MAMMALS. 597 



great singer, and his account of its accomplishments is a delightful bit of 

 mouse biography. He has set the songs to music, and given them names. 

 He describes one performance in the following words : " She was gam- 

 bolling in the large compartment of her cage, in a mood indicating intense 

 animal enjoyment, having woke from a long sleep, and partaken from 

 some favorite food. She burst into a fulness of song, very rich in its 

 variety. While running and jumping she rolled off what I have called 

 her Grand Role ; then sitting, she went over it again, ringing out the 

 strangest diversity of changes by an almost whimsical transposition of the 

 bars ; then without for an instant stopping the music, she leaped into 

 the wheel, started it revolving at its highest speed, and went through the 

 Wheel Song in exquisite style, giving several repetitions of it. After this 

 she returned to the large compartment, took up again the Grand Role, and 

 put into it some variations of execution that astonished me. One measure, 

 I remember, was so soft and silvery, that I said to a lady who was listen- 

 ing, that a canary able to execute that would be worth a hundred dol- 

 lars. ... So the music went on, as I listened, watch in hand, until 

 actually nine minutes had elapsed." 



The elegant little dormice of the Old World seem to connect the 

 squirrels and the mice, being like the former in their habits, and more like 

 the latter in structure. They live in the trees, running and jumping with 

 as much grace and agility as our squirrels, or sitting up on their haunches, 

 eat their nuts in exactly the same way as do the others. But when winter 

 comes, the dormouse becomes torpid and so lethargic as to have given rise 

 to a proverbial expression, — ' sleeps like a dormouse.' 



Before speaking of the true beaver, a few words must be said of the 

 giant fossil beaver which once inhabited the forests of the New World. 

 In structure it combined the characters of the beaver and the chinchilla ; 

 in size it equalled a full-grown black bear. It was contemporaneous with 

 the mastodon ; but no one knows anything about its habits. But few 

 specimens are known, less than a dozen being enumerated in the last 

 paper on the subject. It ranged from South Carolina and New York to 

 Michigan and Texas. 



The beaver is by far the most important of all the rodents, and as such 

 demands more space than we have accorded to any other member of the 

 group. There is but a single species in the world, and this inhabits the 

 northern portions of both continents. Between the beaver of Europe and 

 that of America there are some slight differences ; but not enough to make 

 them distinct species. At the time of the settlement of North America 

 the beaver supply of Europe was at a low stage, and hence the opening up 

 of a new source of skins was very important. At that time the beaver 



