Patinopecten oregonensis cancellosus E. J. Moore, 1963
MOORE, E. J. 1963. Miocene Marine Mollusks from the Astoria Formation in Oregon. United States Geological Survey Professional Paper, 419: 1-109, pls. 1-32. [p. 65, pl. 17, figs. 6, 8, 9; pl. 18, figs. 1, 4]
1963 Patinopecten oregonensis cancellosus E. J. Moore, 1963
E. J. Moore, 1963, plates 17 and 18.
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«The right valve of Patinopecten oregonensis cancellosus has 14 to 18, most commonly 14 or 15, flat-topped undercut ribs and interspaces usually of equal width, but 1½ times as wide on the largest specimens. The right anterior ear has a moderately deep byssal sinus above which are 3 or 4 imbricated ribs. The right posterior ear is sculptured by 4 to 6 imbricated ribs. The left valve has 13 to 16, most commonly 13 or 14, evenly rounded high ribs which may in some places be slightly flattened. Interribs are present on some specimens, usually near the posterior and anterior margins of the shell. The left anterior ear, entire on only 1 specimen, has 9 fine ribs; the left posterior ear has 6 or 7 ribs equal in width to those on the anterior ear. The entire surface of the disk of the left valve has an imbricated, lamellar microsculpture present only on well-preserved specimens; this sculpture is apparently not present on the right valve and is the same microsculpture seen on left valves of P. propatulus and Vertipecten fucanus.
Holotype: USNM 563242, pI. 18, fig. 4
Type locality: (loc. 187) Dredgings from the Miocene rocks, Coos Bay, Oreg. Patinopecten oregonensis oregonensis (Howe) (1922, p. 98-99, pI. 11, fig. 1, pI. 12, figs. 1, 2) has been collected from the Empire formation (Pliocene?) at Coos Bay, Oreg. It is a heavier shelled form than P. propatulus, has higher ribs, which are undercut, and also has a wider umbonal angle than P. propatulus.
P. oregonensis cancellosus differs from P. oregonensis oregonensis by having fewer ribs separated by wider interspaces and larger ears bearing a wider and deeper byssal sinus. The left valve of P. oregonensis cancellosus is more inflated than P. oregonensis oregonensis and has fewer ribs, and these ribs are higher and usually less rounded. P. oregonensis cancellosus reaches a larger maximum size than any of the speciInens of either P. propatulus or P. oregonensis oregonensis in the collections in the U.S. National Museum; the largest specimen is about 170 mm high and 190 mm wide. P. oregonensis cancellosus differs from P. propatulus by having a heavier shell and fewer ribs on both valves, and these ribs higher and more strongly developed than on P. propatulus. In addition the ears on both valves of P. oregonensis cancellosus are larger than on P. propatulus and the byssal sinus is wider and deeper. P. oregonensis cancellosus resembles P. coosensis (Shumard) from the Empire formation (Pliocene?) of Coos Bay, differing only in the number of ribs. P. oregonensis cancellosus has 14 to 18 ribs on the right valve and 13 to 16 on the left valve, whereas P. coosensis has 24 to 29 and about 27, respectively. P. oregonensis cancellosus has only been collected from the dredgings at Coos Bay, but it has been found associated in rock with known Miocene mollusks and is therefore known to have been a Miocene species. Locality: 187»
ELLEN JAMES MOORE, 1963
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