Shell small, reaching 7 mm. in length of shell, height being about 60 to 65% of the length; ashy white, maculated with four square blackish patches, one in front of the apex and one below the summit, the other two on both side slopes, but sometimes lacking partly or all of them; apical whorl smooth and polished, bent a little below the summit and reduced to a small hook, situated at the posterior end; anterior slope strongly convex and posterior slope straight; anal fasciole narrow and with numerous arched transverse lamellae; fissure also narrow and rather short, one-fifth of the length of the anterior slope; sculpture consists of about 30 primary ribs radiating from the apex to the margin, secondary ribs alternate with them; the distantly placed concentric cords cross the surface of the shell, forming nodules where they intersect the ribs dividing the spaces between the ribs into square pits; in addition to them numerous densely set concentric threads cover all over the surface of the shell, forming the delicate texture; margin crenulated. Height 4.3 mm., length of aperture 7.1 mm., breadth of aperture. 4.8 mm. (the largest paratype specimen collected by Mr. Akibumi TERAMACHI from Ryukyu group). Height 2.8 mm. to 3.5 mm, other specimen.

This species is very peculiar in the coloration of the shell and differs distinctly from any other species.

Japan: Okinawa, Ryukyu group.
This Japanese species, described by Habe is now known from between 10 and 20 Philippine specimens. It has been collected on the following Islands: Sumilon Island, Balicasag Island, Mactan Island, Siquijor Island, the Quatro Islands and Aliguay Island. Between 3 and 220 m deep. In the literature, we see Japanese material of 6 mm. In the Phililippines, between 3.5 and 4.9 mm. The combination of pattern and shape of the shell make this Emarginula an easy to identify species.