Family GEOMYIDAE 153 



gopher. At a distance, gopher mounds may be mistaken for those 

 of the mole. The gopher produces a mound, figs. 2 and 7, by 

 pushing the dirt from the mouth of the sloping entrancevvay in 

 such a manner that this dirt forms a relatively low, fan-shaped 

 mound. The mouth of the entranceway, which is on the low side 

 of the mound, is plugged by the last "load" of dirt; the "plug" 

 is a distinguishing characteristic of a recently constructed pocket 

 gopher mound. The mole produces a mound, fig. 6, by pushing 

 the dirt straight up from beneath the surface of the ground; 

 the loosened dirt cascades down evenly to form a cone with 

 relatively steep sides, like those of a volcano. In weathered 

 mounds, these differences are difficult to detect. A gopher 

 mound is 12 or more inches across, and a mole mound is about 

 10 inches. The pocket gopher never has subsurface runs that 

 hump up the dirt radiating out from the mound as does the mole. 

 Distribution. — The pocket gopher is abundant in the sandy 

 and black soils east and south of the Illinois and Kankakee 

 rivers, and in Madison County, fig. 86. In Illinois is the sub- 

 species Geomys bursarius illinoensis Komarek & Spencer. 

 The range of the species includes an irregular area in the center 

 of the North American continent, fig. 86. 



Fig. 86. — Known distribution, in the United States, of plains 

 pocket gopher. 



