150 MADRAS FISHERIES BULLETIN [VOL. XVI, 



I have had no opportunity to inspect a series of successive 

 generations of oysters from any other Indian Par. The individuals 

 seen from the Devi, Cruxian, and other inshore Pars appear much 

 inferior to those from the Tolayiram Par. They are small for their 

 reputed age, stunted in growth, and much encrusted with sponges, 

 corals and polyzoa. In general appearance they approximate to 

 those Ceylon oysters that hail from rocky beds — from the Muttu- 

 varatu Par and the Mid-west and North-west Cheval. 



The Tolayiram Par is the bank by far best suited to rear 

 healthy oysters in quantity. Unfortunately some of the characters 

 which render it so suitable for this, expose the oysters to heavy 

 risks from the depredations of fishes. The bare level bottom, free 

 from clefts and crannies and boulders, gives the rock-perch and 

 trigger fish {Vellamin and Kilati) every facility to devour enormous 

 quantities of oysters during the first year of their existence. The 

 bank swarmed with these fishes in May last and the question of 

 the possibility of the present young oyster population coming to 

 maturity depends largely on whether there be many more oysters 

 present than can be consumed by these fishes in nine months or a 

 year. When about one year old the shells become stout enough to 

 resist the sharp teeth of these fishes and the survivors have a fair 

 chance of living the allotted span of oyster existence, if the bank 

 be not harried by a shoal of oyster-eating rays {Rhinoptera spp.). 

 These fishes, the principal enemies of the adult oyster, are often of 

 large size, five feet or more across the disc and with mouth armed 

 with milling teeth of great crushing power. They are able to feed 

 only upon comparatively level ground and unfortunately the 

 Tolayiram Par is of this character. On the Ceylon side, I once 

 walked over an oyster bed ravaged at the most but a few days 

 previously. The sight was one never to be forgotten ; everywhere 

 the flat rock surfaces, originally densely packed with oysters, as 

 evidenced by occasional clumps remaining, and by multitudes of 

 torn byssal cables adhering still to the denuded surfaces, were 

 stripped in large part. Wide lanes had been ploughed through, 

 every oyster gone within the breadth of the lane. At frequent 

 intervals lay piles of broken shells, crushed fiat as if passed 

 through a mill. 



It is a significant fact that this ground is particularly " clean," 

 free from cultch and from any impediment to an animal scraping 

 the oysters off in wholesale quantities. It is ideal dredging 



