220 LLOYD'S NATURAL HISTORY. 



sentatives, form a group distinguished from all other Rodents 

 by the presence of a second small pair of upper incisors placed 

 immediately behind the large front pair. They are likewise 

 peculiar in that the enamel on the large upper incisors, in place 

 of being confined to their front surfaces, extends round to the 

 back, although it is still thicker in front than elsewhere. 



From the presence of the additional pair of upper incisors 

 this group is spoken of as the Duplicidenfata, whereas all the 

 other members of the Order are collectively classed as Simpli- 

 cidentata. In the young of the present group there are three 

 pairs of incisor teeth in the upper jaw, but the hindmost of 

 these are soon lost. 



As a family, the Hares and Rabbits are distinguished from 

 the Picas (Lagomyidce) by the collar-bones, or clavicles, being 

 imperfect, by the length of the hind-limbs being much in 

 excess of that of the front pair, by the presence of a short, 

 upwardly-curved tail, and the long ears. There are three 

 pairs of upper, and two of lower, pre-molar teeth ; and the 

 whole of the cheek-teeth are devoid of roots, and are divided 

 into parallel plates by transverse infoldings of the enamel. 

 The Family, which includes but a single genu?, has, with the 

 exception of Australasia (where Rabbits have been introduced 

 with most disastrous results), a cosmopolitan distribution. 



GENUS LEPUS. 

 Lepus, Linn., Syst. Nat. ed. 12, vol. i. p. 77 (1766). 



Since this is the only genus of the Family, it will suffice to 

 add to the above-mentioned characters that the fore-feet are 

 furnished with five, and the hind with four toes, and that the 

 soles of the feet are furred like the legs, while the inner sur- 

 face of the cheeks are likewise covered with hair. With the 

 exception of the Hispid Hare (L. hispidus\ all the species are 

 very similar to one another in external appearance, and all are 



