116 SKETCH OF THE HISTORY OF MAMMALIA. 



74, — Common Porcupine. 



In winter it appears to undergo a partial hybernation. 

 Sluggish and timid, the porcupine is yet enabled, clothed 

 in his array of spears, to repel the assault of enemies : 

 when driven to act on the defensive, he bends his head 

 down, turns his back towards his assailant, erects his 

 spines, and receiving the rash assault, pushes them forcibly 

 by the action of the whole body against the aggressor. 

 (Fig. 74.) The wounds thus inflicted are very severe, 

 and do not heal readily. The spines of the porcupine 

 are of two sorts : one sort being long, slender, and bend- 

 ing ; the other spines, concealed beneath the former, are 

 short, thick in the middle, and tapering to a sharp point; 

 they are ringed black and white. The length of the 

 short spines, which are the true effective weapons, is 

 from four to ten inches, and the point, which consists 

 of flint-like enamel, is somewhat compressed with two 

 slightly raised and opposite ridges, which when minutely 

 examined are found to be finely jagged. There is an- 

 other sort of furniture on the tail, namely a number of 



