82 INLAND FISHERIES. 



period of its early life. The smaller forms wliicli I was able to 

 find in the seaweed above the bottom were minute in size, some 

 being but A of a millimeter in length. In every individual there 

 Avas to be found a well developed byssus, which afforded a rather 

 firm hold to the filaments of the weed. All the clams in the weed 

 of course maintained their position by the same means, and the 

 largest of these which I found, when I made my first examination 

 early in July, was 7 millimeters in length (a little more than ^ of an 

 inch). A search early in August revealed several somewhat larger 

 than this, each attached by a byssus, and in the mud of the bottom 

 also many were obtained, some of them from 10 to 13 millimeters 

 in length, which still possessed a well developed byssal thread. 



In the note by Professor Ryder, spoken of above, a statement in 

 regard to the size of attached individuals is not quite clear. He 

 says : " As they grew larger it was further supposed that they 

 were held fast in their unusual position by the fibres and cement 

 substances secreted by the mantles of their ascidian neighbors, 

 and thus were sufi^ered to attain a considerable size (from two 

 to fifteen millimeters). - * ^ However, further investigation 

 showed that in this I was in error, for after a careful search, a few 

 individuals were found from which a single byssal thread was 

 found to proceed." From this statement it does not appear 

 positively that any individual fifteen millimeters long was seen to 

 have a byssal thread attaching it to a floating body, though such 

 possibly may have been the case. 



Beginning work early in July, I was unable to find sexually 

 mature adults either in Narragansett Bay or at Woods Hole, the 

 breeding season evidently coming earlier in these localities, 

 probably in May and June. That a few individuals still continue 

 to discharge sexual cells late in July, however, we have evidence 

 in the fact that even in Aug'ust there appear on the seaweed a 

 few very small forms which must be comparatively young. 



We are led to the conclusion, then, that the free-swimming 

 embryos attach themselves to foreign objects, such as the sea- 

 weed Enteromorplia, to eel-grass, TJlva, stones, and other bodies, 



