14 CEYLON PEARL OYSTER REPORT. 



infected ground to less, carrying with them the larvae, either free or encapsuled, and 

 others, again, which may have escaped infection will go to areas where they run a 

 greater chance of encountering the parasite. It is important to note also, in view of 

 experiments in other parts of the Colony, that the Tetra/rhynchus parasites are not 

 only widely distributed over the hanks in the Gulf of Manaar, but also at other places 

 on the coast of Ceylon. 



Mr. Hornell* lias found Balistes with its Cestode parasite both at Trincomalee 

 and at Galle, and the sharks and rays also occur all round the island ; so that, in 

 short, there can be no doubt as to the probable infection of pearl oysters grown at 

 these or any other suitable localities. 



The details and illustrations of the parasitic life-history outlined above, and the 

 figures upon which our statements in regard to the oysters are based, will be given in 

 the special articles further on in this Report. But even when we have figured all our 

 specimens, have described all that we have seen, and have shown what conclusions 

 may safely be drawn, we feel sure that gaps will be left, and possibly doubts remain, 

 which can only be filled up and finally settled by patient work extending over years, 

 carried on by a competent observer resident in Ceylon, and having at his disposal a 

 laboratory and experimental tanks. A marine biologist working at the Galle Biological 

 Station can scarcely fail to add further details affecting the life-history of the oyster 

 and the prosperity of the pearl fisheries. 



During the two cruises of the " Lady Havelock," in our work on the parasites, 

 commensals, enemies, food, and other organisms associated with the pearl oyster, we 

 were brought in contact with many forms requiring identification, and some apparently 

 new to science. It was clearly our duty to collect all such and have them worked up 

 with the view of elucidating the fauna of the Gulf of Manaar and also of making any 

 necessary comparisons with other parts of the coast. Consecpiently, I am now able 

 to supplement this Report by a series of papers, written by specialists upon the 

 various groups of animals, which not only adds to the completeness of the pearl- 

 oyster work, but will also, I hope, be recognised as a welcome contribution to the 

 marine biology of Ceylon. 



The land fauna of Ceylon is very much better known than the marine. Dr. E. F. 

 Kelaart published in 1852 his important work, the ' Prodromus Faunae Zeylanicre,' 

 dealing with the mammalia, birds and reptiles. Mr. E. L. Layard has worked at 

 the ornithology and conchology, and we have his papers in the ' Annals and Magazine 

 of Natural History.' Harvey visited Ceylon in 1852 to collect the Ccelenterates 

 and Crustacea. Schmarda, a few years later, wrote on the worms. In Emerson 



* It is only due to my excellent .assistant, Mr. James Hornell, to state that our observations on pearl- 

 formation are mainly clue to him. During the comparatively limited time (under three months) that I 

 had on the hanks, I was mainly occupied with what seemed the more important question of the life- 

 conditions of the oyster, in view of the frequent depletion of particular grounds, 



