1(5 



"CEYLON PEARL OYSTER REPORT. 



Many of the pearl oysters which we examined in the Gulf of Manaar in February 

 and March, 1902, and also those we have examined since, both in Liverpool and at 

 Ceylon, show numerous encysted parasites in various parts of the body. We have 



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if 



Fig. 1. Free-swimming larvae caught in the tow-net on Muttuvaratu Paar. 



found these cysts on the branchiae, in the mantle, in the liver and gonads, and 

 elsewhere amongst the viscera. Fig. 2, giving a transverse section (A) and a lateral 

 view (B) of a pearl oyster, shows a number of pearls and a few encysted parasites in 

 the positions where we most commonly find them. 



Fig. 2. A, transverse section of Margarififera vulgaris, and B, dissection from the right side, 

 to show the usual positions occupied by pearls and parasites. 



These cysts, though small, are usually visible to the eye, and measure from 

 0-13 millim. to 1*3 millims. in diameter. The contained parasite is not always in the 

 same stage of development, but is always, so far as our observations go, a young 

 Cestode worm. It is possible, however, that more than one species of Cestode is 



