108 MADRAS FISHERIES BULLETIN [VOL. XVI, 



In its fauna, physical structure, and history, it is in close 

 agreement with the inner Kudamuttu region, and was fished in 

 conjunction with the Kudamuttu Pars in 1828. Spat-falls have 

 several times been recorded since 1861, namely in 1878, 188 1, 1895 

 and 1897 when young oysters lay thick on all the rocky outcrops 

 and wherever there was any cultch, quantities being found adher- 

 ing even to the valves of Pinna, which are fairly abundant on the 

 edge of the sandy ground on the western margin. 



The generation of oysters seen for the first time in 1897 were 

 reported healthy and still plentiful in the following year, but in 

 1899 the bank was described as almost bare of oysters. A very 

 large number of byssal cables was noticed at this 1899 inspection, 

 indicating probably a recent inroad by rays (Rhinoptcra sp.) upon 

 what must have been a promising bed of oysters. 



The Inspector, I observe, remarks that the presence of these 

 byssal strands "shows plainly that the oysters of last year have 

 migrated," a deduction not warranted by an intimate knowledge 

 of the habits of the pearl oyster. 



Whenever an occurrence of this nature be met with, care 

 should be taken to ascertain the condition of the individual byssal 

 cable; we require to know whether the majority show signs of 

 having been broken with violence as happens normally when 

 oysters are torn away from their attachment, or if the strands 

 of each cable join together at the free end in a pale coloured 

 semi-gelatinous "root." Only if such " roots " be present can we 

 infer voluntary migration, for when an oyster decides to shift its 

 quarters it sloughs the root of the byssus ; it never severs it — 

 indeed such is an impossibility. In any case a pearl oyster's 

 migration is hardly worthy of such a designation ; at the most its 

 journey can be measured in yards and for practical purposes the 

 power may be ignored — a power of little advantage to the 

 possessor except to shift position from one side of a fragment of 

 rock to another. Thus I have seen an oyster three years old crawl 

 our inches up the side of a stone to get away from an eddy of 

 sand playing round the base. 



11. Karuwal Group. 



A series of the usual small rocky patches called pars lying 

 seven miles east-north-east from Trichendur Pagoda. The depth 

 is 7 l A to 8 fathoms. 



