38 



Fortunately I examined the oysters which were brought 

 in by the boats ; for, as events turned out, it was my only 

 opportunity of making an examination. I was at once struck 

 with the fact that the shells of the oysters presented an 

 entirely different appearance to those of the Tholayiram Par 

 (Tuticorin). For, whereas the latter were enveloped in dense 

 masses of algse (sea weeds) and the surface of the shells was 

 covered by variously coloured branching and sessile encrusting 

 sponges, the surface of the shells of the former which was 

 uppermost during life was, in very many cases, covered over 

 by stony corals, which formed either encrusting masses or 

 branching tufts. Specimens of the shells, with their accom- 

 panying corals, many of which were to be seen lying strewn 

 along the sandy shores of the bay, discarded by natives after 

 extraction of their contents, have been deposited in the 

 Madras Museum. Further examination of these coral-bear- 

 ing shells would be of interest ; for, as the age of the oysters 

 can be approximately fixed, a very good idea could be 

 obtained, by weighing and by observation of the size of the 

 corals on oysters of different ages, as to the rate at which the 

 corals grow.^ Chemical analyses of the sea water over the 

 Ceylon and Tuticorin pearl banks, especially with reference 

 to the percentage of lime salts, should also be carried out. 



As regards my observation that the Tuticorin shells were 

 covered with algse while the Ceylon shells were encrusted 

 by corals a Ceylon correspondent writes as follows : — 



" From the fishery of 1887 we took away specimens, very 

 beautiful to look at, but several of which showed that the un- 

 fortunate animals inhabiting the shells had their residences 

 converted into their tombs by the fatal industry of the coral 

 animals. But our specimens were not obtained from the Moda- 

 ragam Par, which was that we saw fished, and the shells taken 

 from which are always covered with red colored algee, and never 

 with corals. We gathered our coral-covered specimens from the 

 mounds of dried shells on the sea-shore, and learned that they 

 had been taken in a previous fishery from another bank." 



The mid-day heat at Dutch Bay was very intense, the 

 sand getting so hot that even coolies could "not walk on it, 

 and the blue-bottle flies were an intolerable nuisance from 

 early morn till sun down. The plague of flies at the Ceylon 



. > The rate of growth of corals is fully discussed in Darwin's Structure and 

 Distribution of Cora! Reefs, 3rd ed., 1889, 



