504 Life-histories of Northern Animals 



"On one occasion [he says*^] I captured a pair with 5 

 young, and placed them all in a cage well supplied with vari- 

 ous kinds of vegetables and grain. The next day several of 

 the young were killed and eaten, and in two or three days they 

 had all disappeared. Shortly afterwards the male, which had 

 been slightly injured, was found dead, and partly devoured by 

 his rapacious spouse. After this I fed my specimens with meat 

 as well as grain, which they ate, and, as long as they were 

 supplied with it, they lived together harmless; but no sooner 

 was this withheld, than the old ones, both male and female, 

 devoured their young. Though all are more or less carnivor- 

 ous, they are not generally so bloodthirsty as to devour each 

 other of their young when not supplied with flesh.'* 



Bailey says of those that he observed near Pembina:^" 

 "I think it eats the seed of pennycress {Thlaspi arvense), 

 which has become so thick that in some fields nothing else can 

 grow.'* Besides this he found these Mice cutting down grain 

 and grass for the seeds. 

 ECO- Thus it is shown to do a little mischief to the crops by 



VALUE cutting them down and about an equal amount of good by 

 destroying a troublesome weed. 



STOR- It has the storage habit well developed, as it does not 



hibernate, but, like others of its family, is active in all seasons 

 and weathers. Kennicott points out that it collects seeds, but 

 never roots. A mouse nest with a store of roots is likely to 

 be that of a Microtus but not of a Peromyscus. 



" Quad. 111., 1857, p. 94. 



1° Rep. Cm. U. S. Dep. Agr. (for 1887), 1888, p. 442. 



