28 POCKET GOPHERS OF THE UNITED STATES. 



Ill the State of Washington a large amount of money has also been 

 expended in poison for the destruction of Town sen el's Ground Squirrel 

 (Sperwophilus toicnsendi). Dr. J. W. Lockhardt, of St. John, Whit- 

 man County, under date of June 8, 1892, writes: *"I think it no exag- 

 geration to say that the farmers of this county (Whitman) spent $3,000 

 this year for the poison for this pest, and yet many acres of grain are 

 already destroyed." 



Evidently a bounty can be but a temporary expedient for the extermi- 

 nation of these or other animals. Even if a sufficient amount of 

 money were appropriated to completely exterminate a species in a given 

 locality, its numbers would soon be reduced to a certain limit where it 

 would cease to be profitable to hunt the animals, and the bounty would 

 consequently become inoperative. 



Bounties offered for the destruction of harmful species seldom accom- 

 plish the desired end, and if success does finally result it is only after 

 vastly larger expenditures than were at first thought necessary. After 

 a harmful species — the wolf, for example — has become rather scarce in 

 any section of country the offer of a bounty may lead to its complete 

 extermination j and to attain such a result, it is certainly good economy 

 to make the bounty large. Obviously, it is better to pay a large sum 

 at once for the last few pairs of wolves in a district than to offer a 

 bounty so small that it is little inducement to a hunter to spend his 

 time in their pursuit. In this latter case the wolves easily hold their 

 own for many years, or even increase slowly, while the aggregate boun- 

 ties paid will far exceed all expectation. In order to be effective a 

 bounty should be large enough to assure the destruction of the great 

 majority of the individuals during the first year, and this is especially 

 true of species which are very numerous and prolific. And yet the 

 amount of money required for the payment of bounties in such cases 

 would be so enormous as to make the plan impracticable. 



A full discussion of this phase of the subject may be found in a sec- 

 tion devoted to the question of bounties on the English sparrow. 



GEOGRAPHIC DISTRIBUTION OF THE POCKET GOPHERS. * 



The Pocket Gophers of the United States belong to three groups or 

 genera which may be distinguished by the upper front teeth : Geoinys, 

 having two grooves on the face of each of these teeth; Cratogeomys, 

 having a single deep groove, and Thomomys, having a single faint 

 groove or none. 



The area inhabited by the family stretches from the dry interior of 

 British Columbia and the plains of the Saskatchewan southward to 

 Costa Bica. In an east and west direction the group covers the conti- 

 nent from ocean to ocean, except that it is absent from the region north 

 of the Savannah River and east of the Mississippi Valley. The family 



* Abridged from a- monographic revision of the Geomyidw, N. Am. Fauna, No. 8,1895. 



