218 



FIRST LESSON'S IN ZOOLOGY. 



point downwards. We notice some long hairs inside of the 

 ears, and a few over each eye, but there are no true eye- 

 lashes or eyebrows. The whiskers consist of about a dozen 

 very large stiff hairs on each side of the upper lip; these ex- 

 tend out beyond the body and are very sensitive, so that the 

 cat can feel her way through narrow places. A cat is very 

 dependent upon her whiskers for a knowledge of what is 

 near her. Every part of the body, however, is not covered 

 with hairs; they would be useless on the end of the nose, on 

 the lips, and the foot-pads, which are naked. How useful 

 the hair really is to a mammal is proved by the fact that 

 all, with rare exceptions, are hairy. 



The cat's eyes are large and rather wide apart, and placed 



Fio. 223. Cat's muzzle, with " whiskers" and naked skin about the nostrils. 



in roomy orbits; besides the upper and lower lid, there is, 

 as in the birds, a nictitating membrane which rises from the 

 inner angle of the eye, and can be drawn over the eyeball. 

 The red portion lining the eyelids and corners of the eye is 

 called the conjunctiva ; over the ball of the eye it is trans- 

 parent and colorless. The " pupil " is the central part of 

 the eye; it is surrounded by the " iris/' which varies much 

 in color and can contract in the light, or expand in dark- 

 ness. In a bright light the iris closes so as to leave only a 

 narrow vertical chink. We thus see how perfectly the cat's 

 eye is adapted to its habits of night prowling. 



In none of the backboned animals previously mentioned 

 is there a well-formed outer ear; but that of the cat is large 



