Shell sculpture, external morphology of the body and pallial organs, digestive system, reproductive organs and types of sperms of three species of potamidids, Cerithidea (Cerithideopsilla) cingulata, C. (Cerithidea) obtusa and Telescopium telescopium collected from Veliar-Coleroon estuarine complex are studied, described, illustrated and discussed in this account.

Electrophoretic analyses showed that the pattern of protein fractions indicated closer association between C. (C) cingulata and C. (C) obtusa at interspecific level and both differ from T. telescopium. Of the three species, C. (C.) obtusa appears to be more advanced and evolving gradually towards terrestrial mode of life.