LEl'OMDiB. 223 



Tlie OctodontiNjE have rootless molars, and usually 5 toes to each foot, 

 with large claws. They hare mostly large oars, and a long or moderate hairy 

 tail. They are of small size, and burrow. Their general aspect is inter- 

 mediate to that of chinchillas and voles. The chincliillas (CmNCHiLLiNiE) 

 have rootless molars and stout claws, as the last ; but the number of toes 

 is usually less. The tail is moderate and hairy, and held recurved, and 

 the ears are generally conspicuous. The clavicles are developed in this 

 and the last group. The chinchilla, Chinchilla laniger, whose fur is so 

 highly prized ; and the viscacha Lagostomus trichodactylus, are the best 

 known species. They burrow in the ground, and live in numerous socie- 

 ties. The hind-feet are usually considerably larger than the anterior, and 

 the animals hold their food, like the squirrels, between the short fore-paws. 

 All the species of the two last sub-families are exclusively confined to 

 South America. 



Fam. LEP0RIDJ3, Hares. 



Syn. Duplici-dentata, Van der Hoeven. 



Upper incisors 4 in number, there being two thin teeth placed behind 

 the anterior and larger teeth. Molars 5 or 6 on each side above, and 6 

 beneath on each side, rootless, and formed of two lamina joined together 

 by a transverse ridge of enamel. Fore-feet with five toes, hind-feet with 

 4, all with hairy soles ; nails long, compressed ; tail short or none. 



This family is distinguished from all other rodents by the possession of 

 a small additional incisor placed behind each of the large incisive tusks of 

 the upper jaw. These small teeth are considered to be the true incisors, 

 the front teeth, being as before stated, the representatives of the canines. 

 Their orbits communicate with each other through an aperture in the 

 septum as in birds. They have an enormous coecum lined internally with 

 a spiral layer throughout its entire length. There are only two well 

 marked generic forms, Lepus and Lagomys. 



Gen. Lepus, Linnteus. 



Cto.-Incisors, ^-=?; prfemolars, |=| ; molars |=|. The last mo- 

 lar above small and simple; ears typically very long; tail short, recurved. 

 Hind-legs much longer than the fore-legs. Their clavicles are imperfect. 



