The Collaborative International Dictionary
perspective shell
Solarium \So*la"ri*um\, n.; pl. Solaria. [L. See Solar, n.]
An apartment freely exposed to the sun; anciently, an apartment or inclosure on the roof of a house; in modern times, an apartment in a hospital, used as a resort for convalescents.
(Zo["o]l.) Any one of several species of handsome marine spiral shells of the genus Solarium and allied genera. The shell is conical, and usually has a large, deep umbilicus exposing the upper whorls. Called also perspective shell.