Neithea hanourensis Tashiro & Kozai, 1986
TASHIRO, M. & T. KOZAI. 1986. Bivalve fossils from the type Monobegawa Group (Part II). Research Reports of the Kochi University. Natural Science, 35: 23–54, pls. 1-10 [p. 36, pl. 4, figs. 11-13]
1986 Neithea (Neithea) hanourensis Tashiro & Kozai, 1986
«Material: -Holotype, KSG 3752, right valve, from Tatsukawa of Katsuura, Tokushima Prefecture.
Diagnosis: - Shell small, trigonal ovate, well inflated; umbo strongly prominent; primary ribs on the surface very weak for the genus; secondary ribs distinctly impressed with 3 in each interspace between the primary ribs. Description: - Shell small, trigonal ovate or roundly triangular in outline, well inflated, slightly taller than length; umbo very prominent, orthogyrous, pointed at nearly center of valve; anterior and posterior margins nearly straight, with almost the same length in each other; ventral margin broadly arched; apical angle is about 40°; surface ornamented with 6 primary ribs and numerous secondary roundtoped radial ribs which are somewhat narrower than their interspaces; primary ribs weak for the genus, slightly stronger than secondary ribs; secondary ribs are countable 3 in each interspace between primary ones; both lateral ears trigonal, moderate in size but slightly larger in anterior than in posterior. Remarks: - Single specimen, KSG 3752, 14.5 mm long, 14.7 mm high and 6.2 mm thick, is a well preserved right valve. The features of left valve and inner right valve are unknown. This species is similar to Neithea (Neithea) atava Römer and N. (N.) syriaca amanoi Hayami, in its 3 secondary radial ribs on the surface, but discriminated from N. (N.) atava in its small valve and less developed primary ribs, and differs from N. (N.) syriaca amanoi, in its prominent umbo and less developed primary ribs. Occurrence: -Fine grained sandstone of the Hanoura Formation of the Monobegawa Group at Tatsukawa of Katsuura, Kami-katsu-gun, Tokushima Prefecture; Upper Hauterivian.» MASAYUKI TASHIRO & TAKESHI KOZAI, 1986
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