•276 BIRDS 



has three licls, an luuler anrl an upper Hfl and a third lid 

 that can l)e (h-awn over the whole eye, known as the nictitat- 

 ing membrane. Tlie sparrow has no external ear, but the 

 opening to the internal ear may l)e seen just back of and a 

 little lielow tlie e}-e. It is coveretl by a tuft of loose feathers. 

 The sense of hearing is keen, and Ijirds tlepend upon their 

 sense of sight and of hearing to detect their ejieniies. The 

 sense of touch is distributed all over the body. 



Life history of the sparrow. — The sparrow builds its 

 nest in almost any nook or crannj' alDout the cornices of 

 buildings or among the branches of trees. The nest is a 

 simple one maile of stems and twigs mixed with hair and 

 grass and lined witli feathers. Six to ten eggs are laid 

 at a time and there are hve or six broods in a season. 

 Sparrows multiply very rapidly, and were it not for rats, 

 mice, snakes, cats, etc., they would be much more al)undant 

 than they are. They are exceedingly hardy birds and crowd 

 out otlier kinds. 



The sparrow's adaptation to flight. — In the first place, 

 the general form of the l:)0(h' is conical, Ihus offering as 

 little resistance to the air as possilile. The covering of 

 feathers give buoyancy to the body and aid greatl>' in sus- 

 taining tlie weight of tlu> animal in the air. The wings 

 are placed near the dorsal side of (lie body so that the 

 weight of the animal wiW liang susi)ended from the point 

 of sujjpoi't and lessen (he lial)ility of being overtin-ned in 

 the ail'. The breastl)one is furni.shed with a ridge, or keel, 

 and the sides are long and slo]iing to afford space for the 

 attachment of the ])o\\(Mful muscles that move the wings. 

 Moreover, the large feathers on the wings and the manner 

 in which they are arranged increa,se the surface of these 

 organs of flight and enaJ)le them lo pie.sont additional re- 



