INLAND FISHERIES. 03 



(c) Effect of vxitera of </ifferiiu/ dec/rces of )<alinify. 



In the transfer of clams just mentioned, it may be noticed that 

 the salinity of the water in the two localities is somewhat different. 

 In the Kickemuit the average salinity is about 1.019 ; at Woods 

 Hole, about 1.024:. As is the case with oysters, clams will live in 

 water which is brackish. At the salt pond near Wakefield, R. I., 

 for instance, the salinity I am informed by Dr. G. W. Field is 

 from 1.0049 to 1.0058 on the surface, and quite a number of clams 

 are to be found along its shores ; the density at the bottom may be 

 much greater than at the surface, however. 



(d) Enemies. 



One important fact which must be considered in developing an}' 

 method of clam culture is that the clam in its attached condition, 

 and when exposed on the surface of a bed, is destroyed in vast 

 numbers in many localities by one or two natural enemies. The 

 worst of these is that curse of the oyster culturist in northern 

 waters — the starfish. Many extremely interesting and important 

 observations in regard to this creature's habits of destroying 

 clams and other forms have been made during the past summer by 

 Dr. A. D. Mead. These observations show that the starfish, even 

 when minute in size, is terribly destructive to the young clams. 



Another enemy of the young clam is the oyster drill ( Urosalpinx). 

 I have taken many clam shells from the surface sand of the 

 bottoms, which exhibited the clam perforation filed by this creature. 

 Shells so pierced were from 8 millimeters to 2 centimeters or more 

 in length. As I have never found drilled shells in any great num- 

 bers in one locality, it would appear that the clam is not seriously 

 menaced by this foe. The adult clam, deep below the surface, is 

 probably not disturbed bj^ other enemies than man. 



SUMMARY. 



To recapitulate the principal points established in the above 

 description of the life-history of the clam, beginning after the 

 swimming larval condition : The In-eediugr season in Narragransett 



