BULLETIN OF THE UNITED STATES FISH COMMISSION. 345 



which joins the adductor muscle on its ventral side. In my report I 

 will give a detailed description of the organ of Bojanus of the oyster. 



If there is still the slightest doubt as to the hermaphroditism of the 

 oyster, my researches have shown that, at the time when an oyster is 

 sexually mature, it always functionates as a male as well as a female; 

 it is, therefore, physiologically dioecious. And when the eggs of one 

 oyster are fecundated by the spermatozoa of another, we need not be 

 surprised if the contact of the eggs and spermatozoa takes place in 

 the, interior of the animal. Likewise the fact observed by M. Lacaze- 

 Duthiers and by other authors, that the egg of the oyster is nearly al- 

 ways fecundated at the time of laying, is not surprising. The large 

 number of males also, that is to say, individuals functionating as males, 

 as stated by M. Davaine and M. Lacaze-Duthiers, explains itself. In 

 the case of the oyster, as with most other lamellibranchs, the spermatozoa 

 move and encounter the egg; "the water carrying the sperm in the 

 currents produced by the ciliary movements of the internal surface of 

 the mantle reaches the eggs;" that is, it gets into the genital duct. 



I think this view of the question is the only one which gives a rational 

 explanation of the facts. 



NOTE ON THE ORGAN OF BOJANUS IN ON IKE A VXKftlNI C A, GUIEEIN. 



By JOHN A. RYDER. 



In March, 1882, I first noticed what I supposed might probably be 

 the organ of Bojanus of the American oyster, but I could not then in- 

 vestigate the matter, so that it was allowed to rest for the time being 

 until a more favorable opportunity should occur to carry out more de- 

 tailed researches. In November, 1882, I first began to make prepara- 

 tions to study the subject by means of sections, the only method by 

 which it was believed possible to arrive at any valuable conclusions. 

 Although I have not yet traced the structure in question in its relation 

 to the pericardiac cavity and the openings of the generative organs, my 

 sections show essentially much the same details of structure as have 

 been described by M. Hoek. As that author observes, the literature of 

 the subject is silent in regard to this structure in the oyster, and of the few 

 allusions to the matter, one is by Huxley,* who says: "In Ostrea and 

 Teredo the renal organ seems to be present in only a very rudimeutary 

 form." He then alludes to the researches of M. Lacaze-Duthiers. That 

 it is present in a rudimentary form is the fact, as an examination of the 

 structure in question has proved. In Bronn's Klassen u. Ordnungen des 

 Thierreichs, III, Malacosoa, by Keferstein, on page 388, it is remarked, 

 in effect, that the organ of Bojanus in Ostrea is present as a mere ap- 

 pendage of the ventricle. In "Forest and Stream," under date of No- 



*Anat. I u vertebrates, p. 411, New York, 1878. 



