344 



Memoirs of the Indian Museum. 



[VOL. V, 



living individuals were dredged in the middle of the southern part of the lake, per- 

 haps making their way from one set of rocks to another. 



T. carinifera is the only Gastropod obtained in the main area whose shell is of 



any considerable size ; the range of 

 the hermit-crabs of the genus Cliba- 

 narius is therefore co-terminous so 

 far as the main area is concerned 

 with that of Thais. The boring 

 sponge Cliona vastifica sometimes at- 

 tacks living shells and the Polyzoa 

 Alcyonidium my tili and Membrani- 

 pora hippopus are sometimes found 

 on its surface. 



Eggs, of which we figure a cluster, 



were observed on the rocks at Ganta 



Sila in February and on oyster-shells 



at Manikpatna in March. They were of a dirty yellowish colour when living, but 



their contents became deep purple when they were placed in alcohol. 



Fig. 2.— Thais carinifera (Lam.). 



A cluster of egg-capsules ( x 2|), with a single capsule 

 more highly magnified. 



Family Cerithiidae. 



Potamides (Tympanotonos) fluviatilis, Pot. and Mich., Gal. de Moll., p. 363, pi. 

 xxxi, figs. 19, 20; 1838 (as Cerithium). 



P. fluviatilis occurs in great abundance along the outer shore of the main area, 

 at Nalbano and in the outer channel. A few specimens were also seen in a small 

 ditch opening into Rambha Bay ; but the species is very scarce along the inner shore 

 of the main area. It seems to prefer a bottom of sand or sandy mud and to be able 

 to endure temperatures that are fatal to most other species ; it occurred in enormous 

 numbers near the mouth of the outer channel in the freshwater season. Its shell 

 is very commonly occupied by the hermit-crab Diogenes avarus and living individuals 

 were occasionally found to which young oysters (Ostrea sp.) or small examples of a 

 barnacle {Balanus amphitrite) were attached. The hydroid Clavactinia gallensis was 

 found on several shells occupied by hermit-crabs, while others, still occupied by their 

 proper owners, were covered by the Polyzoon Alcyonidium mytili. 



The species is widely distributed in the Indian Ocean and the western parts of 

 the Pacific, occurring usually in brackish water; but according to Mr. Townsend is 

 a distinctly marine form in the Persian Gulf. 1 It was described from the Malabar 

 Coast. 



Potamides (Telescopium) fuscum, Schum., Reeve, Conch. Icon., XV, fig. 1 (1866). 

 Living specimens were common on some of the islands in the outer channel in 

 March. They appeared to be comatose and many of them were half buried in 



See Melvill and Standen, Proc. Zool. Soc. London, 1901, p. 375. 



