No. 6 (1921) COMMON MOLLUSCS OF SOUTH INDIA 



189 



majority of estuaries and backwaters in India, south of the Ganges 

 and Indus. At Tuticorin it is fairly abundant, as a woman can 

 easily collect from 30 to 40 in a tide. They are esteemed as food 

 by the Valaiyans and Pallans who collect them and who use the 

 empty shells for lime-burning. The flesh is considered less delicate 

 than that of the common clam; it also seems less hardy; as a 

 consequence its distribution is more local and restricted — it 





mm. 



Fig. 52. The (ireat Clam (A/er<;!rix meretrix). Two-colour varieties. Note the short 

 siphons and the great extensibility of the foot ; in the lower figure the dotted outline 

 indicates the extreme extension possible. (Tuticorin.) X §• 



appears to require a cleaner habitat than M. casta and a strong tidal 

 current over the bed where it lives. Hence they are usually found 

 near the entrance to lagoons, where the tidal flow is great. They 

 spawn about the beginning of September at Tuticorin, probably 

 also about May. 



The shell exhibits considerable variation in colouring, and at 

 least five well-defined colour varieties are known ; apart from the 

 umbonar region which is very frequently rayed, the shell usually 

 exhibits no banding, but in two varieties there are very broad ill- 

 defined radiating bands of a somewhat livid or purplish colour 

 extending from the ventral margin to half way to the umbo. The 

 . jmbo nearly always shows considerable colour, but this is extremely 

 •/ariable and no two shells are exactly alike in this respect. Most 



