222 NEW ZEALAND NATURE-STUDY BOOK 
These are extremely sensitive, and enable the animal to 
feel its whereabouts in the dark, in much the same way 
as the whiskers of the Rabbit assist it in creeping along 
dark narrow passages. 
The Eyes. Cats are nocturnal in their habits ; hence 
their eyes are very sensitive to light, the pupils becoming 
large or small according as the light is weak or strong. 
The pupil is really quite clear and transparent, and only 
appears dark because we are looking through at the black 
coat, the retina, at the back of the eye. Surrounding 
the pupil is a coloured ring, the iris, which regulates the 
supply of light by expanding or contracting. When the 
light is strong, this curtain grows larger reducing the pupil 
to a mere vertical slit ; in the evening or at night, when it. 
is of advantage to admit as much light as possible, the 
iris contracts and enlarges the pupil. We sometimes say 
that “cats can see in the dark ;” by this we mean that they 
can see when there is too little light for us to do so—no 
animal, however, can see when light is entirely absent. 
The eye of the cat has a brilliant lining, which, reflecting 
the dim light of the evening, is able to reinforce the 
supply available. 
The Ears, that is the external ears, are small and 
erect—and covered both inside and out with hair—that. on 
the inside, however, being much less close than the outside 
covering. The sense of hearing is so keen that to steal 
upon a cat unawares is almost impossible. Pupils will 
know from experience how quickly a cat can hear the 
slightest sound. 
The Teeth are sharp and pointed; in each jaw there 
are six small chisel-edged teeth, and two long curved 
canine teeth, one at each side, and four sharp molars. The 
molars, instead of being broad-topped like those of most 
mammals, have sharp cutting edges and overlap each other 
