RODENTIA MURINAE MUS MUSCULUS. 



443 



List of specimens. 



MUS MUSCULUS, Linn. 



Common Mon.se. 



Mus Muxulus, LINN. Syst. Nat. I, 1766, 83. 



KEYS. & BLAS. Wirb. Europ. 1842, 37. 



WAGNER, Suppl. Schreb. Ill, 1843, 409. 



AUD. & BACH. N. Am. Quad. II, 1851, 277 ; pi. xc. 



BUEMEISTEB, Thiefc Bras. I, 1854, 155. 



GIEBEL, Saugt. 1855, 557. 



SP. CH. Tail a little longer than the body. Soles entirely naked. Above grayish brown, finely lined with darker, 

 passing insensibly into ashy plumbeous, with a dull reddish tinge on the belly. No distinct line of demarcation. Tail 

 dusky all round ; feet ashy brown. 



It is not necessary to enter into any lengthened description of the external form of the com 

 mon house mouse, as its characteristics are much as in the large rats already described. The 

 tail is usually a little longer than the hody. 



The color of the upper parts is usually of a grayish hrown, very finely and intimately lined with 

 blackish, sometimes with a tinge of rusty. This passes very insensibly through the rather 

 more yellowish sides into the ashy plumbeous of the belly, without any dividing line of any 

 kind. There is on the belly a faint wash of a light mud color. The feet are ashy brown ; the 

 under part of the tail scarcely lighter than the upper. 



While this is perhaps the most constant color, there are occasional variations. Thus, in a 

 series from Middleboro', (864,) the under parts are of quite a pure yellowish white ; the upper 

 parts are lighter than as described ; the sides are washed faintly with fulvous, and the outside 

 of the whitish belly exhibits a brownish tinge, forming a band. The feet are almost pure white ; 

 the under surface, however, of the tail scarcely lighter. This same condition is seen in speci 

 mens from Sweden. 



On the other hand, the body is sometimes much darker than usual. One specimen from 

 Burlington, Vermont, (1316,) is as dusky as in most skins of the black rat. 



It is not easy to confound the white-footed native mouse of our country with the house mouse 

 in any of its phases, as its much larger ears, hairy heels, sharply defined white belly and feet,, 

 and many other characters, will at once distinguish it. 



The house mouse is originally a native of Europe and Central Asia. At the present time ife 



