Cerion piraticus Clench, 1937

Original Description

"Cerion (Strophiops) piraticus new species         

Plate III, fig. 1.

Description.--Shell large, heavy, smooth to costate, usually rimately umbilicate, sometimes with the perforation closed. Color externally a porcelaneous white, with no indication of mottling in a large series from several localities. Interior of aperture white to pale brownish and pur­plish. Whorls 10½ to 11, flat-sided. Body whorl usually the widest. Nuclear whorls glass-like. Spire somewhat extended, tapering convexly to the summit. Angle of spire variable, but approximately 75°. Aper­ture subcircular, slightly expanded, usually colored, and with a very much thickened lip. Parietal area glazed but not built forward. Parietal wall supporting a central, large tooth which is not, however, continued back­ward. Columella heavy, supporting a flattened tooth which continues backward for a whorl and appears as a twisted columella. Umbilical area deeply excavated, the rimation not deep. Sutures only slightly indented. Sculpture of irregular, somewhat coarse growth lines. Generally the shells are smooth, with the exception of the growth lines, though two localities possessed strongly costate shells, the costae numbering about twenty on the body whorl.

MEASUREMENTS (in millimeters)

Length               Width                       Aperture

  39.6                   19.0                      10.0 X 9.5         Holotype

  42.8                   19.1                        9.8 X 8.0         Paratype

  47.0                   21.4                      11.5 X 9.0                 "

  43.0                   20.5                      11.0 X 8.5                 "

  40.5                   18.2                      10.5 X 8.5                 "

Holotype.-Mus. Compo Zoo1., no. 57,926, Southeast Point, twelve miles southeast of Abraham's Bay, Mariguana Island. Paratypes from the same locality and additional paratypes from the following localities, all on Mariguana: Timber Bay; Voisey Well Point; Abraham's Bay settle­ment; Upper Point; Abraham's Hill; Horse Pond; Tatch Ground Point; Golden Rock; Northeast Point; Booby Cay.

This species is a member of the regina assemblage and related both to C. regium of Castle Island and C. utowana of East Plana Cay. It differs from both by being almost imperforate, lacking all trace of color (as found in C. utowana) and having both the parietal and columella teeth somewhat reduced. In general outline it is quite similar to C. regium, differing only in being somewhat smaller. From C. utowana it differs in shape, not possessing the more tapering cone of this latter form.  It dif­fers from both in the extraordinary development of the lip, with the outer or palatal margin extending considerably beyond the whorl above.

A very large fossil specimen was found at Upper Point, one mile south of Abraham's Bay. This measured 55.9 mm. in length, which exceeds any known Cerion. This specimen was collected in the aeolian rock, and is quite possibly of post­pleistocene age.

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