ORDER RODENTIA. 155 



these animals, mentions the names of ten different species, 

 some of which we shall notice here after M. Desmarest, the 

 others being altogether unknown. 



The first species is the Mus Tamaricinus of Pallas, com- 

 monly called the Tamarisk Gerboa. This animal is larger 

 than the common Rat, to which it has a considerable re- 

 semblance. The oblong head is terminated by a convex and 

 rounded muzzle; a membranous fold covers the nostrils; 

 long whitish silken hairs ; the upper lip is divided into two 

 lobes, and the under is very thick. The external face of the 

 incisive teeth is yellow, and the upper ones are marked by 

 a furrow, and slightly crenulated at their extremities ; the 

 lower ones are obtuse. 



TheTamaricin has a lively animated physiognomy, arising 

 from its large eyes ; the edges of the eyelids are of a clear 

 brown, and without hairs ; the ears are almost naked, 

 large, oval, and bordered with a kind of brown down. A 

 transversal fold, somewhat elevated, is observable at the 

 entrance of the auditory conduit ; the neck is short, and the 

 proportions of the body are similar to those of the Lerot. 

 The legs are strong, and the hinder longer than the fore, 

 though in proportion shorter in this species than the rest. 

 The fore-feet have four toes, without reckoning a sort of 

 tubercle which stands for a thumb. On the hind-feet are 

 five toes, and the thumb is longer than the external toe, 

 All the toes are naked and wrinkled underneath. There 

 are two callosities on the carpus, and three on the meta- 

 carpus. The tail is nearly cylindrical ; it is entirely covered 

 with hairs ; those on the extremity are the largest, and form 

 a brown tuft. 



The hair of the body is softer than that of the Rat, and 

 rougher than that of the Squirrel. On removing this hair, 

 we find a down of a leaden colour underneath attached to 

 the skin. All the upper part of the body is of a yellowish- 

 gray ; the sides have a shadow rather less deep, but towards 



