OKDEKS OF MAMMALIA. 



351 



their habits, bvit some are furnished with prehensile tails, and live 

 in trees. 4. Casioridcs or Beaver family, comprising the Beaver. 

 The Beaver (fig. 2.")5) has webbed feet and a scaly tail, and the fin- 

 is an article of considerable vahie. It inhabits both 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. Muridce, comprising the Mice, JRats, Hamster, Lem- 

 mings, &c. The Eats and Mice are too well known to require more 

 than merely to be mentioned. C. Dipodidce, comprising the Jerboas 

 of the Old World, and the' Jumping Mice of America. 7. Myo.vidce, 

 comprising the Dormice, which must not be confouTided witla the 

 true Mice on the one hand, or with the Shrew Mice on the other 

 hand. 8. fiviuridce, comprising the Squirrels, Flying Squirrels, and 

 Marmots. The Flying Squin-els 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 (Cynomys Ludovicianus) of 

 North America. 



Order XIV. Cheiroptera. 



This order is undoubtedly one of the most distinctly circum- 

 scribed orders in the whole class of the Mammalia, and comprises 

 only the Bats. In many respects, however, it might be well to 



Fig. 256.— Skeleton and outline of Bat (Phyllosioma hastatiim). di Thumb; d, Fore- 

 flnger; li. Middle fluger; so Shoulder-blade; ci Collar-bone; /Thigh-bone; 

 (Tibia; ci Toes. 



regard the order as merely a modified branch of the InsecHvora, just as 

 the Pinnigrada are regarded as a modified offshoot of the Carnivora. 



