280 HABITS AND INSTINCTS OF ANIMALS. CHAP. IX. 



but each colony prefers providing a domicile for itself. 

 These retreats are not, in general, more than from six 

 inches to a foot from the surface; but the pregnant 

 females will sometimes deepen the excavation to up- 

 wards of two feet by a very small alley or aperture, 

 which, after making several sinuosities, terminates in a 

 little chamber as big as a fist, furnished with a soft 

 bed of vegetables for the accommodation of the young. 

 The economic mouse, from the interesting history of its 

 manners given by Pallas, seems to have the social in- 

 stinct still more developed, since they seem to have 

 one common chamber for assembling in, near which 

 are others appropriated to receive the stores supplied 

 by their industry for winter food. We have already 

 spoken of the extraordinary migrations of this little 

 creature, which appears habitually to live in very large 

 societies. It has been said that the common domestic 

 mouse is not a social animal, because " each lives in- 

 sulated." The fact, however, is notoriously otherwise : 

 suffer them but to increase, and they will, as every 

 body knows, form little colonies, not, indeed, inhabit- 

 ing the same common dwelling, but with their burrows 

 close to each other, like houses in a street, and ap- 

 proached by one or more roads common to all the mem- 

 bers of the community. The bobac marmot has, 

 nevertheless, more sociability than our little domestic 

 pest: this species seems to live in societies of from 

 twenty to forty. By consulting the valuable pages of 

 Dr. Richardson's first volume *, it will be seen that the 

 greatest number of the American marmots, and similarly 

 shaped quadrupeds, are particularly and permanently 

 social ; even the American field mouse ( M us leucopus), 

 while laying up its hoards of provisions, seems to act 

 in concert ; " for the quantity laid up in a single night 

 is so great as nearly to equal the bulk of a mouse, and 

 renders it probable that several individuals unite their 

 efforts to form it." The burrows of the Arctomys 

 pruinosus, or whistler marmot, are close together ; for 



* Northern Zoology.. 



