xiii PHYLUM CHORDATA 493 



considerable range of modification within the order in adaptation 

 to different modes of life. The Colugos (Galeopithecus, Fig. 1134) 

 have a fold of skin (patagium) extending along each side of the neck 

 and body and continued between the hind-legs, 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 (Macroscelidce) 

 have slender limbs adapted to progressing by leaps on the surface 

 of the ground. 



The Chiroptera (Fig. 1135) are the only Mammals which are 

 capable of active flight. The fore-limbs have the segments greatly 

 elongated, especially the fore-arm and the four ulnar digits, and 

 these support a thin fold of the integument which stretches to the 

 hind-limbs and constitutes the wing. A fold (inter-femoral 



FIG. 1135. Bat (Synotus barbastellus). (After Vogt and Specht.) 



membrane) also extends between the hind-limbs> and may or may 

 not involve the tail. The pollex is much shorter than the other 

 digits, is 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 claw- 

 less. The position of the hind-limbs is peculiar, and the knee is 

 directed backwards instead of forwards as in other Mammals ; 

 the five digits of the foot are all provided with claws. So complete 

 is the adaptation of the limbs to the purpose of flight that Bats 

 are only able to shuffle along with great difficulty on the ground ; 

 though with the aid of their claws they are able to climb and to 

 suspend themselves from branches of trees by the hind-feet. In 

 the Megachiroptera the muzzle is nearly always elongated, and the 

 pinna of the ear simple, while in the Microchiroptera the muzzle 

 is short, the pinna usually complicated by the presence of an inner 

 lobe or tragus, and often produced into remarkable arborescent 

 appendages, and the nose also often provided with elaborate leaf- 

 like or arborescent lobes. The surface is usually covered with 



