250 MAMMALIA—PORCUPINE. 

The Severn River flying squirrel is much larger than the species described 
above, has a longer tail, and is of a different color. It is found near James’ 
Bay and Lake Huron. 
The Rocky Mountain flying squirrel lives in thick pine forests, and 
seldom leaves its retreats except atnight. It resembles the Severn River 
flying squirrel in form, though its limbs and tail are larger. It is of a 
vellowish brown color. 

THE PORCUPINE? 

Is generally about two feet in length, from the head to the extremity of the 
tail. The body is covered with spines, from ten to fourteen inches long, 


1 Hystrix cristata, Lis. The genus Hystriz has two upper and two lower incisors ; 
no canines ; eight upper and eight lower molars. Molars with flat crowns, but with 
ridges of enamel; head strong; muzzle gibbous; ears short, rounded; tongue with 
spiny scales ; fore feet with four toes and a rudimentary thumb; hind feet pentadactyle ; 
spines inore or less long, on the body, sometimes intermixed with hairs; tail sometimes 
vrehensile- 
