\Pleu*rot"o*ma\, n.; pl. L. {Pleurotom[ae]}, E.
{Pleurotomas}. [NL., fr. Gr. ? the side + tomh` a cut.]
(Zo["o]l.)
Any marine gastropod belonging to {Pleurotoma}, and ether
allied genera of the family {Pleurotmid[ae]}. The species are
very numerous, especially in tropical seas. The outer lip has
usually a posterior notch or slit.