Posted: Jan 2026
Prunum avenaceum (Deshayes, 1844) The Shell That Never Was
Over the period 1834 to 1870 Kiener published a comprehensive collection of drawings and descriptions encompassing Lamarch’s collection of seashells housed at the Muséum d'histoire naturelle de Paris. Among the Marginellas Kiener presented none were identified as Marginella avenacea; but a Marginella avena was:
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*Valenciennes was briefly an assistant to Lamarck in 1814.
In 1844 Deshayes and Milne-Edwards published a culturally important tome on the history of Mollusks. Included was a long section describing 43 Marginellas (including those presented by Kiener). Deshayes did not include Marginella avena Kiener, but did include a species identified as “Marginella avenacea Kiener” with a description that matched Kiener’s M. avena and he illustrated by referencing Kiener’s plate 6, figure 24 (M. avena). It’s rather clear that Deshayes’ intent was to describe Kiener’s shell when he linked the name to Kiener, matched Kiener’s description, and referenced Kiener’s drawings. Apparently, a spelling error occurred (avena became avenacea), and a seemingly new species of Marginella entered the literature. And, unfortunately, it was uncritically treated as a valid species by many authors in the following years, although its genus name was changed to Hyalina (Morris, 1947; Abbott, 1954), Volvarina (Kaicher, 1981), and then to Prunum (Coovert, 1988). And, along the way a shell different than the one illustrated by Kiener began to be used to illustrate “avenacea.” The earliest example I could find is in Morris (1947). Here’s a comparison of Kiener’s shell to later illustrations of “avenacea.”
I could not find when or why a shell morphologically quite different than Kiener’s M. avena was introduced as being Deshayes’ “Marginella avenacea Kiener.” I suspect it may be related to the ambiguity surrounding Marginella bella, Conrad 1868 and Dall’s 1890 suggestion that Conrad’s shell represented three varieties:
Marginella bella Conrad; typical form – Fig. 9.a
Marginella bella var. inepta Dall; Fig. 8.d
Marginella bella var. bellula Dall; Fig. 8.e
Subsequent authors may have interpreted Deshayes’ use of the name Marginella avenacea as valid, but felt one of Dall’s varieties was the appropriate fit.
Marginella bella Conrad; typical form. Currently (Jan 2026) accepted by Molluscabase as a valid species of extinct fossil with the name Prunum bellum (Conrad, 1868). Be careful not to confuse the name with Prunum bellulum (Dall, 1890).
Marginella bella var. inepta Dall. Abbott (1974) notes that this shell is a fossil from Ballast Point, Tampa Florida and is not Dall’s 1927 Marginella inepta. WoRMS currently (Jan 2026) rejects Dall’s 1927 Marginella inepta as a misidentification and invalid junior homonym of his 1890 variety. Dall’s description of his 1927 shell (“apex bluntly rounded-conical … aperture nearly as long as the shell … pillar with three plaits”) clearly does not fit that of his var. inepta (apex pronounced conical … aperture ¾ length of the shell … pillar with four plaits). WoRMS accepts Hyalina discors (B. Roth, 1975) as the valid name for Dall’s 1927 shell.
Marginella bella var. bellula Dall. Dall’s discussion of his three varieties is rather ambiguous as to which one(s) were found only as fossils and which one(s) were “recent,” despite his introductory comment “Recent off the coast of North Carolina, living in 14 to 50 fathoms sand.” The recognition of Marginella bella and Marginella bella var. inepta as extinct fossils allows confirmation that Marginella bella var. bellula was Dall’s “recent shells” (living) and is today a valid species separate from Conrad’s M. bella. This conclusion is currently (Jan 2026) reflected in WoRMS by acceptance of the species name Prunum bellulum (Dall, 1890).
The striking resemblance of Dall’s Marginella bella var. bellula to the ambiguous shells presented by Morris, Kaicher, Abbott and others (Lipe, 1991, and Lee, 2009) is what leads me to suspect it was mistakenly used to illustrate Deshayes’ Marginella avenacea. My suspicion is supported by WoRMS’ current (Jan 2026) treatment of Prunum avenacea auct. and Volvarina avenacea auct. as synonyms of Prunum bellulum.
The current problem is that illustrations of the shell labelled Prunum bellulum that we might reasonably accept as valid are few. In my opinion this has happened because too few workers are aware that the taxon Prunum avenacea and illustrations of it represented a nonexistent shell (until it is realized that avenacea was a misspelling of avena), and as a result of WoRMS presenting an “unreviewed” image of a shell as Prunum bellulum that is clearly nothing like Dall’s Marginella bella var. bellula (Fig. 8.e), as the below comparison illustrates (a valid illustration is also included):
So, through error and confusion, the taxon Prunum (Marginella) avenacea erroneously came into the vernacular, was later erroneously illustrated, and eventually it was recognized that it never was.
See presentation of Prunum bellulum (Dall, 1890) for extensive illustrations of this taxon.
References:
Abbott, R. Tucker. 1954. American Seashells, Van Nostrand Reinhold Co.
Abbott, R. Tucker. 1974. American Seashells, Second Edition, Van Nostrand Reinhold Company.
Conrad, T. A. 1862 (Printed in 1863). Catalogue of the MIOCENE SHELLS of the Atlantic Scope. Proceedings of the Academy of Natural Sciences, pg. 564.
Conrad, T. A. (1868). Descriptions of Miocene shells of the Atlantic slope. American Journal of Conchology. 4(1): pg. 67.
Dall, W. H. (1890-1903). Contributions to the Tertiary fauna of Florida with especial reference to the Miocene silex-beds of Tampa and the Pliocene beds of the Caloosahatchie River. Transactions of the Wagner Free Institute of Science. 3(1), pg. 53.
Deshayes, G. P.; Milne Edwards, H. (1844). Histoire naturelle des animaux sans vertèbres, présentant les caractères généraux et particuliers de ces animaux, leur distribution, leurs classes, leurs familles, leurs genres, et la citation des principales espèces qui s'y rapportent, par J. B. P. A. de Lamarck. Deuxième édition, Tome dixième. Histoire des Mollusques. Pg. 454.
Kaicher, Sally D. 1973-1992. The Card Catalog of World-wide Shells. Published privately.
Kiener, L.C. 1834-1870. Spécies général et iconographie des coquilles vivantes..(continué par..P. Fischer). [Vols. 1-1: 1-165.]. Paris.
Lee, Harry G. 2009 Marine Shells of Northeast Florida. Jacksonville Shell Club, Jacksonville, Florida.
Lipe, Robert. 1991. Marginellas. The Shell Store, St. Petersburg Beach, FL.
Morris, Percy A. 1947. A Field Guide to Shells of the Atlantic and Gulf Coasts and the West Indies.