422 The Tinnevelly Pearl Banks. 



but in 1863 tlie banks were found to be in a most unpromising- 

 state, and no fishery was attempted. Out of seventy-two 

 banks that were examined, only four contained oysters free from 

 soorum, eleven had young oysters mixed with soorum, and 

 fifty-seven were blank. It is this unexpected failure of 

 properly-grown shells which has given rise to Captain Phipps' 

 experimental culture now in course of trial, and to a very 

 careful consideration of the conditions most likely to secure a 

 good annual fishery, which shall not be liable to this periodical 

 sterility. 



The pearl banks are about nine miles from the shore, and 

 8 to 10 fathoms from the surface, being scattered over an area 

 70 miles in length. They are exposed to ocean currents, 

 which, by washing sand into the interstices of the rocks, 

 often destroy the young oysters over a considerable area; 

 the dead fish, when not removed, soon contaminate their 

 neighbours • and, in addition to these sources of evil, the soorum 

 shells, a species of Modiola, like a mussel with a swollen face, 

 which often grow amongst the pearl oysters, exercise a per- 

 nicious influence, either by dying and spreading death around 

 them, or by accumulating sand. It is obviously quite impos- 

 sible to watch these banks efficiently, and to eradicate the 

 evils caused by sand accumulations and dead molluscs, owing to 

 their great depth and exposed situation in the open sea at a 

 distance from land. Unless some plan is adopted for rearing- 

 the young fish on banks which shall be constantly accessible, 

 and free from the above drawbacks, the fishery will always be 

 liable to failures, sometimes of long duration. The perfection 

 to which science and intelligent care have brought the fisheries 

 of edible oysters on the English, and especially on the French 

 coasts, leaves no doubt that equally satisfactory results might 

 be obtained from similar measures on the Tinnevelly pearl 

 banks. 



A few remarks on the habits of the pearl oyster will make 

 this part of the subject more clear. 



It is, perhaps, unnecessary to observe that the pearl oyster 

 (Moleagrina margaritifera, Lam.) is not in reality an oyster at 

 all, but is more allied to a mussel; having, like the latter 

 animal, a byssus, or cable, by which it secures itself to the 

 rocks — one of the most important points in its organization. 

 The animal's foot is composed of musdular fibres, and is 2\ 

 inches long, when distended. On the lower side there is a 

 groove lined by a secreting membrane, which is an exact 

 mould for the formation of the Jnjssus. When the animal 

 desires to attach itself to the rock, its foot is protruded, and, 

 after sec-king out a suitable spot with the tip for some minutes, 

 is again retracted into the shell. A strong fibre, of the form 



