1918 | Camp: Burrows of the Rodent Aplodontia 519 
Coues (1877, p. 591) reviews the literature on Aplodontia up to 
his time, making, however, no mention of Lord’s interesting notes on 
the genus (1866, 1, pp. 346-358). 
The most important recent contribution to the life-history of aplo- 
dontia is comprised in the notes and photographs of Anthony (1916). 
This came to hand after the present paper had been prepared. 
The writer has not had access to an article by Murphy (1876), of 
which he has heard. 
For full systematic treatment of the genus Aplodontia and for 
lists of names, both vernacular and scientific, see Taylor (1918). 
Hapirat 
Like the beaver and some of the ground squirrels, the aplodontia 
seems to be of social habits, congregating in more or less extensive 
colonies in localities where conditions favor its existence. If a real 
social bond exists it must be a primitive one. The scattered nature of 
most of the colonies proclaim this; and the probable absence of voice, 
which usually accompanies social habits, is suggestive. 
The factors necessary for the existence of all the nine subspecies 
of Aplodontia now recognized seem to be: An abundant supply of 
certain food plants chiefly of riparian growth; and a soil at least 
moderately deep and firm, and with adequate drainage, where the 
animals can burrow. Hillside seepage areas and the banks of streams 
provide the usual situations of colonies. Colonies occurring in wooded 
and brushy places at a distance from water are sometimes inhabited 
only in the wet season (Shelton, MS, 1916), but if the food supply 
continues, such burrows may be used the year. round. 
Burrows 
Wherever the aplodontia lives it digs extensive underground tun- 
nels that in a populous colony form a network of passages a few 
inches beneath the surface of the ground (see fig. 1). Each burrow 
system has many openings to the surface, but excavated dirt and 
rubbish is pushed out usually at only a few of these holes. The three 
subspecies living along the coast of California invariably choose for 
the colony a spot within a dense tangle of ferns, thimbleberry and 
other low plants in wet or at least damp soil. So well concealed 
beneath tangled shrubbery are the unplugged burrows that the pres- 
