1922] MADRAS PEARL FISHERIES 109 



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 

 rock 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 compo- 

 sition of the sand varies considerably; on the surface of the rock 

 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 Siphonochalina 

 communis, Spongionella nigra, Axinclla tubulata, Axinella donnani, 

 Clalhria indica. 



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

 Eunice tubifcx is abundant. 



Other common organisms are Pentaceros lincki, Linckia laevigata, 

 Antedon spp., Ophiuroids ; Scrupoccllaria sp ; Padina commersoni, 

 Codium tomentosum . 



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 pars in 1899 and 

 would have been ready to fish the following year when however 



