I48 MADRAS FISHERIES BULLETIN [VOL. XVI, 



Those parts of this region which came under my personal notice 

 bore but small quantities of loose stony material, " cultch " as it is 

 technically termed, a decidedly unfavourable factor, as the oysters 

 need such material for the purpose of attachment. Attention 

 should in future be given to this detail during inspection, in order 

 to ascertain if this difficiency is, as I think it is, general over the 

 whole area. In the event of this proving to be case means should 

 be taken to increase the available quantity whenever an extensive 

 spat-fall is found to have occurred. 



{d) Pearl Production— Causes of Death. 



Pearl production by the oysters fished in 1889 on the Tolayiram 

 Par, the only bank regarding which I have any data, was less rapid 

 than that noted during the past two years on the Ceylon Cheval 

 Par. On some sections of the latter, satisfactory pearl production 

 is found at the age of four years, valued at over Rs. 21 per 1,000 in 

 the case of those fished in IQ03, whereas the last oysters fished on 

 the Tolayiram Par were at a similar age valued at but Rs. 3 -1 1-5 

 per 1,000. It was not till they attained the age of 5% years that they 

 brought in an equivalent value (Rs. 22-8 6 being the actual average 

 price per 1,000 at the 1889 fishery) to that of Ceylon oysters \Y 2 year 

 younger. The latter, however, were those from the richest known 

 beds and there were others which at the same age — 3% to 4 years — 

 were not rich enough in pearls to give a profitable fishery. Pearl 

 production is, however, very variable and the yield by one genera- 

 tion is not necessarily a criterion as to what the next may furnish, 

 even upon the same ground. 



Examination and comparison of the Tolayiram Par oysters of 

 1887-90 with those of Ceylcn give fairly satisfactory results in 

 respect to shell growth. They are not equal to the finely grown 

 oysters of the Cheval, but in general appearance are of a healthy 

 type. They are nowise stunted-looking as so many of the oysters 

 on the Pars more inshore are, or, as are the oysters characteristic 

 of the Ceylon Muttuvaratu Par. But although they are distinctly 

 of the Cheval Par type, they are of slower growth and the weight 

 of the shells approximated closely to that of Muttuvaratu oysters. 

 Given an abundant infection of pearl-inducing cestode parasites, 

 the pearl production should be profitable in quality and quantity. 

 This question is still one on which we are imperfectly informed ; 

 the life-history of the parasite is still unsolved, and till we know 



