38 SKETCH or THB HISTORY OF MAMMALIA. 



beneath ; the terminal tuft of the tail is black, merging 

 at the tip into white ; a white or whitish strip appears 

 on each of the buttocks below the base of the tail. 



The Dark-banded Jerboa. 



Of this Jerboa, which is figured by Shaw under the 

 name of " the Jerboa," we have never seen an example. 

 It is neither noticed nor figured by Lichtenstein, who 

 has published the best monograph of these animals that 

 has yet appeared. For ourselves we have no doubt but 

 that the original figure was taken from a specimen of 

 the Egyptian Jerboa, in which the abrupt border to the 

 white mark was darker than usual ; for in some instances 

 the back is washed with a dusky tint, which has a ten- 

 dency to assume wavy transverse bands, one of which, 

 on the haunch, as it is said, is occasionally distinct. 

 (Fig. 22.) 



With regard to the Alactagas, to' which we have 

 alluded, the typical species, the Siberian Alactaga (Dipus 

 Jaculus, Gmel.; the Alactaga, Buff.; the Siberian 

 Jerboa, Pennant), is distributed from Arabia, through 

 Persia, Tartary, and Turkey, and as far north as the 

 Volga and Irtish. It inhabits the plains and flat districts, 

 where it makes extensive burrows ; in general habits it re- 

 sembles the common Jerboa of Egypt, but is of larger size. 



Its food is stated to consist not only of vegetable but 

 also of animal substances, as small birds and insects ; and, 

 as we learn from Pallas, it spares not even its own species. 

 The subterranean habitations of these animals are ex- 

 tremely capacious, and formed about half a yard below 

 the surface of the ground. The passage leading to them 

 is of great length, and pursues a circuitous course, having 

 at intervals additional shafts or openings upwards, afford- 

 ing extra facilities for escape in the event of danger. 

 During the winter they hybernate ; retiring to their sub- 

 terranean chambers, they shut up the openings, and sink 

 into a complete state of lethargy. It is affirmed by 

 Gmelin, that when their burrows are opened at this 



