BULLETIN OF THE UNITED STATES FISH COMMISSION. 339 



ON THE SEXUALITY OF THE COMMON OYSTER (O. edulis) AND THAT 

 OF THE PORTUGUESE OYSTER (O. angulata). ARTIFICIAL FECUN- 

 DATION OF THE PORTUGUESE OYSTER.* 



By UI. BOVCHON-BRANDELY. 



Twenty or twenty-five years ago the Portuguese oyster, indigenous to 

 the Tagus, did not exist on the coasts of France. It was acclimated in 

 our waters altogether accidentally. A vessel from Portugal discharged 

 its cargo so as to repair some damages it had sustained. The oysters 

 which it .carried were thrown into the Gironde, on the old Bone de 

 Richard ; here having met with the conditions favorable to their propa- 

 gation, they have multiplied in such numbers that, from the Point de 

 Grave to Richard, for a distance of 25 to 30 kilometers, they form a vast 

 bed, the extent of which will soon be limited only by the banks of the 

 river. 



The sexuality of this oyster differs essentially from that of the other 

 kinds common in our waters, the most widely diffused of which is 0. edulis. 

 The latter is hermaphrodite as established by Lacaze-Duthiers, Coste, 

 Davaine, Mobius, Eyton, Hart, and others. Is it a self-sufficing hermaph- 

 rodite? With respect to this nothing has yet been demonstrated. It is 

 highly probable that they are not self- fecundating, if we take into account 

 the fact that the genital gland rarely presents the two sexes at the same 

 degree of maturity. 



The Portuguese oyster, on the contrary, is unisexual. This fact is in- 

 contestable. We have opened a great number, taken at all phases of 

 the reproductive period, and all were exclusively male or exclusively 

 female. 



On the other hand, and contrary to that which occurs in the common 

 oyster, where fecundation is accomplished in the interior of the valves, 

 in the Portuguese oyster the eggs are expelled from the shell into the 

 water outside, where they meet with the fertilizing element. Never, in 

 fact, did we find either ova or embryos in the mantle of 0. angulata. A 

 fact which also goes far to prove this is the following: The eggs and 

 embryos of the Portuguese oyster develop in pure sea-water, while those 

 of the common oyster, at least during the whole of the period of gesta- 

 tion of the egg to the moment when the embryo abandons its maternal 

 shelter, cannot live outside of the liquid contained in the shell, a liquid 

 which, according to an analysis made in the laboratory of M. Berthe- 



* De la sexuality chez VHuitre ordinaire (O. edulis) et chez VHuitre portugaise (0. angu- 

 lata). Fecondation artificielle de V Huitre portugaise. Note de M. Bouchon-Brandehj, pre- 

 sentee par M. Berthelot. Comptes rendus heodomadaires des Stances de VAcademie des 

 Sciences. Fol.XCV, No. 5 (31 Juillet 1882), pp. 256-259. Paris, 1882. Translated by 

 John A. Ryder. 



