298 DR. H. LYSTER JAMESON ON 



Most of these slides were preparations showing the parasitic 

 Cestodes in the tissues of the oyster, but there were also a number 

 of preparations of pearls, sectioned in situ in the tissues, showing 

 in all about 25 pearls, 21 of which showed their nuclei more or 

 less distinctly. The nuclei of these pearls were of very different 

 characters, but in no case could I identify a Cestode larva in the 

 centre of a pearl. 



(vi.) Three Specimens from the Persian Gulf. 



In September 1903, Mr. J. Calcott Gaskin, Assistant Political 

 Agent at Bahrein, Persian Gulf, sent me 32 specimens of 

 Margaritifera vulgaris from Bahrein preserved in alcohol. Out 

 of 20 of these that I opened, 3 contained pearls, which, from their 

 position, could obviously be classified as " cyst-pearls " (Herdman). 

 Two contained a single pearl each, that in the first being about 

 2"5 mm. in diameter, situate in the left mantle-lobe, above the 

 anterior end of the attachment of the gills [Preparation LXIV a], 

 that in the second [Preparation LXIY b] being about 1 mm. in 

 diameter and situate in the body-wall over the stomach. The 

 third specimen had two small pearls, about 2 mm. apart, in the 

 wall of the visceral mass, away from all muscle-impressions 

 [LXIV cj. All these pearls were decalcified in situ in the tissues 

 and sectioned. Their centres are described below. 



In addition to the above the following pearls were decalcified 

 and examined. More detailed particulars are given under the 

 descriptions of the centres of individual pearls, given below : — 



(vii.) Dry unlabelled pearls, probably from Ceylon, in the 

 British Museum, three examples were decalcified. 



(viii.) Mixed lot of pearls ; given to me by Mr. Max Mayer, 

 mostly ivova. Margaritifera vulgaris ; 115 were decalcified, of these 

 8 were sectioned. 



(ix.) A collection of pearls from the last Ceylon pearl fishery, 

 given to me by Mi". E. Hopkins. Fifteen were decalcified, 

 and four of these were sectioned, 



(x.) A collection of pearl-oysters, with pearls in situ, from the 

 Gulf of Kutch ; these are referred to above. Up to the time of 

 writing, 18 pearls from these specimens have been decalcified, 

 and 13 of them sectioned. 



(xi.) Two pearls from Margaritifera vulgaris, from the 

 Mediterranean, given to me by Professor Raphael Dubois. 



(xii.) Five pearls from Margaritifera vulgaris, from Kew 

 Caledonia, given to me by Professor L. G. Seurat. 



(xiii.) A pearl from Margaritifera vulgaris, from Madagascar, 

 given to me by Professor Seurat. 



(xiv.) Two pearls from Margaritifera vulgaris, from Papua, 

 from the Imperial Institute. 



