ORDER RODENTIA. 151 



body, and that in some subjects there is a white spot upon 

 the body, sometimes a large black spot is found on the 

 epigaster. 



The habitat of the small Gerboa is more southern than 

 that of the two preceding varieties. It is found near the 

 Caspian, in regions where the Alactaga frequents, and on 

 the lower banks of the Volga and the Khymer, in regions 

 where the Gerboa Brachyura is also found. 



We shall leave to our readers to decide whether the 

 differences now described between these animals, which 

 after M. Pallas, we have persevered in calling varieties of 

 the Alactaga, are sufficient to constitute distinct species. 

 For our own parts, we rather incline to a different opinion. 

 None of the differences above-mentioned are as important 

 as those which exist among the varieties of the human 

 species. But we have already entered our protest very 

 frequently against the undue multiplication of species. 



We shall now proceed to other species of the Gerboa, as 

 given by other naturalists, though not actually authenticated 

 by the Baron. 



The Great Gerboa, or Dipus Maccimus of M. de Blainville, 

 was first observed by this clever naturalist in London, in 

 1814, in the Menagerie of M. Polito, in the Strand. It is 

 about the size of a small Marmot or Rabbit ,• its head is 

 large and rounded ; eyes very large, separated and altoge- 

 ther lateral ; the iris is black and the pupil round ; the 

 cheeks are wide ; the muzzle is short, very thick, with a 

 deep furrow that divides the upper lip in two, and is 

 extended to the partition of the nostrils. The ears are very 

 slender and transparent, not much covered with hair exter- 

 nally ; they are large, rounded at the extremity, with a kind 

 of dilatation, equally rounded at the exterior side of their 

 base ; the uose is complicated ; the opening of the nostrils 

 are oblique and semi-lunar, placed laterally and surmounted 

 with a deep fold, in the form of a V, the branches of which 



