Shell height moderate; anterior slope broadly convex; apical whorl overhanging posterior slope; posterior slope concave; protoconch with linear and concentric sculpture; foramen represented by deep anterior slit, its position in earlier growth stages marked by a long selenizone. Sculpture radial and concentric; radial sculpture marked by primary and secondary ribs.
Mantle skirt slit corresponding to shell slit; epipodial tentacles of similar size, numerous. Ctenidia bipectinate, gill axis free.
Rachidian tooth broad, inner lateral teeth narrow; pluricuspid tooth massive, with inner and outer secondary cusps.

Shell more or less high cap- or cone-shaped; apex turned backward, sometimes closer to the center, sometimes closer to the posterior margin or even surpassing it; aperture shorter or elongated oval, along the anterior margin with a slit, from which a distinct slit band runs to the apex; surface with finer or coarser lattice-like sculpture, in most cases colorless. Central plate of the radula in most cases fairly broad, with cutting edge hardly bent over, smooth or finely denticulate; outer intermediate plate large, with strong, pointed main cusp and a smaller outer cusp; innermost lateral plate without cutting edge .
Subgenus Emarginula s .s. Shell not covered by mantle, with distinct slit and slit band; only a small group of species is colored. About 80 living species in the warmer seas.
* Section Emarginula s. s. Shell with more or less elevated apex, without internal septum. E. (E.)fissura (Linne).
* Section Subzeidora Iredale, 1924. Apex very depressed and close to the posterior margin, from which it is separated by a septum-like infolding.

South African Species !!!
Type species (monotypy) Emarginula conica Lamarck, 1801.
The southern African members of this genus show variable interstitial patterns and intntacalx pitting. They can be divided into four groups as follows:
1. Sculpture not cancellate, pits concentrically elongate, arranged in radial rows; e.g. E. undulata.
2. Sculpture coarsely or finely cancellate, interstices simple, i.e. with one pit or a pair of pits per interstice. This is the most common pattern, occurring in E. natalensisy E. agulhasensis, E. connelli, E. oppressa, E. viridicana, E. macclurgi and possibly E. phrygium.
3. Sculpture coarsely cancellate, interstices multiple, i.e. with more than one pair of pits per interstice, arranged like the dots on a die; e.g. E. koon.
4. Sculpture coarsely cancellate, interstices compound, i.e. large, subdivided by a single intermediary radial and several fine concentric threads to form secondary inter¬stices, each of which possesses a pit or pair of pits. Generally the ventral pair of secondary interstices within each main interstice contain radially elongate pits. This sculpture is clearly a modification of the simple form described under 2, where some of the concentric threads have become enlarged. This produces a coarser secondary cancellation which overlies a sculpture similar to that of group 2. It is found in E. thorektes and E. tenuicostata.
Initially most species possess concentrically elongate pits in the juvenile shell which gradually develop into their adult form. The above patterns of intritacalx pitting usually begin to develop near the start of the adult shell. With growth and the development of intermediary radial ribs the intritacalx pits frequently divide radially. In species with radially elongate pits this results in the formation of inverted V-shaped pits which subsequently split in two. The progressive development of interstices and intritacalx pits with growth of the shell is shown diagrammatically for E. natalensis and E. koon

Animal having the snout large, tentacles long, eyes on distinct peduncles ; mantle forming a tubular process extending beyond the anterior anal slit in the shell; having epipodial papillae, and the foot oval. Central tooth of radula large, quadrangular ; the inner 4 lateral teeth long and narrow ; the fifth large, bicuspid, its upper part bent horizontally ; uncini numerous. Shell oval, obliquely conical, the recurved apex directed backward ; front slope with a deep incision in the margin. A distinct anal fasciole extends upward from the fissure, sculptured differently from the other ribs of the surface ; surface latticed ; no septum or deck inside.
From the Carboniferous to Recent; many species are known from the Tertiary. The Recent species of Emarginula s.s. number about sixty, and are recorded from the Mediterranean, the Atlantic, the Gulf of Mexico, and the Indo-Pacific. They live from the upper laminarian to the coralline zone.
Vernacular Name.—Slit-limpet.