Dense clusters of small circular mounds or soil pimples are widely scattered on the treeless regions of western United States (Fig. 1). To a climax example of the mounds rising to a height of seven feet on Mima Prairie, Thurston County, Washington, Dalquest and Scheffer (1942) gave the name "Mima mounds." The origin of the mounds was laid to pocket gophers, members of the rodent family Geomyidae Gill, 1872. Later, one of the authors (Scheffer, 1947) extended the hypothesis to cover the "hogwallow" microrelief of the Central Valley, California, and the pimpled sea-terraces back of San Diego, California. A lively argument has persisted between two groups: those who champion the pocket gopher (Arkley and Brown, 1954; Dalquest and Scheffer, 1942; Koons, 1948; Price, 1949, 1950;