Pecten (Lyropecten) ashleyi Arnold, 1906
ARNOLD, R. 1906. The Tertiary and Quaternary pectens of California. United States Geological Survey Professional Paper, 47: 1-264, 53 pls.[p. 122, pl. 47, figs. 1, 1a; pl. 48, fig. 1]
«PECTEN (LYROPECTEN) ASHLEYI n. sp.
PI. XLVII, figs. 1 and 1a; PI. XLVIII, fig. 1 1895. Pecten estrellanus Ashley (not of Conrad, 1857), Proc. Cal. Acad. Sci., ser. 2, vol. 5, 1895, p. 338.
Description.— Adult shell averaging about 150 millimeters in altitude, much longer than high, subequivalve, convex, inequilateral, the posterior portion of the disk being obliquely produced; sides concave above. Right valve with about 18 or 19 prominent, rather squarish, flat-topped (convex-topped near umbo) ribs which are more or less prominently sculptured by numerous thread-like, somewhat imbricated, radial ridges; interspaces narrower than ribs, channeled and ornamented by an intercalary riblet and, in the later stages of growth, by several imbricated radial lines; hinge line about one-half length of disk; anterior ear somewhat produced, prominently notched and sculptured by numerous imbricating incremental lines and several more or less prominent unequal radials; posterior ear slightly shorter than anterior, and similarly sculptured except with more, but less conspicuous, radials. Left valve slightly more convex than right and similar to it except that the ribs are slightly narrower and more convex, and the interspaces are correspondingly wider and generally have the bottom entirely sculptured with subequal radial lines, with the prominent intercalary lacking; ears subequal, rectangularly truncated and sculptured in a similar manner to the posterior ear of the right valve. Dimensions.— Alt. 152 mm.; long. 175 mm.; hinge line 85 mm.; diameter 65 mm.; apical angle 110º. This magnificent species is characterized and is distinguishable from allied forms by its great relative length and numerous ribs (P. crassicardo, a nearly allied form, having only 16 or 17). P. ashleyi is distinguishable from P. cerrosensis, with which it is generally associated, by the smaller number of ribs and the longitudinal sculpture of the same. In the Third street tunnel, Los Angeles, P. asheyi is associated with the following- fauna: Pecten opuntia, P. latiauritus, P. pedroanus, P. stearnsii, Glyphis densiclathrata, Nassa n. sp.;. Macoma sp. indet., Arca multicostata, Lima hamlini, Buccinum sp. indet., Neverita recluziana, Astarte sp., Priene oregonensis, Ostrea veatchii, Pleurotoma sp. indet., carditoid, coral, bird bone, crab's claw. This association of species indicates a horizon of the lower Pliocene. A fragment of a large specimen of P. ashleyi was found by Doctors Dall and Stearns in the low hills across the mesa three-fourths of a mile northeast of Pacific Beach, near San Diego. P. ashleyi is also found in the Pliocene at Cerros Island and San Fernando. The type is from Cerros Island, and is now in the collection of the University of California. Named in honor of Dr. G. H. Ashley, of the United States Geological Survey, whose pioneer work in the Santa Cruz Mountains added greatly to the knowledge of the West Coast Tertiary. RANGE
Pliocene. Cerros Island, otff Lower California (Univ. of Cal.): Temescal Canyon, Santa Monica Mountains. Los Angeles County (Rivers); Third street tunnel, Los Angeles (Hamlin); near Pacific Beach, San Diego (Dall, Stearns); San Fernando. Los Angeles County (Ashley); Cosmalia, Santa Barbara County (F. M. Anderson); Olinda, Puente Hills, Orange County (Eldridge).»
RALPH ARNOLD, 1906
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R. Arnold, 1906, plate 47.
R. Arnold, 1906, plate 48.
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