No. 6 (1921) COMMON MOLLUSCS OF SOUTH INDIA 



III 



accomplish. In the Philippine Islands the flesh of the Horn-shells 

 is esteemed as food ; the shells are thrown on wood fires and when 

 sufficiently cooked, the apex of the spire is broken off and the 

 animal sucked out through the broken end. Even the small species 

 of Cerithium are used in these islands as food. A third but smaller 

 species of Potamides (P. //m'/V/Z/Y/^) is common in brackish water 



Fig. 5. Horn-shells. 



A. Potamidcs cingjilatus. X 



B. Potamidis palustrh. X 



C. Pot am ides fuscum. X 



U 



it closely resembles Cerithium in the ornamentation of the shell. 

 In India, under purely fresh-water conditions, the Horn-shells are 

 replaced by the little Melanin, a tuberculated shell much like Ceri- 

 thium, but without the deeply channelled aperture characteristic of 

 the latter. 



Peculiarly aberrant in habit are the WORM-SHELLS (F^rw^//rf<2^), 

 for in adult life they are found always attached to rocks or embedded 

 in sponges. In early life they are free and their shells are regularly 

 spiral, but after they settle down, the spiral as it grows becomes 

 lax and distorted, and may readily be mistaken by the tyro for 

 that of Serpnla, one of the marine tube-building worms. Under 



