78 CEYLON PEARL OYSTER REPORT. 



and others extended the discovery to other pearl-producing oysters, and to 

 other parasites; but it is possible that Kelaaet knew nothing of these 

 papers, and that he made his discovery in regard to the Ceylon oysters quite 

 independently. He (and the Swiss Zoologist, Humbert, who was with him 

 at a pearl fishery) found ' in addition to the Filaria and Circaria, three other 

 parasitical worms infesting the viscera and other parts of the pearl oyster. 

 We both agree that these worms play an important part in the formation of 

 pearls ; and it may yet be found p>ossible to infect oysters in other beds with 

 these worms, and thus increase the quantity of these gems.' Thus we have 

 Kelaart, in 1859, definitely stating the possibility, in the case of the Ceylon 

 pearl oyster, of infecting other beds with the larvae of the pearl-producing 

 Platyhelminthian parasites in order to increase the quantity of pearls. 

 " Thurston, in 1894, confirmed Kelaart's observation, finding in the tissues and 

 also in the alimentary canal of the Ceylon oyster, ' larva of some Platyhel- 

 minthian (fat worm).' He figures (' Madras Mus. Bull.,' I., Plate II., fig. 1) 

 a section showing two of the parasites encysted between the alimentary canal 

 and generative tubes. Here the matter rested so far as the Ceylon pearl 

 oyster was concerned." 



Kelaart's work has been till recently somewhat neglected, and we therefore give 

 in a note* the whole paragraph which deals with parasites from his last Report.! 



The large number of oysters dissected during the fifteen months of Dr. Herdman's 

 and Mr. Hornell's expedition enable us now to furnish what is probably a fairly 

 exhaustive list of the Entozoa of the pearl oyster, seven in number. They comprise 

 one Cestode (Tetrarhynchus unionifactor, n. sp.), three Trematodes (Muttua 

 margaritiferaz, n. sp., Musalia herdmani, n. sp., Aspidogaster margaritiferm, n. sp.) 

 and three Nematodes, Ascaris meleagrinie, n. sp., Cheiracanthus uncinatus, and an 

 unidentified species of Oxyuris. 



* " I have not in this paper detailed some very interesting discoveries made since my last Report, on 

 the Anatomy and Physiology of the Pearl Oyster, believing that they are better fitted for a treatise on 

 the subject than to be embodied in a Report to the Ceylon Government, which must necessarily be 

 written in popular form. However, as this Report may, like the preceding ones, fall into the hands of 

 scientific men, I shall merely mention here that Monsieur Humbert, a Swiss zoologist, has, by his own 

 microscopic observations at the last pearl fishery, corroborated all I have stated about the ovaria or 

 genital glands and their contents ; and that he has discovered, in addition to the Filaria and Circaria, 

 three other parasitical worms infesting the viscera and other parts of the pearl oyster. We both agree 

 that these worms play an important part in the formation of pearls ; and it may yet be found possible 

 to infect oysters in other beds with these worms, and thus increase the quantity of these gems. The 

 nucleus of an American pearl, drawn by Mobius, is nearly of the same form as the Circaria found in the 

 pearl oysters of Ceylon. It will be curious to ascertain if the oysters in the Tinnevelly banks have the 

 same species of worms as those found in the oysters on the banks at Arripo." 



t Reprinted in the 'Proceedings of the Madras Government Revenue Department,' 17th February, 

 1864. 



