44 MAMMALIA. 



SCIURUS, Cuv. Squirrel proper. 



Hairs of the tail arranged upon the sides in the manner 

 of a large feather ; diet fructivorous ; habitation upon trees. 

 [Both continents.] 



PTEROMYS. Flying Squirrel. 



Feet with long bony appendages sustaining a lateral fold 

 of the skin. 



GENUS II. Mus, Lin. Rat. 



Linnaeus united under one head all the Rodentia provided 

 with clavicles which he could not distinguish by some exte- 

 rior mark. Six remarkable subgenera. 



ARCTOMYS, Gm. Marmot. 



Molars bristled, with conical joints, ten above, eight below ; 

 limbs short, with very strong claws ; tail rudimental ; four 

 fingers, and one tubercle, supplying the place of the thumb, 

 upon the fore-limbs; five behind. They live in societies, dig 

 burrows and form within them beds of grass, upon which 

 they pass the winter in torpor. Diet both insectivorous and 

 fructivorous. From this F. Cuvier has separated those Mar- 

 mots that have cheek-pouches. The Prairie Dog belongs to 

 this subgenus. 



Mus, Cuv. Rat proper. 



Six molars in each jaw ; four fingers and a vestige of a 

 thumb before, five behind. Tail long and scaly. Diet om- 

 nivorous ; voracious. .^ 



MYOXUS, Gm. Dormice. 



Eight molars traversed by furrows in each jaw ; inferior 

 incisors pointed ; tail very long, soft, and even tufted ; habita- 

 tion upon trees, where they live upon fruits ; become torpid 

 in winter. 



CRICETUS, Cuv. Hamsters. 



Six simple molars in each jaw ; five toes on all the feet ; 

 cheek-pouches; stomach with. double cavity; eyes large; tail 

 hairy, short and soft ; habitation in furrows of six or seven 

 feet deep, dug by means of their claws, and whither they 

 transport, in their cheek-pouches, considerable quantities of 

 grain. 



