Perspective shell

Solarium \So*la"ri*um\, n.; pl. {Solaria}. [L. See {Solar}, n.]
   1. 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.
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   2. (Zool.) 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}.
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Perspective \Per*spec"tive\ (p[~e]r*sp[e^]k"t[i^]v), a. [L.
   perspicere, perspectum, to look through; per + spicere,
   specere, to look: cf. F. perspectif; or from E. perspective,
   n. See {Spy}, n.]
   1. Of or pertaining to the science of vision; optical. [Obs.]
      --Bacon.
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   2. Pertaining to the art, or in accordance with the laws, of
      perspective.
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   {Perspective plane}, the plane or surface on which the
      objects are delineated, or the picture drawn; the plane of
      projection; -- distinguished from the {ground plane},
      which is that on which the objects are represented as
      standing. When this plane is oblique to the principal face
      of the object, the perspective is called {oblique
      perspective}; when parallel to that face, {parallel
      perspective}.

   {Perspective shell} (Zool.), any shell of the genus
      {Solarium} and allied genera. See {Solarium}.
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