60 



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 four inches up the side of a stone 

 to get away from an eddy of sand playing round the base. 



11. Kakuwal Gkoup. 



A series of the usual small rocky patches called pars lying seven miles east-north- 

 east from Tiruchendur Pagoda. The depth is 7^ to 8 fathoms. 



The principal banks are Velangu Karuwal and the Karai Karuwal occupying the 

 southern portion of the group, with the Periya Malai Piditta and Naduvu Malai 

 Piditta Pars on the north, the whole scattered over an area about three miles long by 

 from one to two miles broad in an east to west direction. 



The rocky areas have the same general features as the other pars of the Central 

 division lying in a similar depth — flat-surfaced roek outcropping in patches of 

 different size from a surrounding waste of sand. 



The rock is the usual somewhat variable calcareous calcrete. The sand to the 

 west of the group is fine grained and passes gradually into a chank bed. On the par 

 region proper the composition of the sand varies considerably ; on the surface of the 

 lock foraminifera (Orbitolites and allied forms) form a notable proportion of the bulk ; 

 elsewhere the grain becomes frequently coarse and occasionally grades into a distinct 

 gravel. On the northern section a considerable amount of small Lithothamnion balls 

 is locally abundant. 



Among the characteristic organisms we have Siphonchalina communis, Spongio- 

 nella nigra, Axinella tubulata, Axinella donnani, Clathria indica. 



A few corals, chiefly Favia sp. (no Madrepores were seen) ; eunice iulifex is 

 abundant. 



Other common organisms are Pentaceros lincki, Linckia laevigata, Antedon spp. 

 Ophuiroids ; Scrupocellaria sp ; Padina commersoni, Codium tomenioaum. 



A considerable number of dead oyster shells were found of a size of those from two 

 and a half to three years old. Living oysters of about the same age were present here 

 and there, the majority enveloped in the encrusting mass of Clathria indica. 



The Karuwal group has brought oysters to maturity more frequently than any 

 other bank save the Tolayiram Par during the last century — in 1805, 1815 and 1862. 

 Since the last named date young oysters have appeared here in quantity at least five 

 times, — in 1863, 1874, 1878, 1884 and 1897; no inspection of the Karai Karuwal was 

 made in 1865, 1870,1873, 1874,1875, 1877, 1887, 1889-1890, 1892-1893, 1900 and 

 1902. 



The oysters found in 1897 were still on the pdrs in 1S99 and would have been 

 ready to fish the following year when however the bank was not examined, 

 owing presumably to the fishery then in progress on the neighbouring Teradi Puli 

 Piditta Par. 



The fishery of 1802 on these banks produced a net profit to Government of 

 Ks. 1,10,619. 



The general characteristics of the Karuwal group are the most favourable of any 

 seen during the investigation, the ground approximating most nearly to the condition 

 found on certain of the better parts of the Cheval Par— the most valuable and 

 reliable of all the Ceylou banks. 



In both cases we find the depth of water about the same, while the bottom on 

 the Karuwal group has a diversity in physical characters somewhat approaching that 

 found on the Cheval, stretches of rock much broken up by patches of sand overlaid 

 in places with a considerable quantity of eultch consisting of loose blocks of calcrete, 



