476 ZOOLOGY SECT. 



(the majority of the order) lead a terrestrial life, and are active 

 burrowers ; they are on the whole a very uniform group, and 

 exhibit few such remarkable modifications as are to be observed in 

 some of the other orders of Mammals. They are nearly all furry 

 animals with five-toed, plantigrade or semiplantigrade limbs. The 

 tail is usually elongated, and may be naked or covered with fur ; 

 but sometimes, as in the Rabbits and Hares, it is very short. A 

 few special modifications, however, have to be noted in certain 

 families of Rodents. The Flying Squirrels have on each side a 

 fold of skin, the patagium, which serves as a parachute. The 

 African Flying Squirrels (Anomalurus) are remarkable also on 

 account of the presence of a series of overlapping horny scales on 

 the lower surface of the basal part of the tail. The Jerboas (Dip-us) 

 and their allies are characterised by the great relative length of 

 the hind-limbs the mode of locomotion of these remarkable 

 Rodents being by a series of leaps not unlike the mode of progres- 

 sion of the Kangaroo and by the reduction of the number of the 

 toes to three in some of them. The Porcupines (Hystricidou) have 

 numerous elongated spines or " quills ' : among the hairs of the 

 dorsal surface, and some of them have prehensile tails. The Agutis 

 (Dasyproda) have hoof-like claws, and the Capibara (Hydroclicerus) 

 has webs between the digits. 



The Insectivora are, in general, small, furry, burrowing Mammals 

 with plantigrade limbs and an elongated muzzle. But there is a 

 considerable range of modification within the order in adaptation 

 to different modes of life. The Colugos (Gcdcopitliccus) (Fig. 1054) 

 have a fold of skin 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 (Erinaccus) has the surface beset with pointed 

 spines. The Moles (Talpa) and their allies, which are active 

 burrowers, have the limbs very short arid stout and provided with 

 extremely strong claws. The Jumping Shrews (Macroscelididcey 

 have slender limbs adapted to progressing by leaps on the surface 

 of the ground. 



The Chiroptera (Fig. 1055) 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 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 clawless. 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 



