RODENTIA. 85 



These two large species appear to have originated in the East, and have been 

 transported in ships, together with the mouse, to all parts of the globe. 



GKRBILLUS, Desmarest. 



The Gerbils have molars that differ very little from those of rats, merely 

 becoming sooner worn, so as to form transverse elevations. Their superior 

 incisors are furrowed with a groove ; their hind feet are somewhat longer in 

 proportion than those of rats in general, and their thumb and little toe slightly 

 separated. Their tail is long and hairy. The sandy and warm parts of the 

 eastern continent produce several species. 



G. Indicus. (The India Gerbil.) Size of the fat dormouse ; fawn-coloured 

 above, whitish beneath ; tail longer than the body, and blackish at the end. 

 The 



MERIONES, Fred. Cuvier, 



Which we separate from the other Gerbils, have the hind feet still longer ; 

 the tail nearly naked, and a very small tooth before the superior molars; 

 characters which approximate them to the Jerboas. Their upper incisors are 

 grooved like those of the Gerbils, and their toes also are similar. There is a 

 small species in North America, the 



Mus. Canadensis, Penn. (The Jumping Mouse.) Size of a mouse ; fawn- 

 coloured grey ; tail longer than the body. In summer a very active animal, 

 which in cold weather shuts itself up in its burrow, and passes the winter in a 

 state of lethargy. 



CRICETUS, Cuvier, 



The Hamsters have nearly the same kind of teeth as rats, but their tail is 

 short and hairy, and the two sides of their mouth are hollowed into sacs or 

 cheek pouches, in which they transport the grain they collect to their subter- 

 raneous abodes. 



C. vulgaris. (The Common Hamster.) Larger than the rat; of a reddish- 

 grey above, black on the flanks and underneath, with three whitish spots on 

 each side. A spot under the throat, and another under the breast white; some 

 individuals are all black. This animal, so agreeably varied in colour, is one 

 of the most noxious that exist, gathering large quantities of grain, with which 

 it fills its burrow tliat is sometimes seven feet deep. It is common in all the 

 sandy regions, that extend from the north of Germany to Siberia. 



This last country produces several small species of Hamsters described by 

 Pallas. 



ARVICOLA, Lacepede. 



The Arvicolae, like the rats, have three grinders every where, but without 

 roots, each one being formed of triangular prisms, placed on two alternate 

 lines. They may be subdivided into several groups, viz. 



FIBER, Cuvier. 



The Ondatras, or Musk Rats, having semi-palmated hind feet, a long scaly 

 and compressed tail, of which one species only is well known : 



F. vn/ftaru. (The Canadian Musk Rat, or Ondatra.) As large as a rabbit 



