Patinopecten haywardensis (Lutz, 1951)
LUTZ, G. C. 1951. The Sobrante Sandstone. University of California. Publications Department of Geological Sciences Bulletin, 28 (13): 367-406, pls. 15-18, 3 text figs. [p. 386, pl. 17, figs. 9, 10]
1951 Pecten (Patinopecten) haywardensis Lutz, 1951
G. C. Lutz, 1951, plate 17.
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«Shell of large size, suborbicular, compressed, equivalve; apical angle about 115 degrees for specimen 60 mm. high, about 130 degrees if measurements taken tangential to dorsal slope of specimen 120 mm. high; dorsal slope slightly concave; hinge margin less than half width of shell; right valve with 17 or 18 square, flat-topped, radiating ribs, some with slight medial sulcus; interribs as wide or slightly rvider than ribs, square, with vertical side walls, some with medial interriblets; entire surface ornamented with numerous fine growth lines; anterior ear longer than posterior ear, nearly flat, ventral half slightly convex, dorsal halfcovered with from 5 to 6 well-defined radiating riblets crossed by numerous growth lines: byssal notch slightly less deep than in P. caurinus, deeper than in P. propatulus: posterior ear slightiy and evenly concave, ornamented by 7 or 8 radiating riblets, posterior edge sloping at about 110 degrees from hinge margin; left valve with about 17 V-shaped ribs; anterior ear like P. caurinus, possibly with more concave ventral half of anterior edge; posterior ear slightly and evenly convex. (Left valve notations from internal cast.)
Dimensions.— Holotype height 112 mm. (incomplete); width 130 mm. (incomplete); length of hinge margin 60 mm. Holotype antl paratype both from locality A-4566.
Holotype.— No. 34133. Paratgpe.— No. 34134. Occurrence.— Loc. A-4566. Remarks.— This species may be distinguished from P. caurinus by its much better developed riblets on the right posterior ear, a greater angle between the hinge margin and the posterior edge of the posterior ear, and also by its more squarely shaped ribs and interspaces which have vertical side walls, its slightly less deep byssal notch, a shorter hinge line in proportion to the width of the shell, and a greater number of ribs. (Grant and Gale, 1931, p. 195, have given the rib count of more than 25 Recent and Pliocene specimens of P. caurinus in the collections at Stanford University as between 16 and 20. Mr. E. J. Wilson and the author counted the ribs of the Recent specimens in the Stanford stratigraphic collection and found them to have not less than 20 and as many as 23.) P. haywardensis may be distinguished from P. propatulus by its larger apical angle, greater width of the hinge line in proportion to the width of the shell (P. propatulus has a hinge line proportionally much smaller than that of P. caurinus), a deeper byssal notch, and a greater number of riblets on the anterior ear. The ribs of P. propatulus are much higher than those of either P. caurinus or P. haywardensis, especially in the intermediate growth stage. The right posterior ear, both in P. caurinus and in P. propatulus, appears to be nearly flat, whereas that of P. haywardensis is decidedly convex.»
GEORGE CHAPMAN LUTZ, 1951
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«Holotype.— UCMP 34133.
Type locality.— UC A-4566. Alameda County, Calif. Sobrante Sandstone. Miocene. Comparison.— "This species may be distinguished from P. caurinus by its much better developed riblets on the right posterior ear, a greater angle between the hinge margin and the posterior edge of the posterior ear, and also by its more squarely shaped ribs and interspaces which have vertical side walls. its slightly less deep byssal notch, a shorter hinge Iine in proportion to the width of the shell, and a greater number of ribs. (Grant and Gale, 1931, p. 195, have given the rib count of more than 25 Recent and Pliocene specimens of P. caurinus in the collections of Stanford University as between 16 and 20. Mr. E. J. Wilson and the author counted the ribs of the Recent specimens in the Stanford stratigraphic collection and found them to have not less than 20 and as many as 23.) P. haywardensis may be distinguished from P. propatulus by its larger apicalbangle, greater width of the hinge line in proportion to the width of the shell (P. propatulus has a hinge line proportionally much smaller than that of P. caurinus), a deeper byssal notch, and a greater number of riblets on the anterior ear. The ribs of P. propatulus are much higher than those of either P. caurinus or P. haywardensis, especially in the intermediate growth stage." (Lutz, 1951, p. 386-387) Comments.— The holotype and paratype of P. haywardensis are molds from which the figured latex impressions were made. Patinopecten haywardensis may be distinguished by the narrow, high, square, widely spaced ribs on the right valve; none of the ribs are sulcated. Geographic range.—Middle California. Geologic range.— Miocene. Occurrence in California.— Sobrante Sandstone.» MOORE, E. J. 1984. Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae. United States Geological Survey Professional Paper, 1228-B: iv + B1-B112, figs. 1-2, pls. 1-42. [p. B80]
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Patinopecten haywardensis (Lutz); E. J. Moore, 1984, Tertiary Marine Pelecypods of California, plate 35, figure 4 (above); plate 36, figure 1 (below).
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