10 THE SCALLOP FISHERY 



general conclusion at the end of chapter VI. It is realized that there 

 are various facts which still require further study, and that it will take 

 years of investigation to complete the history of the animal. The 

 anatomical description in chapter II. is by no means complete. The 

 object is merely to give the reader a general idea of the structure of the 

 animal, and to make clear the more intricate development of the various 

 organs as they appear in chapter III. No claim is made for marked 

 originality or for detailed work in the chapter on anatomy; the general 

 scheme given by Drew (1) is closely followed, and only a simplified 

 description is given. Likewise, the embryology of all the lamellibranch 

 mollusks have such a close similarity, not alone in the general course 

 of development, but even extending in some cases to very minute details, 

 that the description of any species might be applied equally well during 

 its early stages to any other closely related species. Thus, although our 

 work upon Pecten irradians was begun four years ago, and carried on 

 entirely independently, and is, we believe, the only work upon this 

 species which even professes to approximate completeness, its general 

 features closely parallel the admirable work of Drew (1) upon Pecten 

 tenuicostatus (the deep-sea scallop). Many of our results, therefore, 

 are entirely new for Pecten irradians, and, since they confirm the earlier 

 published observations on this and oilier species by Drew (1), Jackson 

 (4) and others, to whom due credit is given, are of use not alone as 

 confirmatory evidence; but since they contribute new observations and 

 original applications of these facts to the practical solution of how best 

 to develop and maintain our scallop fishery we trust that they are not 

 without value. The life history is given in narrative form and is not 

 explained in detail, as could be done by sectioning the developing eggs 

 and embrj'os. As it is the purpose .of this paper to present not only new 

 material but also a rather complete account of the life and habits of the 

 scallop, it has been frequently necessary to reprint or refer to previous 

 works on the subject. In most cases these observations have been 

 verified by our experiments, and are printed with the consent of the 

 authors. 



Courtesies. At the start of the investigation in 1906 there was found 

 a general lack of knowledge among the fishermen upon such important 

 points as the spawning season, rate of growth and length of life of the 

 scallops (Pecten irradians). Indeed, little literature on the subject was 

 available, Kellogg (5), Jackson (4), Ingersoll (8) and Risser (2) com- 

 prising all publications on Pecten irradians. Of these, Risser alone 

 dealt with the spawning, growth and length of life in his report upon 

 the life history and habits of the scallops in Narragansett Bay, Jackson 

 with the young scallop, and Kellogg and Ingersoll with the industries. 

 While the paper by Risser was of great assistance at the start of the 

 work, the diverse natural conditions in Massachusetts waters often ren- 

 dered our results at variance, and unfortunately made this excellent 



