250 MAMMALIA—PORCUPINE. 
The Severn River flying squirrel is much larger than the species describea 
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. i 
THE PORCUPRINE? 
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Is generally about two feet in length, from the head to the extremity of tne 
tail. The body is covered with spines, from ten to fourteen inches long, 
1 Aystrix cristata, Lis. The genus Hystrir 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 anda rudimentary thumb; hind feet pentadactyle ; 
spines more or less long, on the body, sometimes intermixed with hairs; tail sometimes 
wehensile 
