90 MADRAS FISHERIES BULLETIN [VOL. XVI, 



topographical, physical and biological — and therefrom by compa- 

 rison with one another and with typical banks on the Ceylon side 

 to evolve a knowledge of their relative economic importance in 

 regard to the prospect they respectively hold out of successfully 

 maturing such oyster spat as may from time to time settle thereon. 

 Such a comparative survey will also go some distance towards 

 enabling us to say what direction any measures of cultivation 

 should take, if it be found advisable or possible to assist nature by 

 artificial means. 



The configuration of the Indian coast of the Gulf of Mannar is 

 simpler than that on the Ceylon side. On the former there is no 

 great shoal like that of the Ceylon Karativu, which stretches north- 

 wards into the sea for a distance of nine miles giving a certain 

 amount of shelter to a great area of varied bottom, rock and sand, 

 lying in the Bay of Kondachchi. On the contrary the Indian pearl 

 banks lie open to the full force of the south-west monsoon which 

 on this coast sweeps up in great violence from south to north. 

 Again lying as they do on the west side of the Gulf, they also 

 experience much rough weather during the north-east monsoon, a 

 time when the Ceylon banks, lying under the lee of the land, enjoy 

 comparative quietude. The period of immunity from storm distur- 

 bance on the Indian coast is accordingly greatly curtailed and is 

 restricted under normal conditions to the months of February, 

 March and April. Occasionally fairly quiet conditions prevail 

 during the greater part of May— the onset of the south-west mon- 

 soon in full force being experienced somewhat more tardily there 

 than on the Ceylon side. 



This geographical disability of the Indian banks is linked with 

 and intensified by the mechanical disadvantage entailed by the 

 inferior character of the sand on that side, its finer grain and the 

 admixture with it of mud — characteristics which contribute to 

 increase greatly the turbidity of the water whenever heavy seas 

 sweep the pearl bank region. As already noted, these are condi- 

 tions which have probably become intensified concurrently with 

 the erosion of the southern extremity of India and which tend, 

 though with extreme slowness, in the historic sense, to reduce the 

 pearl oyster productiveness of this locality —deductions from which 

 we infer greater prosperity in times past. That there was such 

 anterior prosperity we have indications in the existence of remains 

 of ancient oyster-shell heaps close to Cape Comorin, in the frequent 



