Shell oval, broader behind, much depressed, front slope convex, the other slopes convex above, but concave towards the margin, which is still more depressed. Colour white. Apex placed at about 7/11 of the total length, slightly curved, without distinct whorl. Sculpture consisting of about 56 radiating ribs, some of which are thinner; they are crossed by numerous, thin, rather close-set, concentric ridges, which are straight in the interstices, arched on the ribs, forming short scales, Slit-fasciole large, very deep, crossed by numerous, thin, arched lamellae, slit large, length about 2,75 mm, breadth 1 mm. Margin thick, crenulated by the ribs, its sides slightly raised. Interior smooth, white, bluish towards the centre; margins of the slit much thickened, with a very short rib, running in the direction of the apex. Long. 11 mm, lat. 8 mm. , alt. 3 mm. The animal is yellowish-white, it has rather long tentacles and about 12 epipodial filaments on each side.

Diagnosis: Oblong-ovate, markedly widest posteriorly, height/length 0,20-0,59; apex situated 0,39-0,44 distance from posterior end; anal slit rather wide, left anterior margin level with right side; bordering flanges low, crossed by growth plicules, lunulae 3-6 per mm; radial ribs low, flattened, 50-60, alternately weaker and stronger, concentric lirae finer, forming rather large, flattened scales; interstices with growth lines only; white, interior brownish; maximum length 18,7 mm.
Description: Outline oblong-ovate, anterior end markedly narrower than posterior end; very depressed, height/length 0,20-0,30, rarely as great as 0,59; apex only slightly recurved, situated 0,39-0,44 of distance from posterior end; posterior slope gently concave to flat, anterior slope convex to flat, lateral slopes concave to convex, profile generally flattening out slightly towards ventral margin; margin usually concave, sometimes convex with posterior end curved slightly upwards. Anal slit shallower and relatively wide, sometimes rather U-shaped, situated slightly off the midline; selenizone not sunken, forming a somewhat angular ridge internally; bordering flanges rather low and incised by oblique plicules; lunulae 3-6 per mm, not corresponding to concentric lirae; anterior margin on either side of slit level. Sculpture cancellate; radial ribs low, flattened and rather wide, about 50-60 in number, for the most part alternately weaker and stronger, with an occasional fine tertiary thread in the intervals; concentric lirae finer than radial ones, with relatively large, strongly arched, flattened scales where they cross the latter; interstices with rather coarse growth lines. Inner ventral margin incised into a series of concave-tipped denticles. Colour white, interior with a median blotch of yellowish-brown (bluish according to Schepman).
Dimensions: 11,0 x 8,0 x 3,0 mm, anal slit 2,8 mm deep (holotype); 17,1 x 12,2 x 3,6 mm, slit 2,8 mm; 15,2 x 10,1 x 3,0 mm, slit 3,2 mm; 18,7 x 11,8 x 11,0 mm, slit 3,8 mm (N.M. examples).
Radula: Very similar to that of Emarginula obovata A. Adams, 1851, as figured by Thiele (1929: fig. 17a).

Distribution: Indonesia to Mozambique and south to Palm Beach (30°59'S).

This species is allied to E. clypeus, but may be at once distinguished by the colour of the animal, the shell is less elongated than in E. clypeus, the apex is more elevated and recurved, the slit is larger and longer, the sculpture seems to be coarser. I have not seen a loose shell of E. clypeus.

Indonesia, Maluku. Salibabu Island. Off Lirung.