Animal. Body elongated, prolonged behind the nucleus into a veritable tail, edged at its extremity by a vertical fin; head sufficiently distinct; two, long, conical tentacula; two sessile eyes; the organs of respiration and the nucleus entirely enveloped in a mantle with lobed edges.

Shell. Very thin, symmetrical, a little compressed, without spire, but with the summit a little reflexed posteriorly; aperture oval and entire. Inhabits the African, Mediterranean, and Australian seas. Three species.

GLOSSARY
OF TERMS USED IN CONCHOLOGY.

A.

Abbreviated, cut short.

Abdomen, the belly.

Acuminated, sharp pointed.

Aculeated, prickly.

Alated, winged.