Cerion (Strophiops) pupilla Dall, 1905

Original Description

"Cerion (Strophiops) variabile new species. Pl. LVIII, figs. I, 6, 14.

Shell varying greatly in size, the typical form handsomely axially irregularly striped with opaque white, dark brown and light yellow brown; with two polished, partly transversely striate nuclear and eight subsequent polished whorls, of which the last is more or less distinctly ribbed, the preceding ones striate transversely or smooth, without spiral sculpture, umbilical chink almost closed. The body of the shell is subcylindric, the last whorl not contracted, sometimes very blunt as if truncate, the apex evenly arcuately domed, the apical portion not swollen. The peristome is simple, rounded, reflected, and the parietal part when fully adult is thick and continuous; the pa­rietal lamina is sharp, and one-third of the whorl long; the axial lamina is well developed only behind the pillar, the latter often seeming destitute of a lamina when examined from in front. The measurements are as follows (U. S. Nat. Mus., No. 120,011):

                        Height of

                        Shell                 Aperture            Max Diameter

Type form          24-21                7                      9.5-10.5 mm.

Var. saurodon    38                     13                     13            "

Var. pupilla        15.5-20.0           5.0-6.5              5.5-6.5     "

Cerion variabile var. pupilla; novo Pl. LVIII, fig. 1.

Shell small, thin and delicate, subcylindric, smooth, with two nu­clear and six and a half subsequent whorls; umbilicus closed; pa­rietal lamina sharply defined, the axial near the base of the pillar, just visible; the peristome is simple, hardly reflected, the parietal part thin; the anterior part of the pillar markedly excavated. This may prove with more abundant material to be a distinct species. U. S. Nat. Mus. No. 120,011b.

This species was at first identified as C. inflatum Maynard (Acklin Island), though the specimens were collected by the late Professor Northrop at Red Bay on the northwest end of Andros Island. It differs from inflatum by its cylindric or conic, not top-heavy form, the last whorl usually ribbed, those preceding irregularly striate or smooth; it has one more whorl, the parietal callus is not only con­tinuous but usually thick when fully adult; the parietal lamina rela­tively sharp and clean cut, the axial one invisible from in front; the umbilicus open instead of closed. The two forms referred to variabile as varieties are similarly colored and from the same locality, but represented by only three specimens. Notwithstanding the enormous difference in size it seems more prudent for the present to regard them as forms of one species." (Dall, 1905:440-441)

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