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Species / Anchura Horreana

Anchura Horreana


Original description of Anchura horreana by Stephenson, 1952:

  • ”Shell of medium size, turreted, with spiral angle of about 30°; outer lip greatly expanded in the adult stage. Protoconch not preserved. Suture closely appressed, deeply impressed. Whorls about 7 (estimated), moderately and regularly convex in lateral profile, ornamented with spiral and axial ribs, the latter dominant. On the main part of the body whorl the axials number 18 or 19; the three axials nearest the beginning of the expanded wing are weakly developed, and no axials are present on the wing; the axials are sinuous in trend, with the curve convex forward on the base and concave forward above; they die out well down over the broadly rounded base. Six or seven of the axials nearest the expanded wing each bears a node on the inflated part of the whorl, 2 or 3 of which are moderately prominent. The penultimate whorl bears 15 nearly direct, round-crested axials, which are a little narrower than the separating interspaces. The main body whorl exhibits about 24 narrow, closely spaced nonprominent to obscure spiral ribs, which are most sharply developed on the basal slope and are least conspicuous on the inflation above. The outer lip is thick and expands broadly and prominently forward, curving upward at the outer corner in the form of a projecting spur of undetermined maximum lenght; there is also a slight rounded projection at the outer lower corner. Four of the small ribs on the body diverge and increase in strength as they pass out on the extended lip. In alinement with the afore-mentioned nodes on the body whorl is a prominent, thick rib that traverses the upper part of the lip and curves upward centrally on the outer spur; several secondary spirals traverse the first interspace below this rib. Seven or 8 obscure, narrow spirals are present on the penultimate whorl. The aperture is long-lanceolate, with an acute, slightly rounded angle at the rear and a narrow, slightly twisted siphonal canal at the front; the point of this canal is broken away. Thick, smooth callus spreads away from the aperture in all directions, covering the inner surface of the outer wing and passing forward on the parietal wall and upward onto the penultimate whorl.”

Locus typicus: 0.5 mile south and 0.75 mile west of Star School, northeastern Grayson County, Texas, USA

Stratum typicum: Templeton Member, Woodbine Formation, Cenomanian, upper Cretaceous

Dimensions Incomplete holotype: height 36+ mm; diameter, exclusive of the wing, about 20 mm, diameter, including the wing, 36 mm.

References


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