TYPE SPECIES. — Depressipoma laddi n. sp.

DIAGNOSIS. — Profile low with strong peripheral angulation midway on whorl, maximum diameter 3.3 mm; whorls rounded above and below peripheral carination, shoulder and base with narrow spiral cords, axial sculpture of narrow, projecting ribs; umbilical area broad, with deposition of callus to strengthen shell; final lip broad and projecting, composed of successive layers of fine lamellae; base of lip with short triangular tongue.

DISTRIBUTION. — Marshall Islands, Micronesia, west of the international date line and just north of the Equator.

REMARKS

Two species resemble Liotipoma in sculpture, have a similar aperture and lip with the projecting tongue, but have such a low profile that there would be no possibility to form a brood chamber within the umbilical cavity.The specimen of D.laddi n. sp. shows a lumpy deposition of callus across the umbilical area, which serves to strengthen the shell in the position at which its weak early stage would need fortification. The specimen of D. kwajaleina n. sp. is in poor condition with agglutinated sand obscuring what is probably the same feature in the umbilical cavity.