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THE AMERICAN NATURALIST [Vol. XLII 



and devoured one of each. (2) It was frequently found 

 that one individual ate two oysters or clams in a day; 

 there usually being a long period of rest between meals, 

 the animal remaining buried nearly all the time, some- 

 times for as much as six weeks. (3) The character of the 

 erosion, noticed on the odontophore, indicates that these 

 mollusks are not shell borers. (4) When clams (Mya) 

 are the objects of assault, no difficulty is encountered in 

 gnawing out the soft parts, since the shells of the latter 

 gape slightly. The mussel and oyster, on the other hand, 

 are taken by surprise. The attacking gastropod thrusts 

 the margin of its own shell between the valves of that 

 of the prey, devouring the soft parts at leisure. In the 

 case of the " round clam" (Venus), B. carica uses yet 

 another method of attack. Holding the bivalve in the 

 hollow of its foot it brings the margin of its own shell 

 against the margins of that of its prey. By the con- 

 traction of the columellar muscle, the two are brought 

 into such forcible contact that a small piece is chipped 

 from the Venus shell. This is repeated many times, the 

 process lasting from seven hours to three days, with the 

 result that the crevice between the two valves is enlarged 

 to such an extent that the gastropod can devour its vic- 

 tim. (5) It is possible that the two species of Busycon do 

 not inflict so great damage upon oyster or clam beds as 

 has previously been reported. Field observations alone 

 can settle this point, however. 



Edgar D. Congdon, M.A., Austin teaching fellow, de- 

 partment of zoology, Harvard University, conducted in- 

 vestigations upon the fauna of the brackish waters in the 

 neighborhood of Woods Hole. A number of these ponds 

 were studied intensively, collections being made of their 

 fauna and flora, and determinations of density and tem- 

 perature being taken. A series of other ponds was like- 

 wise visited for purposes of comparison. Mr. Congdon 

 also acted as librarian of the laboratory, and considerable 

 time was devoted by him to classifying and cataloguing 



