Plagiostoma annulatus Trask, 1856
TRASK, J. B. 1856. Description of three new species of the genus Plagiostoma, from the Cretaceous rocks of Los Angeles. Proceedings of the California Academy of Sciences, 1: 86, pl. 3. [p. 86, pl. 3, fig. 2]
«P. ANNULATUS. Trask.
Plate III. Fig. 2. Shell compressed; obliquely rounded; five to seven broad concentric annulations; anterior margin obtusely rounded; ventral margin rounded; posterior margin somewhat produced; ventrally, and becoming slightly arched toward the dorsum; beak at the anterior half, and slightly raised above the line of the auricles; anterior auricle angular, with about twelve fine striae divergent from the umbones; posterior auricle subangulate, and truncate posteriorly. Length, one and five-twentieths of an inch; height, one and three-twentieths of an inch. Locality, San Pedro, Cal. Found with the preceding. There were three specimens of this species found — the left valve was used for the figure from its being the most perfect.»
JOHN BOARDMAN TRASK, 1856
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J. B. Trask, 1856, plate 3
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