foot long, dry, and densëly inter- 
woven. The soldiers and others called them “ Eagle’s neste, 
but finding them without any cavity, and much like the m 
of Neotoma fuscipes of California in structure (except i a 
that species usually build on the ground), I decided that ete | 
were built by the species here mentioned. Dr. Hay den fo 

