Figure 29. — The relationship of flat surfaces adjoining the surface of the soil to the initiation of burrows. This group of traps 
had been lined up near harborage box 6 for nearly a month prior to the taking of this picture on December 7, 1948. 
Note the small pile of diit to the right of the center trap. See figure 30 for a companion scene immediately after the 
removal of the traps. 
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