Invertebrate Gallery of the Indian Museum. 1 1 7 



The members of this family are almost entirely inhabit- 

 ants of the tropics : most of them are marine and littoral, 

 but some [Neritella, Navicella) occur in rivers, and some 

 are amphibious in certain estuarine localities. They are 

 all herbivorous. Specimens of all the known genera are 

 to be found in Cases 133 A — 134 A. The shells are cap-like, 

 the last whorl being large, and the preceding whorls 

 being small and often more or less absorbed. The oper- 

 culum is either horny or may be a thin calcareous plate. 



3rd Family, Pieurotomaridse [Case 134A]. 



A small family of herbivorous gastropods found for the 

 most part among the coral-reefs of the Indo-Pacific. The 

 shells of Stomatia have a resemblance to those of Haliotis. 



4th Family, ScalaridsB [Case 134B-C]. 



The members of this small family are predaceous, and 

 though widely distributed occur in greatest abundance in 

 Eastern Seas. The shell, which is closed by a horny oper- 

 culum, forms a most elegant tapering spiral, the whorls of 

 which are ornamented by numerous equidistant cross-ribs. 

 Scalaria secretes a purple fluid when molested. 



5th Family, JanthJnldge [Case 135A]. 



The Janthinidse or " Violet Snails" are predaceous 

 mollusks which live at the surface of the open oceam 

 being kept afloat, as by a buoy, by a long cluster of air- 

 vesicles developed on the " foot." The shells are commonly 

 cast ashore on the coasts of India after strong southerly 

 gales. Janthina is able to secrete a purple fluid, by which 

 the thin shell is beautifully dyed. Observe the spirit 

 specimen of a female Janthina above Case 135, showing 

 the vesicular float-like foot, with the egg-capsules sus- 

 pended from its under surface. 



6th Family, Cerithldse [Cases 135B— 136C], 



Of the species of this large family some are marine, 

 some, as Pyrazus and Telescopimn, inhabit mangrove 

 swamps and brackish marshes, and a few [Cerithidea) 

 are amphibious. Some species of Cerithiuniy secrete a 

 green fluid when molested. The shells have the form 



