Crepidula walshi is characterized by 1) irregularly subrectangular rather flattened shell, wider than long, attaining 30 mm in size, 2) apex small, at or close to the posterior margin, 3) internal septum shelf-like, slightly convex, attached just inside the posterior margin and 4) outer surface with fine growth markings. Crepidula walshi is unlike any other Crepidula species described in the literature.

DISTRIBUTION AND HABITAT. The species ranges from the Persian Gulf to the Arafura Sea and northward to Japan. Crepidula walshi is a filter feeder (HOAGLAND, 1977) usually found attached to Pinna and Mytiius spp. (SPRINGSTEEN & LEOBRERA, 1986) or to dead shells (KIRA, 1965); in Hong Kong it is commensal with hermit crabs, being attached to the inner surface of the outer lip of the host shell (YIPP, 1985; BOSCH et al., 1995). The species occurs intertidally (WAY & PURCHON, 1981) and subtidally down to about 40 m (HAYASAKA, 1961); it was noted to live on Pinna hicolor at a depth of 8 m in western Thai waters (TANTANASIRIWONG, 1978).