To view the shell in 3 orientations. To see a SEM image of the protoconch.
Photograph: (Jung, 1989, Fig. 264.13) Scale bar is 1.6 mm. Image is of NMB H17248. NMB locality 17451: La Bomba, Río Banano, Limón Province, Costa Rica; Río Banano fm. Height: 11.1 mm; width: 6.1 mm.
Synonyms: Planaxis crassilabrum Guppy, 1874, p. 411, pl. 18, fig. 13; Strombina crassilabrum (Guppy), Woodring, 1928, p. 341; Strombina (Sincola) crassilabrum (Guppy), Jung, 1969, p. 508, pl. 53, figs. 14-20.
Morphologic Description: Of small size, moderately stout. Protoconch with a little more than 3 volutions; its outer lip sinusigerous. Teleoconch whorls up to 6. The first 2 to 4 teleoconch whorls are sculptured by straight, orthocline, axial ribs numbering 9 to 12 per whorl. Adapically these ribs are somewhat thickened; their interspaces are wide. The profile of the sculptured whorls is straight. Subsequent whorls smooth except for faint, slightly prosocline growth lines; their profile is somewhat convex. Outer lip moderately thickened, somewhat flaring and extended adapically. Its inner surface usually with a few denticles. Adjoining the posterior canal there is a callous ridge. Columellar callus inconspicuous to moderately well developed, with a few elongated denticles. Base of body whorl constricted, sculptured by a varying number of spiral cords. Dorsal hump inconspicuous to moderately well developed. Hump to the left of the aperture inconspicuous. Ventral side of body whorl somewhat flattened. Anterior canal short, recurved.
Lectotype: USNM 115492 (Matura, northeastern Trinidad, Matura shell bed of Talparo Formation, Pleistocene).
Distribution: Early Pliocene: Melajo Clay Member of Springvale Formation, Trinidad; Courbaril beds of upper Morne l'Enfer Formation, Trinidad; Rio Banano Formation, Costa Rica; beds of early Pliocene age according to an unpublished geological map supplied by Hermann Duque-Caro, Northern Colombia. Pleistocene: Matura shell bed of Talparo Formation, Trinidad.
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