Biological Papers. 111. 



worth considering in this relation; but the bull snake is common 

 enough on farms whose owners or tenants have had the wisdom 

 and forethought to protect the natural enemies of the destructive 

 rodent tribe. The snake is able to gain entrance to the gopher's 

 runway not only when the latter is temporarily left open, but also 

 by vigorously burrowing into the loose earth about a fresh mound. 

 In a case that came to my notice a large bull snake was surprised 

 in the act of trying to force his way into a burrow. The observer 

 quietly approached and for some minutes watched the reptile at 

 work. The modus operandi was to force the snout into the soil by 

 moving the head and neck from side to side, accompanied by a 

 slight rotary motion as the strong, rigid muscles of the body folds 

 came into play. At intervals, as the folds were crowded back upon 

 one another by this exertion, the front part of the body would 

 come out of the deepening excavation, scooping along a quantity 

 of earth in the curve between the head and neck. Only a short 

 distance from this snake another was crawling about over a gopher 

 hill, evidently seeking for an entrance or a favorable spot for forc- 

 ing one. Catching sight of the intruder, he became alarmed and 

 made off in some haste. When the observer quit the field the first 

 snake had burrowed to a depth of five or six inches and was still at 

 work. Once inside, the snake probably remains there for some 

 time and makes things interesting for the occupants. When one 

 is trapping gophers he will occasionally surprise a bull snake in the 

 act of trying to swallow the captured animal, trap and all. I have 

 also found this snake in the burrow of the striped spermophile, 

 helping himself to a ne'stful of the young of the latter, and have 

 seen him capture and kill the adult spermophile at the mouth of its 

 burrow. 



The little striped skunk {Spilogale interrupta) should not be 

 left out of account in discussing the natural enemies of the pocket 

 gopher. I had not supposed that these animals could make their 

 way through the burrows of the gopher, and had laid to the charge 

 of weasels a number of cases of killing and feeding on gophers im- 

 prisoned in steel traps. Finally I resorted to setting traps a second 

 time in the mouths of the burrows where a gopher had been partly 

 eaten, and in two instances succeeded in capturing a little striped 

 skunk. There was no question in either case but that the skunk 

 had entered the burrow at some point remote from the location of 

 the trap, for the opening through which the trap had been intro- 

 duced had been carefully covered with a board and loose earth; 

 this covering was undisturbed. In comparing this slender little 



