482 The American Naturalist. [June, 
vals, from cellar to garret, as this tell-tale song gave notice of 
When removing it from the trap to the cage, and many- 
times afterward, it ran about a small room, and the most no- 
ticeable feature on these occasions was the unvaried song, it 
being especially loud if I caused the mouse to scamper around 
the room several times without stopping. When gnawing on 
the exposed wood in the cage, when eating, or when disturbed 
in its nest, this singing was also particularly loud ; in fact, 
upon any exertion, the song was produced, varying in volume 
in proportion to the amount of exercise. 
On Thanksgiving day, eleven days after her capture, my 
mouse had two young, poor, miserable, little creatures, but, 
nevertheless, able to squeak and make considerable noise. It 
was just previous to, and for some time after the birth of these 
young, that Miis sang most continuously. 
The young grew apace, and on December 14th, one was 
looking out of the nest, while the mother kept up a constant 
singing, probably being much excited thereby. At this stage 
the baby mice were funny little bodies, sparsely covered with 
hair and the dimensions of a respectable peanut. On the 19th, 
both of the young mice were out of the nest, and one was 
quite helpless, laying on his back kicking and panting after 
he had tumbled about the cage. I was afraid he would be un- 
able to get into the nest again, so I rendered some assistance. 
However, in about fifteen minutes he was out as before, tum- 
bling about in just the same rough manner, the mother all the 
while keeping up a constant singing, and alternately running m 
and out of the nest. After a time she picked up the little mouse 
by the side of the neck, carried it across the cage and put it in 
the nest, and I did not see it again. The other baby mouse 
was quite able to care for itself. 
On December 21st the mother mouse ate about half of one 
of her offspring, commencing at the head. The one devoured 
was the most backward of the two, and I found the lively fel- 
low, on this occasion, at the other end of the cage, the most 
distant point from his mother. I have had a full-grown Hes- 
