38 CEYLON PEARL OYSTER REPORT. 



oyster. The bottom is suitable, and apparently the animals live naturally and grow 

 fairly well there. Most of the other bays and creeks we examined are useless because 

 of the large amount of mud present. We deposited in the harbour a number of living- 

 pearl oysters brought round from the Gulf of Manaar. They were enclosed in a wire 

 cage anchored and buoyed at a spot duly recorded outside Little Powder Island. 

 Mr. Hornell will examine these on his next visit to Trincomalee. 



Of the pearl oysters collected at Powder Island and on the reef oft* the ditch Co.'s 

 bungalow, 33 were at once examined as to the sexual condition 18 were males, 

 11 females, and 4 quite immature. The males ranged in size from 1-^ inch to 

 2\ inches, and the females from 1^ inch to 2^ inches. Some of these were ripe, 

 and we fertilised some ova with the spermatozoa. 



On the following afternoon we examined the shore in the other direction (south), 

 between the wharf and York Island, by means of small boat and wading. Here we 

 came again upon rock oysters, small land crabs and a large Ligia, also living corals 

 and Pinna. The bottom round York Island and towards the rocks near the Admiral's 

 house is hard and seems suitable for pearl oyster cultivation ; we found several dead 

 pearl oyster valves on the shores of the island. 



On the whole Trincomalee presents several distinct advantages as a locality in 

 which experiments in pearl oyster cultivation might be carried on : but on the other 

 hand it has several disadvantageous characters. As to the first, the pearl oyster 

 already lives there in a healthy state, and sometimes, at least, produces pearls. 

 Secondly, the locality is protected from the monsoons and sheltered in all weathers, so 

 that work and observations could lie carried on at all times of the year. Thirdly, 

 there are several places in the bay where the bottom is hard and seems suitable for 

 the attachment of pearl oysters. The greater part of the area is, however, very 

 muddy ; it is said that large quantities of clay are washed down by the rains, the 

 specific gravity of the water is rather lower than that usually found in the Gulf of 

 Manaar, and, so far as our observations show, the plankton or microscopic life floating 

 in the water is relatively small in amount and that will probably mean poor feeding 

 for the larger animals. The pearl oysters we found at Trincomalee struck us as looking 

 rather dwarfed or poorly nourished, and they were found to be sexually mature at a 

 much smaller size than was the case with those of the Gulf of Manaar. Hence while 

 experiments might be carried out at Trincomalee when impossible elsewhere because 

 of weather, the conditions of water and food are probably not so favourable as in the 

 Gulf of Manaar and would probably not lead to such active growth and shell 

 (including pearl) formation. 



The greater part of our last day (February 11th) at Trincomalee was devoted to 

 the examination of Lake Tamblegam, an enormous shallow sea-water area opening by 

 a narrow entrance from Great Bay. The sea-temperature at 7.20 a.m. in Great Bay, 

 oft' the entrance to Tamblegam, was 78 F. and the specific gravity 1*0160; at 9 A.M. 

 in Lake Tamblegam the temperature was 80 F. and the specific gravity 1*0145; at 



