THE ANATOMY OF THE RABBIT. 437 



more numerous than those of any other mammalian order ; 

 and although they are adapted to very different modes of 

 life — some, like the " Flying Squirrels," floating through 

 the air by means of a parachute-like expansion of the in- 

 tegument between the fore and hind Umbs; others being 

 arboreal, like the ordinary Squin-els ; or among the swiftest 

 of runners, as the Hares; or strong buiTOwers, as the 

 mole-like Bathyergus ; or aquatic, like the Water-vole — their 

 structural differences are comparatively insignificant, and 

 the subdivision of the order into large groups is proportion- 

 ately diiiicult. 



Brandt has divided the Rodents according to their 

 cranial characters into Sciuromm-pha, Myoonorpha, Hystri- 

 comorpha, and Lagomorpha ; or. Squirrels, Rats, Porcupines, 

 and Conies, if we use these English names in a broad and 

 tribal sense. 



The student will find the Rabbit, one of the Lagomorpha, 

 to be a conveniently sized and easily obtained subject for 

 study. The following are the most important points to be 

 noted in its structure. The hairy covering of the body 

 extends over the palmar and plantar regions of the feet, and 

 into the interior of the moiith, so that there is a band of 

 hair on the inside of each cheek. There are five digits on 

 the fore foot, or manus ; but the poUex is smaller than the 

 others. The pes has only four digits, and the hind limb is 

 longer than the fore limb. The upper lip is large, flexible, 

 and cleft in the middle line; the large eyes are provided 

 with a third eyelid, and the pinns of the ears are very 

 long and mobile. The tail is short and recurved. The 

 male has a recurved penis, and on each side of it a scrotal 

 sac. The female has five pair of abdominal teats. In both 

 sexes perineal glands are present, consisting of a saccular 

 involution of the integument with rugose walls, into which 

 the duct of a special gland lodged at the side of the penis, 

 or of the clitoris, opens. 



There are nineteen dorso-lumbar vertebrae, of which twelve 

 are dorsal. Of the four sacral vertebi-se only the first unites 

 with the ilia. The dorsal vertebrae have weU-developed 



