BIOLOGICAL SURVEY OF TRINCOMALEE HARBOUR. 31 



two, and in the locality wliere Herdman found the sponge in 

 abundance in 1902 I obtained one specimen. 



The trepang, or beche-de-mer , is extremely abundant throughout 

 the bay. In five minutes a small dredge brought up forty- 

 eight specimens of Holothuria marmorata at Station 12. This 

 species is the most abundant trepang. Most of the specimens 

 obtained were about 9 inches long and 4 inches broad. Other 

 species well represented are Holothuria atra and Holothuria scabra. 

 In September, 1911, I saw large numbers of Holothuria atra on the 

 eastern shore of the Ostenberg peninsula. Holothuria scabra is 

 interesting, because of its colour variaition in different parts of the 

 coast. In the Trincomalee and Galle specimens the dorsum is black, 

 with well-defined transverse yellow stripes, and the ventral surface 

 is yellow, with numerous gray mottlings. In the Jaffna specimens 

 the back is gray in colour, and the yellow stripes are generally absent. 

 The ventral surface is yellow, and does not possess the gray patches. 

 The Jaffna variety resembles very closely specimens which I have 

 examined from East Africa, and the "Challenger" specimens 

 described by Theel ; upon a superficial examination the two forms 

 appear to be distinct species. 



From time to time the trepang fishery at Trincomalee has 

 given rise to a minor industry of no mean importance. In 1902 

 Herdman witnessed trepang diving operations at Trincomalee. He 

 states that the divers obtained 75 cents per hundred for them. 

 During my January visit I made inquiries, and learned to my 

 surprise that the trepang fishery was no longer carried on. This 

 cannot be due to scarcity of material. 



The trepang at Trincomalee are obtained by diving in all 

 depths up to 8 fathoms. This method differs from that practised 

 at Jaffna, where the trepang {Holothuria scabra) occurs in the 

 shallow water, which for miles does not exceed a depth of 1 or 

 2 fathoms. There the bottom is clearly visible from the boat, 

 and when a trepang is seen, it is speared hj means of a two-pronged 

 fork attached to a long pole. This method cannot be practised 

 at Trincomalee owing to the greater depths, and hence diving is 

 resorted to. 



The Trincomalee divers are much more efficient than those 

 at Tamblegam. The latter do not care to dive at a greater depth 

 than 3 fathoms, and never stay under water more than 8 seconds 

 when working at a depth of 1 or 2 fathoms. The Trincomalee 

 divers work in couples as a safeguard against sharks, and they will 

 go to a depth of 8 fathoms without the aid of weights, which the 

 divers in the Gulf of Mannar alw^ays use. I have known them to 

 remain under water for a minute, although the average time is only 

 about half that. 



All my work at Trincomalee, with the exception of two shore 

 collecting trips, was conducted from an unseaworthy old pilot boat 



