NARRATIVE. 



37 



some rock in situ and large boulders. Rock oysters and a species of Area are 

 abundant on tbe rock and boulders (fig. 3) and on pieces of* wreck, also quantities oi 



Fig. 3. Rock oysters (Osbrea sp.) i;i Trincomalee harbour at low tide. 



Mytilus of good size were living on and in the gravel anchored by the byssus. 

 Attached to these and to other objects were many pearl oysters of smallish size. 

 Samples of these were taken alive to our laboratory on board ship. In the sand around 

 the island Pinna bicolor lives in abundance, of large size, almost wholly buried, the tips 

 of the valves just projecting beyond the level of the sand, and the byssus deep below, 

 generally having some larger objects such as small stones and dead shells attached to it. 

 On the shores of Powder Island we also found Periophthalmus kohlrcuteri and thick- 

 bodied land-crabs, and also a shore-crab with a long crenated front margin between 

 the eyes ; a Nentina and a Littorina were common, and we found a large rough 

 Nudibranch, yellow and grey speckled, under a stone. 



I obtained a native dug-out canoe and went across the bay towards Orr's Hill to 

 see some natives diving for trepang in a few fathoms of water. The species were 

 Holothuria marmorata (spotted yellow and brown forms) and H. atra (black, with 

 a lighter pinkish under-surface). The divers were said to obtain 75 cents (one shilling) 

 per 100 for these. 



We next examined a reef of rock and coral lying off the Cutcb Co.'s bungalow. 

 Here by wading, or by using the water-glass in the deeper parts, we saw living 

 coral in quantity (chiefly Porites and Astrseids), much sponge, and many fair-sized 

 pearl oysters attached either to mussels as before or to the rock by their byssus, 

 They appear to extend sporadically across the sand from Powder Island to Orr's Hill. 

 Pinna bicolor and P. fumata were present in the sand and gravel around, and an 

 Ostrea on the rocks. We caught a small yellow Ostro.cion amongst the pearl oysters. 

 Undoubtedly this spot, and the ground round Powder Island and the shoal at end 

 of Nicholson's Cove are the best spots in Trincomalee for the cultivation of the pearl 



