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THE AMERICAN NATUBALIST [Vol. XLIII 



falls between July eleventh and August sixteenth. Ta- 

 king it that the youngest larvae I have described are little 

 older than those of similar shape and structure described 

 by Brooks, and allowing a possible retardation on account 

 of the climate, we should conclude that the eggs were de- 

 posited pretty close to the first of July. That spawning 

 does not take place much before this I judge from the 

 fact that in 1905, while I was at Malpeque preparing the 

 station for removal, I took plankton at intervals between 

 June seventh and twenty-sixth and this shows no oysters 

 and but few mussels and clams. 



In the microscopic examination of the genital organs 

 for the purpose of determining the time of sexual ma- 

 turity, unless one examines a very great number taken 

 from many different localities, he may light upon an 

 abnormal number of individuals that are immature or 

 that have already spawned and so form a wrong concep- 

 tion as to the period of maximum spawning. Combina- 

 tion of both methods should give the best possible results. 



I have purposely attempted to disregard the statements 

 of others in order to be entirely unbiased as to my results, 

 and from the facts of my own observations I am disposed 

 to think that the period of maximum spawning falls in 

 July, but that a few may spawn earlier and a greater 

 number may straggle in later. 



It is a matter of regret to me that it did not fall to my 

 lot to begin the study of oyster larvae during the first 

 summer at Malpeque, for then I could have used the 

 second summer to verify, fill in details, and follow out 

 suggestions. I have looked forward ever since for an 

 opportunity to do so, and this is my chief excuse for the 

 delay in publishing these results. 



Chief points of importance resulting from the fore- 

 going work are : 



1. Larval oysters are present suspended in the water 

 of Richmond Bay, Prince Edward Island, in July and 

 August. 



