FIELD BOOK OF MAMMALS 



warm covering, the Muskrat has no fear of cold weather and 

 does not hibernate, being active throughout the year. 



Muskrats, when undisturbed, may be seen moving about at 

 any hour, but the best times for observation are early in the 

 morning and, more especially, just before sunset. They are 

 expert swimmers and travel in the water in preference to run- 

 ning on the ground, although they may go overland to quite 

 a distance for some favorite article of food. Still or slow- 

 moving water is best suited to their mode of living, but I 

 have seen a Muskrat in a swift, white-water, mountain creek 

 in the autumn when, perhaps, it was seized with a wanderlust 

 and was seeking a new home site. 



Family Muridae. Old World Rats and Mice 



Form typically rat or mouse-like; molar teeth three on each 

 side, crown pattern tuberculate (in species introduced into 

 North America), tubercles arranged in three longitudinal 



Subfamily Murinae. Introduced Rats and 

 Mice 



Characters as given under the Muridae, no special 

 modifications. 



Genus Mus 

 Dentition: Incisors, {; Canines, §; Premolars, %; Molars, f = i6. 



House Mouse. — Mus musculus musculus Linnaeus 



Names. — House Mouse; Domestic Mouse; Common 

 Mouse. 



General Description. — A small Mouse with long tail, 

 sparsely haired; pelage dull in color, no great contrast between 

 upper and lower parts. 



Color. — Sexes colored alike; no very noticeable seasonal 

 variation. 



Upperparts mixed yellowish brown and black; feet brown- 

 ish; tail above, dusky, below slightly lighter; underparts 

 ashy gray. 



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