Pocket-gopher 581 



Since 1882 I have made personal investigations in parts 

 of Saskatchewan, Alberta, South-eastern British Columbia, 

 Dakota, Wyoming, Montana, Idaho, Colorado, New Mexico, 

 Arizona, and the mountains and dry parts of California, and 

 made numberless inquiries covering the western part of the 

 Mississippi drainage, as well as all the adjoining mountains, 

 without hearing of any earthworms excepting in localities 

 where they were introduced.'" 



Further, I am satisfied that, excluding the narrow humid 

 belt along the Pacific Coast, earthworms" are not native to any 

 part of America south of the Great Slave Lake or west of the 

 immediate Mississippi Valley. Probably the true earthworm 

 is not native to any part of North America. 



According to Darwin, there should be no vegetable mould loam 

 in this vast continental region. There exists, nevertheless, dant 

 a fine stratum of humus in all parts of it where there is moisture 

 enough to produce annual vegetation. The black loam in 

 Manitoba is from one foot to two feet thick, an amount proba- 

 bly not exceeded over any large area elsewhere in the world. 

 This is not a solid bed of decayed vegetation, but is thoroughly 

 mixed with the upper formation. 



There is no doubt, then, that, in the absence of earth- loam is 



COPHER 



worms, this mixing is done, as already stated, by a number of made 

 species of burrowing animals, but by far the most important 

 of these are the Geomyidce or Pocket-gophers. 



We have already noted the vastness of the area inhabited 

 by the Pocket-gophers, their ubiquity in that area, the great- 

 ness of their numbers, and the assiduity of their labours; 

 let us now look at the results in detail, and, finally, in mass. 



In Fig. 170 is shown the work of T. monticola, on a plot xumber 

 16 by 32 feet, found on the west side of Lake Tahoe, in Cali- mounds 

 fornia, September 23, 1899. In this the black spots show 

 where some animal had laid open the Gopher's burrow, 

 but there was nothing to say whether it was done from 



'" They have recently appeared in many highly cultivated parts of Manitoba. 



