MAMMALS. 



591 



may be a foot in length, and as large in diameter as a lead-pencil. These 

 quills, large and small, are borne on the head, back, and tail ; and when 

 the animal is surprised, it does not attempt to run, but simply rolls itself 

 into a ball, with the head between the legs, and the spines standing out in 

 every direction. It is then a ticklish object to handle. In our species the 

 quills, though short, are exceedingly sharp, and each is finely barbed at 

 the tip, so that it is not readily withdrawn from the skin or clothing ; but, 

 on the other hand, every motion tends to force it farther in. If a man or 

 a dog approach one of these balls too closely, they are apt to rue their ven- 

 turesomeness. There is a quick, vicious flirt of the tail, and some of the 



Fig. 4.S2. — American porcupine (Erythizon clorsatus). 



spines are pretty sure to be left in the face of the one, or the hands or legs 

 of the other. This jerking, quick as a flash, is the source of all the stories 

 of shooting the quills. 



Besides these differences in the spines of the European and the Ameri- 

 can porcupines there is one of habit. Those of the Old World live in holes 

 in the earth ; those of the New (especially the species figured) are arboreal 

 in their habits, climbing trees with the greatest ease, but making but slow 

 and awkward progress on the ground. These forms, when abundant, may 

 do considerable damage in the forest, as they feed upon the barks of trees. 

 The South American species are even better adapted for a life in the trees 

 than is our form, for they have the tail prehensile. 



