THE ALACTAGA. 



127 



that its motion is more like that of a bird skimming close to the surface of the ground than that of a 

 four-footed beast. 



The Jerboa is about six inches long, with a tail about eight inches in length exclusive of the tuft 

 with which its tip is adorned. Its upper surface is of a greyish sand-colour, like that of many other 

 desert animals ; the lower surface is white ; and the tail pale-yellowish above and white beneath, with 

 the tuft white, with an arrow-shaped black mark on its upper surface. 



Several other species of Jerboas are known, some from the deserts of North Africa, others from 

 the steppes of Central Asia. The latter region harbours some forms, which differ from the preceding, 

 among other characters, by having five toes in the hind feet, whereas the true Jerboas have only three, 

 but of the five toes only three are sufficiently developed to take part in the animal's progression. 

 The best known of them is the ALACTAGA (Alaetaga jaculas), a rather larger species than the Jerboa, 



and with a still longer tail, reddish-yellow with a greyish tinge above, white beneath and on the hind 

 legs. Its range extends from the Crimea and the steppes of the Don across Central Asia to the borders 

 of China. It walks upon all-fours, and when advancing quickly springs along after the fashion of the 

 Jerboa. Its food consists of all sorts of vegetable substances, 

 but it is especially fond of the bulbs of plants, and does not 

 refuse occasionally to eat insects, or even the eggs and young 

 of the birds which inhabit the steppes with it. The Alactagas 

 live in very complicated burrows, with many passages and 

 branches, and they are said always to make one passage from 

 the central chamber of their residence, which terminates close 

 to the surface of the earth at some distance, but is only 

 opened in case of danger, when the inhabitants escape through 

 it, the position of its intended aperture being previously un- 

 recognisable. In cold weather they sleep in their nests. The 

 female produces from five or six to eight young, in a nest lined 



with her own hair. Species of Alactaga occur not only in MOLAR TEETH OF THE JUMPING HARE. 

 Central Asia, but also in Arabia and North Africa. 



South Africa produces one species, the CAPE JUMPIXG HARE (Pedetes caffer), which constitutes a 

 distinct subfamily, PEDETIN^E, having four rootless molars on each side in each jaw, the metatarsal bones 



