80 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



it is necessary to review briefly some of the more important facts 

 in regard to the habits of the species. 



The breeding- season was found to be, for the most part, in June, 

 though it begins in May and ends in July. Clams spawn to some 

 extent also in other months, but in comparatively small numbers. 

 In the early spring (April) a meagre set is sometimes found, which, 

 from the uniform size of the specimens, seems to represent a 

 definite breeding season, probably in the late autumn. This set 

 is so sparse that it can hardly be considered to be of any economic 

 importance. (Report for 1899, page 23 ; report for 1900, pages 22 

 and 23.) 



The sexes of the clam are separate. The eggs are of micro- 

 scopic size and are laid in inconceivably great numbers wherever 

 adult clams abound, being extruded, without any means of protec- 

 tion, into the sea-water where they are fertilized. The young larv?e 

 which develop from these eggs are swimming animals of micro- 

 scopic size also, and are carried by the tides and scattered in every 

 direction until, after a period of several days (the exact duration 

 is not known), they strike upon some object like sea-weed, stones, 

 or the ground itself, and become attached by an apparatus exactly 

 comparable to the anchor-threads of the common mussel. But, 

 although the spat is everywhere present in the water, the density 

 of the set along the shore is very unequally distributed ; so that 

 in one area the little clams may be found in great abundance, 

 while in other areas, not far off, very few are to be found. It is 

 also true that these areas which are most favorable for catching 

 the spat are often not favorable for the future growth of the clams. 

 The significance of these peculiarities of the young clam for the 

 future of the clam industry cannot be overestimated. (Report for 

 1899, pages 23 to 27.) 



The problem of the rate of growth of the clams after they have 

 set has received a large amount of attention, on account of its 

 obvious practical value, and the results, illustrated by numerous 

 photographs, are given in the reports for 1899 and 1900. The rate 

 of growth varies greatly according to the locality, and the varia- 



