Most of the shells of this genus are small; some are elevated, and
others of a widely-depressed conical form.
Shell conical, recurved; summit entire; slit, or more or less hollowed
on the anterior side; a muscular impression in form of a horseshoe, open
behind and thicker at the beginning.
Emarginula Blainvillii.
E. marginata.
E. fissura.
E. rubra.
_E. Blainvillii._ Blainville’s Emarginula.
Shell with the notch or slit in the middle of the back, and not
extending to the margin.
_E. fissura._ The slit Emarginula. Pl. 32, fig. 5.
Oval, compressed, summit well marked, with reticulated striæ and ribs;
fissure extending half way from the margin to the summit; exterior light
brown, interior white.
_E. marginata._ The marginated Emarginula.
More compressed than the preceding; summit distinct, anterior margin
formed like a gutter.