THE OYSTER. 57 



His paper was translated and printed April 19, 1883, 

 in the Bulletin of the U. S. Fish Commission. The 

 following extracts from this translation show the char- 

 acter of the methods which are employed, and the re- 

 sults which were obtained : 



"The mollusc, known under the name of the Portu- 

 guese oyster, has not existed upon our coast for more 

 than thirty years. It is superfluous to here describe 

 their external form, in that it does not recall that of 

 O. edulis. In respect to sexuality, the difference be- 

 tween these two molluscs is very great; most radical. 

 Oslrea edulis is hermaphrodite; 0. angttlata is uni- 

 sexual or dioecious. We have opened more than 

 10,000 in all phases of reproductive activity, and we 

 have not seen a single one of the latter of which the 

 sex was doubtful. They were all either exclusively 

 male or exclusively female." 



"No less marked is the difference in the mode of 

 reproduction. The eggs of the common oyster are 

 fecundated within the valves of the parent, apparently 

 within the openings of the oviducts; those of the 

 Portuguese species on the bosom of the waters. The 

 first cannot develop outside of the incubatory cavity 

 of the parent; the second undergo their development 

 in the open currents. The larvae of 0. edulis, in order 

 to live, develop and attain the errant or pelagic stage 

 of their existence, are dependent upon the albuminous 

 liquid secreted by the mother ; those of O. angtdata^ 

 more vigorous, more independent, and altogether 

 more active, transport themselves into the living 

 waters, to there take up the nutritive matters which are 

 necessary to transform them into spat. 



