456 ZOOLOGY. 



small, and placed behind tlie principal pair, and these latter are grooved in 

 front. The upper incisors are double ; both the upper and under ones are 

 shorter, that is, less deeply implanted in the jaw than in other rodents, and 

 they are always white. The molar teeth are always rootless, five above 

 and five below, or six above and five below, on both sides of the jaws. 



Only two living genera compose this family ; a third is extinct. 



The genus Lagomys has no visible tail, short and rounded ears, short 

 hind legs, and the molars twenty in number, five above and five below on 

 each side. The species are generally of small size. One is American 

 {L. princeps), and inhabits the Eocky Mountains. Other species occur in 

 Siberia and Central Asia, as L. alpinus {pi. IIS, fig. 2 b). The pikas, as 

 the Lagomys are commonly called, although found in considerable number, 

 are not, strictly speaking, gregarious ; they occur only in alpine or sub- 

 alpine districts, where they form burrows in the ground, or sometimes take 

 shelter amongst the loose stones. Occasionally, Avhen the weather is cloudy, 

 they will quit these retreats in quest of food during the day, but the night 

 is their ordinary time of feeding. Their food consists of various kinds of 

 grass, and as in the high and cold regions which they inhabit the herbage 

 is covered with snow during the winter months, their instincts lead them 

 to lay up a stock for this season. Large quantities of dried grass and other 

 vegetable matters are collected by the pikas for their winter's consumption ; 

 these they pile up in the autumn, like small haystacks, which gradually 

 disappear as the spring approaches, unless, as not unfrequently happens, 

 these stores are robbed by the sable hunters to feed their horses. The 

 species of this genus seem to have been more numerous during the tertiary 

 epoch than in our days, and inhabited the southern part of Europe. Some 

 of the species have been made the type of the genus Anoe.ma of some Ger- 

 man palaeontologists. 



The genus Titanomys is extinct, of which several fragments of jaws with 

 prismatical teeth have been found in Germany. The upper molars are 

 provided only at the inner side with a very superficial furrow, and the 

 under ones, especially the posterior, exhibit characters wanting in Lagomys. 

 Only one species is known. 



The genus Lepus (the hares and rabbits) is characterized by the presence 

 of six molars above and only five below. The ears are large and elongated, 

 sometimes longer than the head itself; the tail short and very bushy ; the 

 hind legs powerful and much longer than the fore legs. Under this genus 

 come both the hares and rabbits, for no structural difference as yet has 

 been discovered between them ; the rabbits burrow, whilst the hares make 

 a kind of nest, called a form, on the surface of the ground, on which they 

 lie. The young of the rabbits, at least such is the case in the common 

 kind, are blind and naked when born; those of the hares are clothed with 

 hair and have the eyes open. By far the greater number of the species of 

 this genus agree with the hare in the habits noticed, and that animal may 

 therefore be regarded as the type of the genus. Destitute of means of 

 defence, the hares are timid, have remarkable power of flight, and to warn 

 them of danger, their senses of hearing, seeing, and smelling are usually 

 OCO 



