4 o 



A Native Oyster. Ostrea Edulis. 



mystery to investigators of the origin of species. They have 

 made it clear that the American oyster, ostrca rirginica or 

 virginiana, and the Portuguese oyster, ostrca angulata, are 

 represented by the two sexes separately, but that the 

 common oyster, ostrca edit Us, which is the one cultivated in 

 the British Isles, is hermaphrodite, and produces from a 

 single oyster both female eggs and male cells, though 

 probably at different periods. 



In the common oyster that we know best, ostrca alulis, the 

 eggs fall into the water-tube of the gills and lodge there, 

 and the currents of water convey to them some of the male 

 cells, which on contact fuse together, the male cell losing 



