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vast bed thirty kilometers in length, and in breadth 

 only limited by banks of the river. This oyster is 

 found, too, on the coasts of OleroB and at the mouth 

 of the Charente. It breeds only to a limited extent in 

 the basin of Arcachon, and in this locality it present 

 the curious phenomenon of becoming sterile after a 

 time ; so that, but for the introduction of young oysters, 

 it would entirely disappear from the basin. It delights 

 in brackish and muddy waters, and indeed only breeds 

 in those beds in which the influence of fresh water is 

 distinctly felt. 



The experiments which have lately been success- 

 fully performed in the Laboratory of Embryogeny in 

 the College of France, and at Verdon on the left bank 

 of the Grironde, have conclusively established the pos- 

 sibility of the fecundation of the Portuguese oyster 

 by artificial methods. The peculiar characteristic of 

 this species is that their spat can only develop them- 

 selves in the open current, and that they are soon able 

 to move and to obtain for themselves that nutrition 

 which is necessary for their transformation into the 

 sedentary oyster. In view of this state of things, the 

 nature of the experiments was greatly simplified. It 

 must suffise to briefly point out here some of the 

 results obtained. They are not a little remarkable. 

 Some t<velve hours after the incubation of the ova, 

 artificially produced, had been commenced, it was 

 found that moving larvae were developed. Tiie suc- 

 cessful development of these into spat was the next 



