MAMMALS OF MINNESOTA. 155 



GENUS SCIURUS, LINN. 



Aside from obvious differences in habits, the true squirrels 

 may be distinguished from the chipmunks and gophers by the 

 broad head and curved dorsal outline of the skull. Skull short, 

 broad, cranial portion expanded, facial portion rather broad ; 

 malar bone nearly vertically expanded ; post- orbital process 

 produced and slender ; first premolar, if present, very small. 

 Pelage full, tail full and bushy, back never striped, no cheek 

 pouches. It is unnecessary to speak of the characteristics of 

 so familiar an animal. Every one whose boyhood brought him 

 within the influence of Nature at all must remember more than 

 one escapade in which this furry tree-farer played an important 

 part. 



Some fourteen species occur in America, some of which are 

 very closely allied. Our own state has but three species. 

 Central America seems to be the focus of the genus on this 

 continent, and here the species are not only the most numerous 

 and variable but the largest as well. Toward the north and 

 south the size diminishes, and a tendency is observed to depart 

 from the typical characters of the genus. The tail especially is 

 reduced. 



The following table copied from Allen's monograph will be 

 found useful: 



SYNOPSIS OF NORTH AMERICAN SCIURI. 



I. Tail very short and narrow, the caudal vertebrse alone 

 about two- thirds as long as head and body; tail to end of hairs 

 about one-seventh shorter than the head and body; premolars 

 -f, the first very small and often deciduous; a narrow, black, 

 lateral line; size small. 



1. Above greyish, mixed with yellowish or reddish, annu- 

 lated with dusky, often with a strong wash of ferruginous 

 along the middle of the back; below generally white, some- 

 times narrowly annulated with black; in one sub-species fulvous 

 below. Hob. Northern half of North America. S. hudsonius. 



I a). Above varied with black and yellowish-rusty; upper 

 surface of tail with hairs gray at the base and tips, with a 

 broad subterminal bar of black. Hob. Central portion of Rocky 

 Mountains and thence westward to Sierra Nevadas. 



var. fremonti. 



(b). Above dusky, strongly varied with reddish; upper 

 surface of tail with the hairs dark reddish brown at the base, 



