338 VERTEBRATE ANIMALS, 
North America and Europe. The Musquash resembles the 
Beaver in many respects, and is also a native of Northern 
America; but the Coypu is South American. 5. Muride, 
comprising the Mice, Rats, Hamster (fig. 183), Lemmings, &c, 
The Rats and Mice are too well known to require more than 
merely to be mentioned. 6. Dzfodide, comprising the Jerboas 
of the Old World, and the Jumping Mice of America, 7. 
Myoxide, comprising the Dormice, which must not be con- 
founded with the true Mice on the one hand, or with the Shrew- 
mice on the other hand. 8. Sciurvid@,comprising the Squirrels, 
Flying Squirrels, and Marmots, The Flying Squirrels do not 
really fly, but, like the “ flying” Phalangers, they take long 
leaps from tree to tree by means of laterally-extended folds of 
skin. The Marmots, unlike the typical Squirrels, are ground- 
animals, and live in burrows. An excellent example is afforded 
by the Prairie-dog (Arctomys Ludovicianus) of North America. 
ORDER XI. CHEIROPTERA.— This order is undoubtedly one 
Fig. 184.—Skeleton of a Bat (Pzevopus). . (After Owen.) 
of the most natural and distinctly circumscribed orders in the 
whole class of the Mammatia, comprising only the Bats. In 
