The Thai material consists of juvenile specimens and variously sized fragments of the spire. They are assigned to the present species on the basis of 1) protoconch low-conical, of 3 whorls, the last 2 distinctly shouldered, with 1 peripheral and 1 abapical fine thread, 2) great spiral angle, 3) sculpture of collabral ribs and overriding, uneven spiral grooves and 4) twin subsutural cord. DISTRIBUTION AND HABITAT. Nassarius obesus was hitherto known from the Persian Gulf to India and Malaysia. There is no information on its ecological requirements. FOSSIL RECORDS. None recorded.

Shell up to 22.0 mm in length but some specimens only half this size, globosely conical, solid, last whorl rotund, teleoconch of 5-6 whorls, protoconch of 3 glassy, carinate embryonic whorls, sculptured with thick axial ribs which number from 16-18 on the penultimate and from 18-21 on the body whorl, ribs occasionally obsolete on the dorsal side of body whorl but becoming more crowded towards outer lip; spiral sculpture consists of spiral grooves and threads, 2-3 cords anterior to suture of body whorl rugose, grooves becoming obsolete on centre of body whorl, base of shell with 7-10 cords. Aperture narrow, outer lip thick and with 6-7 strong denticles within, columellar callus spreading on to body whorl and frequently thinning above parietal wall, columella with 2-6 denticles, siphonal and anal canals distinct. Uniformly brown to tan in colour, some individuals minutely and indistinct- ly mottled with white, columellar callus and aperture white. TYPE LOCALITY, Kutch, India (obesus); Ceylon and Penang (ceylonica); Persian Gulf (eranea); Ceylon (shawi). DISTRIBUTION. From the Persian Gulf to India and Malaysia.