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Species / Onustus Imperforatus

Onustus Imperforatus

Stromboidea


Original Description of Onustus imperforatus by Gabb, 1873, p. 241:

  • "Shell broad, trochiform, moderately elevated, whorls seven, convex above, margins squamose, suture minute, not undulated; upper surface covered by fine oblique irregular lines, sometimes dichotomous; under surface marked only by lines of growth. Umbilicus small, almost entirely covered by an expansion of the inner lip, its margin regularly rounded. Aperture sub-elliptical, outer edge acute."

Locus typicus: Dominican Republic

Stratum typicum: Miocene

Types: ANSP no. 3221

Xenophora imperforata holotype in Pilsbryi, 1922, pl. 31, figs. 3, 4

Comment Gabb, 1873, p. 241:

  • "About the size of O. exustus, but differs in its markedly smaller umbilicus with rounded margins, and in the non-stellate character of the squamose plate."

History and synonymy

1922

Description of Xenophora imperforata by Pilsbry, 1922, p. 385:

  • "The upper surface has the usual sculpture of fine, crowded, protractive wrinkles, which are not granulous. The last 3 1/2 whorls show no trace of attached objects, but several preceding whorls have little pits or facets where bits of shell or pebbles were no doubt attached, as in the recent X. indica (Gm.), though the agglutinating stage was shorter, not lasting beyond the size of about 8 mm. diameter. The base is nearly smooth, having growth-lines only. The narrow umbilicus is more than half covered by the dilated columellar lip. There is no spiral welt near the periphery, as in the recent X. caribea (Petit), which also has a wider umbilicus and carries more load.
  • Measurements: "Alt. 30, diam. 72 mm."
  • Types: ANSP no. 3221

Specimens from institutional collections

Onustus imperforatus Gabb, 1873; Gurabo Formation, Pliocene; Rio Gurabo 3, Cibao Valley, Dominican Republic; 1996; Coll. Stichting Schepsel Schelp, No. SSS27205

Onustus imperforatus Gabb, 1873; Gurabo Formation, Pliocene; Rio Gurabo 3, Cibao Valley, Dominican Republic; 1996; Coll. Stichting Schepsel Schelp, No. SSS27206


References

  • Gabb, W.M., 1873. Notes on the topography and geology of Santo Domingo. Trans. Am. phil. Soc., 15, 49-259
  • Pilsbry, H. A., 1922. Revision of W. M. Gabb's Tertiary Mollusca of Santo Domingo. Proc. Acad. nat. Sci. Philad., 73: 305-435, plts 16-47, 4 figs.
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