1922] MADRAS PEARL FISHERIES 95 



oysters noted in i860 as 3H years old were in all probability there 

 in 1861 , in the spring of which no examination was made, the 

 officers in charge being busy with the fishing of oysters of a 

 similar age on the inshore pars. This divergence in results is due 

 in great part to the Ceylon bank being situated in a relatively 

 more exposed position being close to the edge of the precipitous sub- 

 marine cliff that margins the seaward aspect of the Ceylon Pearl 

 Bank plateau. As a consequence the heavy seas which characterize 

 the period of the south-west monsoon break in unmitigated violence 

 upon the Periya Par, whereas on the Indian coast the movement of 

 the water during the same season has undergone considerable 

 amelioration when it reaches the Tolayiram Par from travelling 

 over a couple of hundred miles of comparatively shallow water. 



Faunistic and many physical (chiefly geological) characteristics 

 link the Tolayiram with the Periya Par ; but in regard to the aspect 

 and degree in which the former meets the fury of the south-west 

 monsoon, its position is more comparable with that of the Cheval 

 Par which lies on the leeward side of the Periya Par, and is as 

 consistently reliable as the latter is the converse. 



The value of the Tolayiram Par may be assessed as midway 

 between the Cheval Par and the Periya Par, inferior to the former 

 chiefly by reason of oyster spat being less abundant and to current 

 conditions (surface-drift) being less favourable to the deposit of 

 such spat on the Indian than the Ceylon side; — partly also to the 

 conditions of life being somewhat less favourable on the Tolayiram 

 Par owing to the greater amount of sediment present in the sea on 

 the Indian side. 



The data for the institution of comparison between the rate of 

 growth normally characteristic of the Tolayiram Par oysters with 

 that of oysters from typical localities on the Ceylon side rest upon 

 a single series of measurements and weights of that generation of 

 the former that survived to a fishable age in 1889. The resultant 

 comparisons based upon these dimensions are highly instructive 

 and while in my opinion I believe it is probable that they are quite 

 typical of the normal progress of growth of oysters on this par, 

 further series of growth observations are desirable and inspectors 

 after this should be instructed to record the necessary particulars 

 on every available opportunity. 



Two methods of comparison are available : (a) the external 

 dimensions of the oysters when alive, and (b) the weight of the 

 cleaned shells. 



