Argopecten hakei (Hertlein, 1925)
HERTLEIN, L. G. 1925. Pectens from the Tertiary of Lower California. Proceedings of the California Academy of Sciences [4th Series], 14 (1): 1-35, pls. 1-6. [p. 18, pl. 4, figs. 1, 3]
1925 Pecten (Plagioctenium) hakei Hertlein, 1925
L. G. Hertlein, 1925, plate 4.
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«Shell moderately arched, coarse and thick, slightly longer than high. Right valve ornamented by about 23 or 24 rounded to slightly flat-topped ribs, separated by narrower, round-bottomed interspaces, both the interspaces and ribs crossed by concentric incremental lines, and, in some cases, by rather strong lines of growth; anterior ear with a large byssal notch, and sculpture consisting of about five or six radiating riblets, crossed by concentric incremental lines; anterior and posterior margins of valves smooth except for concentric incremental lines; ventral margin rounded ; posterior ear ornamented by about eight radiating riblets and by lines of growth, the posterior edge of the ear forming nearly a right angle with the hinge line. Left valve convex, higher at the umbo than the right valve, and ornamented by about 24 or 25 squarish, flattopped, rounded ribs, separated by narrower, round-bottomed interspaces, the whole valve sculptured by concentric lines of growth; ears slightly concave, ornamented by about six or seven radiating riblets. Altitude 90 mm., longitude 95 mm.; diameter of right valve approximately 15 mm. ; apical angle of right valve approximately 114°.
Type: Right valve, No. 40 (L.S.J.U. type collection), from Loc. 47 (L.S.J.U.), Turtle Bay, Lower California; Paratypes: No. 41 (L.S.J.U. collection) and Nos. 1773, 1774 (C.A.S. collection), B. F. Hake collector; Salada, Pliocene. This species is also found at Loc. 46 (L.S.J.U.), post-Eocene sandstone, at north edge of a tilted mesa about five miles north of Abreojos Point, Ballenas Bay Quadrangle, Lower California, B. F. Hake collector; Salada, Pliocene; also Loc. 42 (L.S.J.U.) above San Juan Arroyo, about five miles southwest of Jesus Maria, Jesus Maria Quadrangle. Lower California, C. H. Beal collector; Salada, Pliocene. Pecten hakei differs from P. cerrosensis mendenhalli Arnold in its larger size, more numerous ribs and stronger concentric sculpture and large byssal notch. It differs from P. purpuratus Lamarck in bearing more numerous ribs, and in having a less rounded outline; also in lacking the lateral serrations on the radial ribs which characterize P. purpuratus. From P. cerrosensis Gabb, proper, it is distinguished by the much larger byssal notch in the anterior ear of the right valve, by the strongly sculptured ears, which, except for growth lines, are smooth in P. cerrosensis, and by the number of ribs, 23 to 24 in the present species rather than 18 to 20 in the species described by Gabb. This species is named in honor of Mr. B. F. Hake, who collected considerable material which has added to the knowledge of the stratigraphy of Lower California». LEO GEORGE HERTLEIN, 1925
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