104 



on tills reef, whicli is surrounded by 4 5 to 5 fatlioms of 

 water, belong to the genera Madrepora and Pocillopora^ while 

 Galaxea and Leptoria are present in less abundance. The 

 bright white patches of sand, which cover large spaces 

 between the coral growths, teem with Protozoa and a 

 calcareous Alga, and are more rich in delicate molluscs than 

 any other deposit which I have examined in the Gulf of 

 Manaar. Sheltered among the coral tufts were sluggish 

 Holothunans and hosts of small Crustaceans ; and, clinging 

 to the branches of a Madrepore, I found a single specimen of 

 the quaint Themis orientalis. 



Outside the seaward face of the pearl banks on the Indian 

 coast of the Gulf of Manaar the depth of the sea increases 

 very gradually, so that, for example, outside the Tholayiram 

 Par, a depth of only l/> to 20 fathoms is reached at a 

 distance of 3 miles. Outside the Muttuwartu Par, how- 

 ever, the area of shallow water ceases very abruptly, and the 

 depth increases rapidly to 150 fathoms at a distance of three- 

 quarters of a mile from the seaward face of the bank, where 

 the following temperatures were recorded : — 



Several hauls of the dredge brought up Polytrema 

 cj/Iindricum, Gorgoniw, Heteropsammia coehlea, Cirrhipathes 

 spiralis, Spongodes sp,, Fibularia orulum, &c., but no pearl- 

 oysters. 



The divers received instructions to keep apart for me 

 everything, other than oysters, which they came across 

 during their day's work, under the general heading of corals, 

 shells, poocheps, and weeds; and, by examination of the 

 specimens which they reserved and going rapidly over the 

 oysters, I was enabled not only to make a rich collection 

 which awaits future investigation, but also to ascertain 

 roughly in what respects the faiina of this portion of the 

 West Coast of Ceylon differs from that of the Indian Coast 

 of the Gulf of Manaar. The first day's inspection of the 

 Muttuwartu Par showed not only that the oysters were very 

 abundant, in spite of the disturbance to which they were 

 subjected during the fishery in the spring, 4,580 living 

 specimens being brought up in 291 disres; but, further, that 

 the coral-incrusted shells, to which I have already referred 



