Chlamys parirregularis Nomura & Hatai, 1940
NOMURA, S. & K. HATAI. 1940. The marine fauna of Kyûrokusima and its vicinity, northeast Honsyû, Japan. Saito Ho-on Kai Museum of Natural History Research Bulletin, 19: 57-115, pls. 3-4. [p. 78, pl. 4, figs. 15, 16]
«106. Chlamys parirregularis n. sp. PI. IV, Figs. 15, 16
St. 4; 1/2 specimen, Reg. No. 13423. St. 7; 2/2 specimens, Reg. No. 14725. St. 8; 2 17/2 specimens, Reg. No. 14726. St. 9; 1 1 7/2 specimens, Reg. No. 14727. St. 10; 1/2 specimen, Reg. No. 14728. St. 16; 3 23/2 specimens, Reg. No. 14729. St. 17; 2/2 specimens, Reg. No. 13572. St. 18; 3/2 specimens, Reg. No. 13434. St. 19; 1/2 specimen, Reg. No. 14730
Description:— Shell small, attaining about 25 mm. in height, ovate in outline, hig-her than long; test rather thill, dirty orange; valves compressed, suhequivalve, equilateral, except for ears, sides of disc nearly straight, or very slightly concave near middle; dorsal margin evenly arcuated; beaks small, depressed, with an angle about 80°; hinge-line slightly longer than one-half of shell-Iength; ears very unequal, anterior one about double length of opposite one; right valve with about 25-30, subequal, more or less scaly radial riblets which are rarely provided with a smaller one between; interspaces wider than riblets themselves with minutely cross-hatched sculpture; anterior side more or less serrated; outer part of anterior ear marked by about five, distinct, scaly riblets, inner part of it with only coarse concentric, erect ridges which are concave toward byssal notch; posterior ear nearly rectangularly truncated with three, very fine scaly radials; byssal notch broad round on top; left valve almost similar to right valve, but possibly slightly flatter, and ribs less scaly and narrower; internal surface of both valves faintly grooved, corresponding to external sculpture.
Dimension of holotype:— Height 23.0 mm., length 20.0 mm., depth of both valves 8.0 mm., length of ears 12.0 mm. (The type is from Station 16).
Remarks:— Paratype specimens collected from the type locality give the following dimensions (in mm.). This species is closely related to C. irregularis (SOWERBY) from our seas, but the present shell is a smaller and thinner with fewer and subequal radial riblets; further the coloration greatly differs from SOWERBY's species. What Dr. YOKOYAMA figured as Pecten irregularis, on specimens from the Pliocene Kosiba bed, Musasi province¹ may be the present species.»
¹ YOKOYAMA, Jour. ColI. Sci., Imp. Univ., Tokyo, 39 (6), p. 133, pI. 13, figs. 1-3, 1920.
SHICHIHEI NOMURA & KOTORA HATAI, 1940
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S. Nomura & K. Hatai, 1940,
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