116 CEYLON PEARL OYSTER REPORT. 



living corals ( Turbinaria, Montipora), Sarcophytum, Socarnes sehmardcs, Tridacna sp., 

 and Area sp. 



This paar yielded important fisheries in 1889, 1890, and 1891, the last being one oi 

 the most valuable fisheries that has ever been held, over 44 million oysters being 

 fished at a return to Government of over 963,000 rupees. The bank had never been 

 recorded as fished before 1889, and it is said that it was unknown to the Dutch in 

 1757, although we believe we have evidence that it was the source of fisheries in 

 earlier Portuguese times. Captain Donnan says that a bed of oysters died on this 

 paar unfished in 1860 ; another bed disappeared in 1899. 



To the north and east of the paar proper, in 7 to 8 fathoms, we found a hard and 

 in some places rough bottom with plenty of " rock " and other hard fragments 

 which would serve as " culch " for oysters. In places there are large branching 

 Madrepores and great vase-like elephants-ear corals (Turbinaria) ; also Phyllo- 

 spongia holdsworthi and other sponges. While the greater part of the ground, like 

 the Cheval, the Modragams and the Periya Paar could be readily worked with 

 the dredge, there are certain parts of this paar and the neighbouring ground which 

 are unsuitable for dredging, and would, if that method of obtaining the pearl oysters 

 were adopted to the exclusion of diving, form valuable preserves where the necessary 

 stock of breeding oysters might remain undisturbed. 



There is a diseased condition that the Muttuvaratu pearl oysters seem liable to, in 

 which the body is stunted and shrunken, and the mantle and other tissues become of 

 a markedly opaque yellow colour. This yellow condition has been noticed in the past 

 by Sir W. Twynam and by Captain Donnan. We found some affected specimens 

 during our first cruise in the "Lady Havelock" in February, 1902, and others on 

 every occasion when the bank has been visited since. On 14th April, 1903, out of 

 227 oysters examined, 25 were affected with the yellow disease, over 11 per cent. 

 This condition, which seems to cause considerable mortality amongst adult oysters, 

 will be discussed in the account of our laboratory work later on in the Report. 



Hamilton's Muttuvaratu Paar. 



This bank lies 2 miles south-east of Hamilton's Alantura Paar and 2^ miles oft 

 Karativo Island. It is 1 mile in diameter, and the depth is from 4^ to 6^ fathoms. 

 The bottom is irregular, partly rock and partly sand. 



There were no oysters, and this paar is unimportant. 



MUDALAIKULI PAAR. 



This lies 3 to 4 miles south of Muttuvaratu Paar and 1 to 2 miles off Mutwal 

 Island. It consists of two areas, an outer rocky part 1^ mile in diameter and 4 J to 

 8 fathoms in depth, and an inner more sandy part 1 mile in diameter and from 2| to 

 5 fathoms in depth. 



