EXTERNAL CHARACTERS 



469 



hairy integument is continued on either side into the cavity 

 of the mouth. The eyes are protected by movable upper and 

 lower hairy eyelids, as well as by a hairless third eyelid or 

 nictitating membrane (compare p. 5), supported by carti- 

 lage and situated in the anterior corner of the eye, over 

 which it can be partly drawn : it corresponds to the little 

 red lump in the inner corner of the human eye. On the 

 upper lip and above and below the eye are certain very long 

 and stiff hairs — the " whiskers " or vibrissa, and behind the 



Fig. 121. — Rabbit. 

 Lateral view of skeleton with outline of body. (From Parker and Haswell's 

 Zoology^ 



eyes are a pair of long and movable external ears or pinna : 

 these are supported by cartilage and are somewhat spout- 

 shaped, leading to the external auditory openings. 



Below the root of the tail is the anus, and in front of 

 and below this, the urinogenital aperture, the space between 

 them being known as the perinceum. On either side of these 

 apertures is a hairless depression of the skin on which open 

 the ducts of ^& perinceal glands, Ae secretion of which has 

 a strong and characteristic odour. In the female the slit- 



