Pecten (Pecten) andersoni gonicostus P. D. Trask, 1922
TRASK, P. D. 1922. The Briones Formation of middle California. University of California Publications, Bulletin of the Department of Geological Sciences, 13 (5): 133-174, pls. 1-8. [p. 149, pl. 1, fig. 5]
«PECTEN (PECTEN) ANDERSONI GONICOSTUS, n. var.
Plate 1, figure 5
Type.— No. 12370, Univ. Calif. Mus. Pal.
Shell small to medium in size, subcireular, nearly equilateral; dorsal margins gently concave; anterior dorsal margin longer than posterior; ventral margins strongly arcuate; right valve gently convex, and possesses about seventeen subangular "V" shaped ribs; interspaces wider than ribs; hinge line about threefifths width of shell; ears about equal in length; anterior ear with five ribs; posterior ear with four fine subangulate ridges, with interspaces wider than the ridges; byssal notch prominent. Dimensions.—Type specimen U. C. no. 12370; alt., 29.7 mm.; width, 30.2 mm.; length of ears, 18 mm.; apical angle, 100°. Occurrence.— Briones formation, U. C. loe. no. 1176. This species resembles P. andersoni Arnold, [20] but it differs from the latter in that the right valve is less convex, the ribs are less prominent, the interspaces are wider, and the ears are shorter and broaden»
[20] Arnold, U. S. G. S. Prof. Paper 47, p. 82, pl. XXIV, figs. 5-8, 1906.
PARKER DAVIES TRASK, 1922
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P. D. Trask, 1922, plate 1.
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