Of the 586 families of Mollusca currently described worldwide, 279 are represented in the Indian region, including 3628 species, of which 2300 are marine, 1129 terrestrial, and 199 freshwater species.

As there has so far been no proper estimation of the number of Indian species, the author initiated the assessment of molluscan diversity in India, and published a checklist of land molluscs, a handbook on freshwater molluscs and a catalogue of marine molluscs part I (including the classes Cephalopoda, Bivalvia and Scaphopoda) with other malacologists of the Zoological Survey of India. This work presents the remaining part of the marine molluscs (Classes Polyplacophora and Gastropoda), so as to get a comprehensive picture of molluscan diversity of India. This work is based on the earlier literature records on Indian marine molluscs, materials present in the National Collection of the Zoological Survey of India and the materials received by the Mollusca Section of the Zoological Survey of India from different sources for identification. Classification is according to Vaught (1989). Arrangement of the genera is made by the author as follows, i.e. the type genus first and then other genera arranged alphabetically, while the species arrangement is made alphabetically. For each species the synonyms are given beginning with the first synonym, followed by all available Indian references along with distributions (India and elsewhere) and remarks.