Holocene and recent shallow soft-bottom mollusks from the Northern Gulf of Thailand area: Scaphopoda, Gastropoda, addition to Bivalvia

The scaphopods, gastropods and some newly found bivalves recovered from the Holocene Bangkok Clay in the Lower Central Plain of Bangkok along with those obtained from modern shallow bottoms in the Phetchaburi coastal area are recorded and described. The gastropod assemblages of the Holocene Bangkok Clay appear to parallel the Recent ones recovered at sea from intertidal and shallow infralittoral, predominantly muddy substrates. Rissoidea, Muricoidea, Conoidea and Pyramidelloidea are the most diverse groups, with species that often occur abundantly. This paper covers 336 species, of which 23 are proposed as new; 108 remain unidentified and are, at least partly, previously undescribed. The species treated are complemented with taxonomic remarks when necessary and with information on respective ecological requirements if available. Nearly all species are illustrated in the plates. A list of references to the mollusk fauna of the Indo-Pacific Region is also given.