114 



The Pocket Gopher. 



replaced by a distinct genus Thomomys inhabiting nearly 

 the whole of the Rocky Mountains and Pacific regions. 



Kansas Species. In Kansas the dominant species of gopher 

 is G. bursarius. It is most abundant in the central and north- 

 eastern parts of the state, and ranges at least as far west as 

 the ninety-ninth meridian. Here it is partly, and a little fur- 

 ther west fully, replaced by the paler, sand-colored species, 

 G. lutescens. Whether the two species intergrade on the com- 

 mon border of their respective ranges I have not been able to 

 determine. At any rate, a discussion of this matter comes 

 within the province of a technical rather than an economic 

 bulletin. In no part of western Kansas have I found the plains 

 pocket gopher very plentiful. It is more scattering in its dis- 

 tribution than G. bursarius, being locally abundant only in the 

 gravel flats along the streams or among the sand-hills. The 

 harder soil of the buffalo-grass tracts has little attraction for 

 this burrowing animal. In the lower Arkansas valley of south- 

 central Kansas the species becomes as abundant, however, as 

 does G. bursarius in any quarter of the state. 



Distribution Map. If reports of depredations by pocket 

 gophers and demand for measures of repression and extermi- 

 nation can be taken as an index to distribution, it may be seen 

 from the accompanying map that Geomys bursarius is most 

 abundant in the region drained by the Kansas river and the 

 lower courses of its main tributaries. The area of greatest 



Distribution map. The number of dots represents the number of cans of gopher 

 poison sent out by the Station to various points in the state. The distribution of 

 the dots will thus serve to indicate roughly the local occurrence or absence of the 

 pest in destructive numbers. 



