Late Pliocene to Middle Pleistocene; Extinct.
Original Description (from Smith, 1936, p. 136-137):
"Shell of medium size, whorls rapidly increasing in size, somewhat compressed; nuclear whorls smooth and apparently partly keeled, adjacent suture well impressed, later becoming less apparent and then broken or puckered by the obliquely variable and irregularly placed growth lines; spiral sculpture consisting after nucleus of regularly placed broad, flattish, indented, ribs, the interspaces narrower, these ribs on the body whorl varying more in width; base destitute of the spiral ribs but with slight indications of lines toward the periphery. Length 25 mm., breadth 20 mm., height 15 mm. Holotype in the writer's collection. Clewiston, Florida. Pl. 9, figs. 10, 10A.
Dall in his Tertiary Mollusca states on p. 379 that Sinum perspectivum does not antedate the Post-pliocene. S. polandi, apparently its progenitor, actually was dug out with a Pliocene assemblage. Named after William Poland, of West Palm Beach."
To access this description in its original formatting through the Biodiversity Heritage Library, click here.