BOSTON ZOOLOGICAL SOCIETY. 17 



15. Fiber zibethicus, Cuv. Muskrat. This is an 

 abundant and well known species occurring throughout 

 the state. It is a peculiar looking animal, and the largest 

 of our Mw^idce. On the approach of cold weather it has 

 the interesting habit of building large dams, in the same 

 manner as the beaver, in the rivers which it inhabits. 

 These structures are always conical in shape, and inva- 

 riably protrude a little distance from the water. Great 

 numbers of them can often be seen in the same stream. 

 By many the appearance of these " dams " is thought to 

 indicate a cold winter, Nearly black individuals of this 

 species are occasionally taken, although such variations 

 from the usual color are of rare occurrence. 



8PALAC0P0DIDJE. {American Porcupines.) 



16. Erethizon dorsatus F. Cuvier. White-haired 

 Porcupine. This species is now probably nearly extinct 

 in Massachusetts. Mr. Allen gives it as " occasional on 

 the Hoosac ranges." I have never seen it in this state. 



In various parts of Northern New England the Porcu- 

 pine occurs abundantly, and in the less settled districts 

 appears to supplant the rat. It frequently infests old and 

 deserted houses, and, as its teeth are very powerful, does 

 considerable damage by gnawing. The sound it makes 

 when so doing is very loud. It is nocturnal in its habits, 

 and during the day lies concealed in hollow logs or in 

 holes in trees, not leaving its hiding place until well into 

 the evening, generally not until nine or ten o'clock, and 

 ceasing its depredations some time before daybreak. In 

 Northern Vermont I have seen houses where the steps 

 have been entirely gnawed away by these animals. 



The quills which cover their backs have always been 

 celebrated. They vary in color from black to different 

 shades of gray and even white, are very sharp, more or 

 less barbed at the point, and so resisting that I have known 

 a bullet to glance from the backs of the animals. 



