Fes., 1912. MAMMALS OF ILLINOIS AND WISCONSIN — Cory. 177 
Special characters — Under parts grayish brown, paler than the back 
but with no abrupt line of demarcation; length, 6 to 7 inches. The 
grayish brown under parts (not white or whitish), in connection 
with its size and length of tail, will distinguish it from others of our 
Mice. 
Description — General color brown, the dark brown shading gradually 
to lighter brown on the sides of the body and grayish brown on the 
belly; tail very scantily haired; molars or grinding teeth having tu- 
bercles on crowns forming three longitudinal rows. 
Measurements — Total length, 6.75 in. (171.4 mm.); tail vertebra, 
3.15 in. (80 mm.); hind foot, .75 in. (19 mm.). 
The House Mouse is an introduced species which has become 
distributed practically throughout North America in districts inhabited 
by man and occasionally away from settled localities. On account 
of its small size it does not do so much damage as its larger relative, the 
Rat, but its presence is considered equally undesirable, and its ability 
to get through very small holes often enables it to gain access to the 
drawer of a desk, where it immediately begins operations by reducing 
letters and papers contained therein to a mass of shreds to be used as a 
soft bed for a litter of young Mice. When present in any numbers the 
amount of food they consume is considerable, and their depredations 
in pantries and storerooms is too well known to require comment. 
They are unfortunately very prolific, several litters being born in a 
season. From 4 to 9 young are born in a litter, the usual number being 
5 or 6. The young ones reach the age of maturity when less than three 
months old. 
The ordinary vocal sounds produced by a House Mouse may be 
described as a shrill squeak, but several writers have given it credit 
for what they describe as a “‘song.’’ Mr. Seton says,* “Most persons 
are surprised to hear of singing Mice. The first I met was in my New 
York residence. Out of the black darkness of a cupboard at midnight 
came a prolonged squeaking, thrilling and churring, suggestive of a 
canary’s song but of thinner and weaker quality. There could be no 
question that it was a ‘singing mouse.’ Many cases are on record.’’ 
All efforts to exterminate the House Mouse in the United States have 
failed and, if anything, their numbers appear to be increasing. In 
this connection it is interesting to note that three hundred years ago 
the householder in England was annoyed by these little pests fully as 
much as are those of the present day; at least in 1607 Edward Topsell 
devoted several pages to describing various methods whereby they could 
be trapped or killed. He says:f 
* Life Histories of Northern Animals, I, 1909, p. 482. 
t Historie of Foure Footed Beastes, London, 1607, pp. 509-510. 
