176 PHILOSOPHY OF ZOOLOGY. 



usually bring forth two young at a birth. They have pec- 

 toral mammae, and a pendulous penis. They are crepus- 

 cular feeders, and become torpid during the winter. They 

 are more closely related to the quadrumana than to any of 

 the other groups. 



A. Claws on all the fingers as well as the toes. 



The fingers are not elongated, as in the true bats ; and 

 the membrane which extends on each side, from the head 

 to the tail, and embraces the legs and arms, is incapable of 

 supporting continued flight. The tusks are notched. The 

 incisors in the upper jaw are two in number, notched and 

 widely separated. Those in the lower jaw are six, and so 

 regularly and deeply divided by the notches, as to become 

 pectinated. 



18. GALEOPITHECUS. This is the only genus, and the 

 Lemur volans of LIN., the only known species. 



B. Some of the fingers destitute of claws. 



This division includes the true Bats, which have the 

 bones of the fore-arm and fingers elongated, for the purpose 

 of giving a greater expanse to the membrane of flight. 

 The fingers, indeed, have here lost their power of seizing 

 objects, having become ribs for the support of the wing *. 

 The thumb is small and free, with a claw as a hook, by 

 which the body is suspended during repose in the roofs of 

 caverns. The pectoral muscles are strong, and the sternum 

 has a mesial ridge like that of birds, to give to them a great- 

 er extent of base. The hind legs are feeble ; and the toes, 

 which five in number, are of equal height, and armed with 

 claws. They have no caecum. 



* This form is exhibited in the Plecotus auntus, or Long-eared Bat, 

 Plato 1, Fig. 1. 



