SEA-FISHERIES LABORATORY. 175 



Prof. Pi. Dubois has recently turned his attention to the 

 Mediterranean Coast. He found that the Southern French 

 mussel (Mytilus gallo-provincialis) forms pearls caused by 

 another Distomid, distinct from that of Brittany. He then 

 worked at the acclimatisation of a true Oriental Pearl- 

 Oyster (" Pintadine ") in French waters, and the artificial 

 production of pearls.* He brought the pearl-oysters from 

 the Gulf of Gabes, in South Tunis, to the marine laboratory 

 at Sfax, and caused them to multiply and increase in size. 

 The pearls produced in Tunis are small and very rare — 

 it is necessary to open 1,200 to 1,500 oysters to find one 

 pearl : but Dubois tells ust that by placing them on ground 

 where Mytilus gallo-provincialis becomes infested with 

 pearls and parasites, he very easily provoked the pro- 

 duction of fine pearls in the " pintadine " to such an extent 

 that three successive individuals opened contained each 

 two little pearls- 



This, if corroborated, is a remarkable circumstance 

 from several points of view. First it will, if it proves a 

 success, be a striking verification of what Kelaart in 

 Ceylon, fifty years ago, declared might be done. Secondly, 

 if the "pintadine" in question is really the same species 

 as the Ceylon Pearl-Oyster (Giard considers that it is not), 

 it is curious that a Distomid parasite should prove to be 

 so efficacious in setting up pearl-formation, since Mr. 

 Hornell and I found in the Gulf of Manaar that the 

 pearl-parasite is a Cestode of the genus Tetrarhynchus. 

 Thirdly it is remarkable that the parasite of the Mytilus 

 should transfer itself so readily to a new host belonging to 

 a distinct family. 



* Comba had, however, in 1S9S, introduced the same mollusc on 

 the south coast of Italy, and experimented in artificial pearl 

 formation. 



f Comptes rendus, Acad. Sci., 19th October, 1903, p. 611. 



