272 BIRDS 



arm cannot assume because our hand has not so much 

 freedom of movement at the wrist. The long feathers that 

 grow upon the en(] i)ortion, or hand of the wang, are called 

 the primaries and those on the forearm the secondaries. 



The wings are attaclietl to tlie dorsal side of the body so 

 that the weight of the latter will lie suspentled from the 

 point of supjjort when tlie liird is flj'ing. 



Legs and feet. — Tlie legs of the sparrow are slender and 

 short, for they are not much used as organs of locomotion. 

 Sparrows hop rather than walk antl long 

 ^Jhigk legs are not needed. Like the ^^ings, the 

 legs are attached well toward the dorsal 

 side of the animal so that the weight is 

 suspended from the [toint of support. This 

 f/'ShanJc is of advantage to an animal that is obliged 

 to reach the groinid foi' all of its footl. 

 The liij) joints act as pivots on which the 

 'Foot body swings between the legs. 



Each leg consists of thi'ee parts : thigh, 

 shank, and foot (Fig. 1S6). The foot is 

 made up of the four toes and the ankle 

 -Bones wliicli is the scaly part of the leg not 

 of .sparrow's leg. covered liy feathers. Each toe is com- 

 posed of several segments and ends with a claw. 



Perching. — The sparrow belongs to the perching birds. 

 \^'henever the feet of the sparrow are placed on a support 

 and the body lowered, the toes will automatically close and 

 grasp the perch. A tendon running from the toes passes 

 u]) tlie leg in such a wa,)' that whenever the leg is bent, the 

 tendon is pulled so strongly that the toes are curved al)0ut 

 the sup[)ort. The closer the body gets to the support, the 

 more firmly will (he toes grasp it. Therefore, the sounder 



