102 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Grypluca and the ordinary oyster finding themselves face to face, the 

 latter must inevitably succuml). The Portuguese mollusk is incoutest- 

 ably more liardy, more resisting, and also, it seems to me, more prolific. 

 The facility "with which it propagates itself is, in fact, very remarkable. 

 It is known in what manner the Portuguese oyster took possession of 

 a part of our coast. Some hundreds of these mollusks, accidentally 

 introduced at the month of the Gironde, soon formed considerable beds. 

 I have this present year seen the collectors placed on the shores of the 

 Island of Oleron covered almost exclusively with Portuguese spat. I 

 think then, IMr. Minister, tliat in most cases the culture of the Gryphcea 

 practiced in the vicinity of parks of common oysters may be accom- 

 panied with grave disadvantages. 



And yet, I must repeat, I have no evidence at Arcachon of the en- 

 croachment of the Portuguese oyster. Here is, moreover, the entirely 

 disinterested testimony of M. Lhopital, naval commissary, to whom I 

 communicated my fears upon seeing the introduction of the Portuguese 

 oyster in Arcachon Bay daily increasing. M. Lhoijital wrote to me 

 lately : 



" Before the question of hybridization arose, this question of the in- 

 vasion of collectors by the Portuguese oysters had already agitated the 

 maritime population of Arcachon Bay. Some park-owners had even 

 asked that the introduction of this oyster into our waters be strictly 

 lirohibited, and at the beginning of 1878 the minister caused an inquiry to 

 be made upon the subject. It is now recognized that the danger jiointed 

 out was not serious. For more than twenty years there have been con- 

 tinuously introduced great quantities of Portuguese o;^sters, coming 

 either directly from the mouth of the Tagus, from the bay of La Corogne, 

 from England, or from the mouth of the Gironde. Well, excepting per- 

 haps one or two years, the reproduction of Portuguese oysters in the 

 bay has been noticed to be very slight. The collectors that have been 

 taken up this year contained none of them, so to speak, and I have had 

 much difficulty in finding any specimens of Portuguese oysters on the 

 reserved beds." 



M. Lhopital attributes this lack of reproduction on the part of the 

 Portuguese oyster in Arcachon Bay to the purity of the water and to 

 the absence of mud. I am much disposed to accept the exi)lanation of 

 the naval commissary. It is, indeed, remarkable that wherever one 

 sees the Portuguese oyster propagate itself rapidly one can aver also 

 the presence of mud in suspension in the water. However, it appears 

 to me, Mr. Minister, that the oysterculturists of Arcachon should take 

 some precautions and watch attentively what takes place in their 

 l^arks. Only a slight change in the currents would be sufficient to 

 cause the water to become charged with mud and the Portuguese fry 

 to invade the collectors. I do not think, however, that the state needs 

 to interfere in this matter otherwise than by its advice. 



Such is, at the ijreseut hour, the condition of the oyster cultural in- 



