3 o8 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



The skins are shipped in great quantities to Europe, where the 

 fur is used in making many articles such as boas, muffs, hats 

 and trimmings. The fur of the American rabbits is but little 

 used except by the Indians. 



There are two North American species of porcupines, an 

 Eastern one, Erethizon dorsatus, and a Western one, E. epixan- 

 thus. The quills in both these species are short, being only an 

 inch or two in length, and are barbed. In some foreign porcu- 

 pines they are a foot long. They are loosely attached in the 

 skin and may be readily pulled out, but they cannot be shot 

 out by the porcupine, as is popularly told. The little guinea- 

 pigs, Cavia, kept as pets, are South American animals related 

 to the porcupines. Because of the ease with which they can 

 be reared and handled, and for certain technical reasons, guinea- 

 pigs are much used in physiological and bacteriological labora- 

 tories for experimental purposes. The sacrifice in this way of a 

 few thousand guinea-pigs has aided in enormously increasing our 

 knowledge of the causes of and remedies for infectious disease. 



The pocket-gophers, of which there are several genera and 

 species mostly inhabiting the central plains, are rodents found 

 only in North America. They all live underground, making 

 extensive galleries. They are very destructive to such crops as 

 alfalfa, clover, grains, potatoes, and to many others, and often 

 cause the loss of thousands of dollars in orchards by destroying 

 the roots or girdling the trees and thus quickly killing them. 

 Gophers may be poisoned or trapped. Small bits of carrots, 

 potatoes, raisins, prunes or other substances may be poisoned 

 by placing a small amount of strychnine in them; an amount 

 equal to about half a grain of wheat is sufficient. The poisoned 

 baits should be placed in the main tunnel, not in the short 

 lateral tunnels that are used for bringing the dirt to the surface. 

 If placed in the lateral tunnels they may be covered over or 

 pushed to the surface where other animals or birds may find 

 them. Many special forms of traps are used, almost all of 

 them good if sufficient care is taken in setting them. When 

 the ground is not too dry success may often attend the use of 

 carbon bisulphide. Rags or waste may be saturated with this 

 liquid and placed in the hole which is then closed tightly, or 



