What is "scorpion shell"

Pteroceras \Pte*roc"e*ras\, n. [NL., fr. Gr. ? a wing + ? a horn.] (Zo["o]l.) A genus of large marine gastropods having the outer border of the lip divided into lobes; -- called also scorpion shell.

n. any of numerous tropical marine snails that as adults have the outer lip of the aperture produced into a series of long curved spines