162 
MAMMALIA. 
have never known him to make his home at any great distance 
from buildings. 
Rats are good swimmers, and in their migrations from place to 
place (which are usually performed at night, and thus escape 
notice) they do not hesitate to swim rivers and ponds that lie in the 
way. Though chiefly nocturnal, they are often seen in the day- 
time. 
They are excessively prolific, commonly bringing forth from 
seven to twelve young at a birth, and having several litters each 
season. Some idea of the number of Rats inhabiting large cities 
may be had from the fact that, at Paris, in a fortnight’s time, more 
than six hundred thousand were killed in the sewers. Their skins 
were manufactured into kid gloves. 
MUS MUSCULUS Linnaeus. 
House Mouse. 
The House Mouse is another exotic that has found the climate 
and productions of America so much to its liking that it has multi- 
plied and diffused itself over the whole of the inhabited portions of 
our continent. 
Like the rat, it abounds in our largest cities and makes itself a 
conspicuous, albeit unwelcome, member of the household; but unlike 
the latter it also inhabits districts as yet unoccupied by civilized man. 
Such places, however, do not seem congenial to its urban disposi- 
tion, and it is probable that none but those who, from long residence 
in the country, have acquired a taste for adventure, make bold to 
desert their traditional haunts, together with the cats and traps with 
which they have been for generations familiar, to seek new homes, 
amid new surroundings and new enemies. 
I have observed the House Mouse in many of the camps scattered 
through the Adirondacks, and have killed it, though rarely, at a 
considerable distance from the habitations of man. It is common 
