AVES 



271 



how well birds are protected by their colors, especially the fe- 

 male birds at nesting time. 



The Nervous System and Special Senses. The brain (Fig. 

 223) of birds is larger and more highly developed than that of 

 reptiles. The cerebrum and cerebellum are larger. The cere- 

 brum is smooth, but the cerebellum is convoluted transversely. 



Fig. 221. Tailor-bird (Orthot'omus suto'rius) and nest. (From Jordan 

 and Kellogg, " Animal Life," D. Appleton & Co., publishers.) 9 



The eyes of the bird are large, to meet the demands of far vision 

 in flight. There are two movable eyelids and a third membrane 

 called the nictitating membrane, which the bird can draw over 

 the eye by a peculiar muscular arrangement. This membrane 

 protects the eye from too bright light (Fig. 196). The pecten, 

 "a comb-shaped growth of the coroid into the vitreous body," 

 is a peculiar avian characteristic. The avian eye is character- 

 ized not only by the sharpness of vision consequent upon the 



