Patinopecten kimurai yudaensis Masuda, 1960
MASUDA, K. 1960. On the Miocene Pectinidae from the Environs of Sendai; Part 16, Pecten kimurai Yokoyama and Palliolum cf. peckhami (Gabb). Transactions and Proceedings of the Palaeontological Society of Japan [N. S.], 38: 249-262, pIs. 29-30. [p. 256, pl. 30, figs. 1, 2]
«Patinopecten kimurai yudaensis
MASUDA, n. subsp. Plate 30, Figures 1, 2 Description:— Shell rather large, moderately thick, suborbicular, compressed, equilateral except for auricles; right valve a little more convex than left; radiately ribbed and forming an angle of about 100° at apex. Right valve gently inflated, with about 9, rather elevated, smooth, round-topped radial ribs, fine concentric growth lines and obtuse network; radial ribs narrower than their interspaces, divided into two or three, faint, fine radial threads by shallow longitudinal furrows near beak but usually tend to become obsolete downwards, and sometimes divided into rather distinct, two or three or rarely a little more riblets with shallow interspaces, one being usually larger than others; radial ribs near submargins low and slender, much narrower than their interspaces, sometimes dichotomous; interspaces between radial ribs gently rounded and smooth-bottomed. but rarely with a few, faint, fine longitutlinal striae near submargins; anterior auricle subequal to posterior, with wide and shallow byssal notch. rather wide byssal area, with fine concentric lines and a few, faint, fine radial threads, and posterior one similar to anterior in sculpture; hinge with rather distinct cardinal crura, wide and shallo\v resillial pit provided with rather distinct, wide-opening, short lateral ridges. Left valve gently inflated, with rather sharp, moderately elevated radial ribs, fine concentric growth lines and distinct, fine network; radial ribs narrower than their interspaces, usually sharp near beak but tend to become somewhat rounded towards ventral marginy rarely with a few, faint, fine longitudinal threads on their backs and flanks, and rarely dichotomous; interspaces between radial ribs gently rounded and smoothbottomed, rarely with a fine intercalary thread which usually appears near beak; auricles nearly equal, with fine concentric lines and a few, faint, fine radial threads, Interior surface of valves gently folded corresponding to external sculpture.
Dimensions:·— Table 1. Comparison and Affinity:— This subspecies differs from the other subspecies of the kimurai group by the radial ribs being narrower than their interspaces and sometimes divided into two or three or rarely a little more, rather distinct riblets in the right valve.
Type locality, Geological formation and Age:— Right river side of Mabechi-gawa at Yuda, Kintaichi-mura, Ninohe-gun, Iwate Prefecture (Lat . 40º19' N., long. 141º19'10''E.). Shiratori formation, Early Miocene. Depository:— Holotype, DGS. Reg. No. 1936. Paratype, DC~S. Reg. Nos. 1935, 2439 and IGPS. coll. cat. no. 17621. Ocurrence:— Shiratori formation at the type localitY and at Nisatai, Fukuoka-machi, Ninohe-gun, lwate Prefecture.» KÔICHIRÔ MASUDA, 1960
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K. Masuda, 1960, plate 30.
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