THE RABBIT. 287 



109. The large eyes, guarded by an upper and a lower 

 eyelid, and by a third eyelid or nictitating membrane, ] 

 which can be pulled over the eye from its anterior (inner) 

 corner, and is strengthened by a plate of cartilage. 



1 10. The auditory apertures, one on either side of the 

 hinder region of the head, guarded by the large external 

 ears. 



in. The two rami of the mandible can be felt through 

 the skin, and, between their hinder ends, the movable 

 larynx ( 124). 



112. The vertebral column can be felt extending 

 from just behind the head to the extremity of the tail. 



113. At the sides of the anterior part of the trunk, the 

 ribs can be felt through the skin, and along the middle 

 ventral line of the same region the breast-bone or sternum. 

 These, with the corresponding part of the vertebral column, 

 enclose the anterior or thoracic region of the trunk. 



114. The posterior or abdominal region of the trunk, 

 enclosed at the sides and below only by skin and muscle, 

 except at its posterior extremity, where it is bounded by the 

 pelvis, the ventral portion of which, or symphysis 

 pubis, can be readily felt through the skin. 



115. The anus, a rounded aperture just under the root 

 of the tail, and bounded laterally by two naked patches 

 of integument, the perineal spaces, on which open 

 the ducts of the perineal glands (see 277), to the 

 secretion of which the animal owes its peculiar and unpleasant 

 smell. 



1 1 6. The urinogenital aperture, between the anus and 

 the symphysis pubis : in the male it is small and situated at 

 the extremity of tlie backwardly directed intromittent organ 

 or penis, in the female it is a large slit-like opening 

 or vulva. 



