502 HARES AND RABBITS chap, xv 



though truncate at the free extremity and hollow ; they represent 

 in a more rudimentary way the much stronger tuft at the end of 

 the tail of other Porcupines. It is a curious fact that this and 

 other Porcupines possess a mechanism for warning their foes 

 precisely comparal)le to that of the rattlesnake. There are 

 sixteen dorsal vertebrae. 



Sub-Oeder 2. DUPLICIDENTATA. 



The chief feature of this group is the existence of two pairs 

 of incisor teeth in the upper jaw, of which the inner are very 

 small and. lie behind the outer. In the skull the infra-orbital 

 foramen is small ; the incisive foramina are very large. The tail 

 is short or absent. 



Fam. 1. Leporidae. — This femily is distinguished from the 

 Lagomyidae by the long ears', by the tail, which is present, though 

 short, and by the longer limbs. There are six teeth belonging to 

 the molar series in the upper jaw, and tive of the same in the 

 lower. The clavicle is imperfect. 



The longest known genus of this family, Lcpns, was, until the 

 quite recent discovery of Romerolagns, the only genus. It is of 

 universal range, excepting Australasia and Madagascar, and con- 

 sists of about sixty species. These are the Hares and Eal)liits, to 

 the former being assigned the longer-limbed forms. 



As every text-book of zoology contains a more or less elaborate 

 account of the structure of the Common Eabbit, and as there is 

 but little structural difference between the members of the genus, 

 a short account of the generic peculiarities of Lepus will suffice 

 here. The fore-feet are five-toed, the hind-lind)s four-toed. The 

 hairy integument enters the mouth cavity, and the inside of the 

 cheeks have a hairy covering. The soles of the feet are, more- 

 over, hairy. The maxillary bones are curiously sculptured. 



The Common Eabbit, L. c-miiculiis, differs from the Common 

 Hare in the comparatively shorter ears and legs. The ears have 

 not, to so marked a degree, the black tips of those of the Hare. 

 The animal, moreover, produces naked young, and lives in burrows 

 of its own excavation. A difference in the structure of the 

 caecum, which distinguishes the Eabbit from the Hare, has been 



