House-mouse 



481 



The general colour is "mouse colour," that is, grayish colour 

 brown above, shaded on the under parts into ashy, more or 

 less tinged with yellowish. 



When compared with other Mice found in Manitoba, its 

 gray colour above and below without a sharp edge to it any- 

 where, and the absence of pure white combined with its large 



ears and its long, tapering 

 naked tail, will be found 

 sufficiently distinctive. 



Life-history. 



This species ranges range, 

 over the whole of the 

 civilized world as a para- 

 site or commensal of man- 

 kind. Its first appearance 

 about Carberry, Man., 

 was in the fall of 1886, 

 when I got some speci- 

 mens out of a stack. 

 Its chosen environment is a hole in the wall of a well- 

 stocked pantry. 



It is not known whether the male parent takes any interest ^LATI^G 

 in the young, or, indeed, whether or not the species pairs. 



It breeds without ceasing the whole year round. The 

 period of gestation is probably 25 days. The young number 

 5 or 6; they are weaned at about 2 weeks, and produce very 

 soon, probably at the age of 2J months. So that in one year 

 a pair of Mice could easily become 1,000, even allowing 

 for considerable destruction by their enemies. 



Among the unexpected foes of this animal is the cuterebra 

 or warble-fly. 



At Winnipeg, August 25, 1902, I was shown a Common 

 Mouse infested with three of the large warbles or skin-grubs. 

 The miserable little creature was nearly dead from exhaus- 



Fig. 140 — Upper diagram, left upper molars of genus 



Peroniyscus. 



Lower diagram, left upper molars of genus AIus. 



(Greatly enlarged.) 



