I88 MADRAS FISHERIES BULLETIN VOL. XIV, 



Pariahs and Pallans and some of the Muhammadans and 

 Christians of coast hamlets are the only people who eat these 

 clams in Tamil districts. 



On the East Coast, spawning appears to take place twice in 

 each year, the first during April and May, the second about Sep- 

 tember. The busiest fishing season at Pulicat and the neigh- 

 bourhood is the hot dry season from June to August when the 

 level of the backwaters and canals becomes much reduced, facili- 

 tating greatly the work of collection. At this season the condition 

 of these clams is at its best, the bodies fat and swollen with 

 reproductive products. 



At Pulicat, Sonapur (in Ganjam) and Tuticorin great beds of 

 subfossil shells occur in silted up portions of the local backwaters 

 and the bulk of the shells forming these beds are of this species. 

 At Tuticorin and Sonapur a curious variety is also common, distin- 

 guished by an extreme thickening of the hinge plate and umbonar 

 region. This causes each umbo to become unusually prominent 

 and distinctly hooded. The general form of the shell is affected, 

 becoming so trigonal that it has been described as a distinct 

 species. But all gradations between this form and the typical 

 M. casta can be traced ; so it is at most a variety. 



The Great Clam, Meretrix meretrix, called in Tamil paiija- 

 matti {u(^^LDi-isf-) at Tuticorin, is a nearly related species to the 

 common matti (M. casta). It is distinguished by its greater size 

 and by the smoothness and delicacy of the periostracum covering 

 the valves. Its average dimensions when adult range between 

 74 X 60 mm. and 75 x 62'5 mm. with a weight (empty) of about 

 3^ ounces. The valves are perfectly smooth and so long as the 

 periostracum is intact have a beautifully polished appearance due 

 to the smoothness of, this membrane, which is thin, delicate, and of 

 a pale straw colour in tint. When this is removed the shell is dead 

 white in colour except along the postero-dorsal margin where there 

 is a deep band of greyish blue in some and bluish brown in others ; 

 this colouring occupies precisely the same region as in the common 

 clam {M. casta). It is a very beautiful shell and the pity is that it 

 is not more abundant. I have found it in the Silavathurai fish farm 

 at Tuticorin, in the seaward part of Pulicat Lake, and in a sub- 

 fossil condition at Surla in Ganjam district. It lives also in Chilka 

 Lake, and is known also from Tellicherry and Bombay on the West 

 Coast. There is little doubt that it lives at the mouths of the 



