THE RABBIT 273 



canines, which are so prominent a feature in the carnivorous 

 mammals, are wanting; the back teeth, or grinders, are used to 

 chew the food. 



The mouth is a small transverse slit, with large lips which can 

 be retracted so as to expose the front teeth ; the upper lip has a 

 median cleft which divides it into a right and a left lobe (the 

 harelip). The nostrils are a pair of slits at the end of the snout. 

 The eyes are large, and each is protected by three movable eye- 

 lids : the upper lid, the lower lid, and the nictitating membrane, 

 or third lid. This latter lid is an opaque membrane at the inner 

 corner of the eye, across which it moves. The ears are large and 

 movable. 



The Neck. The neck of the rabbit is short, in correlation with 

 the short forelegs ; as in all land vertebrates, it is a flexible body 

 division which gives the head a wide range of movement. 



The Trunk. This region is made up of the thoracic, lumbar, and 

 sacral subregions, the first and third of which are rigid regions 

 and support the two pairs of extremities, whereas the second is a 

 flexible one. 



The thoracic subregion is the animal's chest; it contains the 

 heart and lungs, which are inclosed in a bony case composed of 

 the spinal column, the ribs, and the breastbone. It contains also 

 the pectoral girdle, by means of which the skeleton of the fore 

 limbs articulates with the trunk, and which consists mainly of the 

 two large shoulder blades, or scapulae. Four or five pairs of nip- 

 ples are present in the female animal, half of which are on the 

 thoracic subregion. 



The lumbar subregion is the animal's abdomen. Its walls are 

 supported dorsally by the spinal column, the transverse processes 

 of which are here very long ; laterally and ventrally they have no 

 bony support but are protected by the thick layers of the ab- 

 dominal musculature. This subregion forms the pivot of the 

 body: it is where the body bends when the direction of move- 

 ment is changed. 



The sacral subregion is the most rigid portion of the body except 

 the head. In it lie the hinder portions of the digestive and uro- 

 genital organs, together with the anus and the urogenital openings, 



