256 ESSENTIALS OF ZOOLOGY 



The description which follows will be found to apply equally 

 well to the other species of Lepus, e.g. the hare, L. timidus, the 

 mountain hare, L. variabilis, and, indeed, to most mammals. 



EXTERNAL CHARACTERS. The rabbit is bilaterally symme- 

 trical and is resolved into head, neck, trunk, and tail, and there 

 are two pairs of limbs ; the whole body is covered with hair. 

 The head presents the characteristically long ears. The mouth 

 is bounded by fleshy lips interrupted above by a cleft leading to 

 the nose, a feature which gives mobility to the upper lip and is 

 at the same time a persistent embryonic state. The typical 

 rodent teeth are to be noted ; their description will follow. The 

 muzzle is occupied by the paired anterior nares and bears 

 prominent hairs, called vibrissae, which are not merely tactile 

 but are believed to assist in vision. The eye is protected by 

 upper and lower eyelids and a large nictitating membrane 

 which may be pulled over the eye from the inner canthus. 



The perineal region is covered by the tail. It presents the 

 anal opening of the intestine and the separate opening for 

 the urinogenital organs. The external appearances are very 

 similar in both sexes, but the female opening will be observed 

 to be a slit forming the vulva on the ventral wall, of which the 

 clitoris is a small conical projection. In the male the penis 

 is only slightly projecting ; it is covered by the prepuce, which 

 forms a preputial pouch for its reception. At its base a 

 pair of scrotal sacs form small projections. A pair of bare 

 patches will be observed in both sexes, which are occupied 

 by the orifices of the perineal glands, the secretion of which 

 gives the rabbit its characteristic odour. In the female the 

 ventral aspect of the body is occupied by a series of five pairs 

 of mammary glands, and each is marked by a projecting teat. 

 They are very small in the male. 



The limbs have the usual mammalian segments. The fore- 

 limb possesses five digits and the hind-limb four digits, the 

 internal digit being absent. All the digits terminate in horny 

 claws. The hinder limbs, which are the main organs of loco- 

 motion, tend to be large in the genus Lepus, and the contrast 

 between the two pairs may be great, as in the jumping hare. 



INTERNAL STRUCTURE. Skeleton. For the study of the 

 mammalian skeleton it is not necessary nor desirable to select 



