542 MANUAL OF ZOOLOGY sect. 



enclosing the tail ; the fore- and hind-feet are both webbed, 

 and the tail is prehensile. The hedgehog (Erinaceus) has 

 the surface beset with pointed spines. The moles (Talpa) 

 and their allies, which are active burrowers, have the limbs 

 very short and stout and provided with extremely strong 

 claws. The jumping shrews {Macrosceledidm) have slender 

 limbs adapted to progressing by leaps on the surface of the 

 ground. 



The Chiroptera (Fig. 327) are the only mammals which 

 are capable of active flight. The fore-limbs have the seg- 



Fig. 327. — Bat (Synotus barbastellus). ( After Vogt and Specht.) 



ments greatly elongated, especially the fore-arm and the 

 four ulnar digits, and these support a thin fold of the integu- 

 ment which stretches to the hind-limbs and constitutes the 

 wing. A fold also extends between the hind-limbs and may 

 or may not involve the tail. The pollex is much shorter 

 than the other digits, directed forwards, and terminates in a 

 well-developed curved claw ; in the Megachiroptera, but not 

 in the Microchiroptera, the second digit also has a claw; the 

 other digits are always clawless. The position of the hind- 

 limbs is peculiar, and the knee is directed backwards instead 



