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NATURAL HISTORY, 



part of the family. These either possess only three molars, or a very small additional tooth exists in 

 front of each series in the upper jaw. The molars are rooted, and diminish in size backwards in each 

 series. The cervical vertebrae are anchylosed ; the fore feet have the thumbs rudimentary, but 

 sometimes furnished with a small nail ; the hind feet have only three toes fully developed, and the 

 metatarsals are united into a single bone of great length ; the soles are furnished with elastic balls ; and 

 the tail is very long, well-clothed with hair, and tufted at the end. 



Of these pretty little creatures, which are in some respects singularly bird- like, about twenty 

 species have been recorded, and these occupy the whole of the Old World area of the family, except 



South Africa. The JERBOA (Dipus cegyptius) may serve as an example of this section of the 

 family. This is a most lively and active little creature, which inhabits the deserts of north-eastern 

 Africa as far south as Nubia, and extends its range into Arabia and south-western Asia. On these 

 arid plains, so scantily clothed with a few grasses and dry shrubs that it is difficult to conceive how 

 any animal can find a living on them, the Jerboa lives, often in numerous societies, and in company 

 with the few birds and lizards which enliven the wilderness. These animals dwell in subterranean 

 abodes consisting of many branched galleries, which they dig out in the hard soil not far from the 

 surface. The Arabs assert that these habitations are produced by the joint labour of the whole society. 

 They retreat into their burrows at the least alarm. The females are said to produce from two to 

 four young at a birth in a nest made in the deeper part of the burrow, and lined with hair pulled from 

 the under surface of her own body. When going along quietly, the Jerboa walks and runs by alternate 

 steps of the hind feet, but when there is occasion for rapid motion it springs from both feet at the same 

 time, covering so much ground at each leap, and touching the ground so momentarily between them, 



