Pecten (Patinopecten) oweni Arnold, 1906
ARNOLD, R. 1906. The Tertiary and Quaternary pectens of California. United States Geological Survey Professional Paper, 47: 1-264, pls. 1-53. [p. 63, pl. 8, figs. 1, 1a, 1b]
PECTEN (PATINOPECTEN) OWENI n. sp.
Pl. VIII, figs. 1, 1a, and 1b. «1888. Pecten pabloensis Cooper (not Conrad), Seventh Ann. Rept. CaL St. Min., 1888, p. 258 ( "Foxins, Santa Barbara County'' record, only).
1898. Pecten sp., Dall, Trans. Wagner Free Inst. Sci., vol. 3, pt. 4, 1898, p. 705, line 27. Description.— Shell averaging about 85 millimeters in altitude, slightly longer than high, inequivalve, equilateral, and with more or less serrate margins; base regularly rounded; sides somewhat concave above. Right valve much more convex than the left, with 15 or 16 subequal, strong, elevated, squarish ribs, which become more or less deeply medially sulcated after about 40 or 50 millimeters in length; interspaces about as wide as ribs, channeled and ornamented with more or less prominent rounded intercalary riblets; whole surface of disk sculptured by fine lines of growth; hinge line considerably longer than length of disk; anterior ear slightly longer than posterior, obsoletely radially ribbed, and with sharp incremental sculpture; byssal notch quite prominent and equal in width to about onethird width of ear; posterior ear rectangularly truncated and with prominent incremental, but nearly obsolete, radial sculpture. Left valve less ventricose than right; ribs quite high, narrow, and rounded; interspaces much wider than ribs, with round bottoms, and each ornamented by a prominent rounded intercalary rib; surface sculptured by numerous sharp, regular, concentric lines; ears slightly obliquely truncated and sculptured as those of right valve. Hinge as in P. caurinus. Dimensions.— Alt. 85 mm.; long. 90 mm.; hinge line 54 mm.; diameter 24 mm. This species is quite closely allied to P. healeyi, of which it is probably the precursor. It may be distinguished from the latter by its smaller size, greater convexity, fewer and stronger ribs, more prominent intercalary riblets on the right valve, and relatively much longer hinge line. P. oweni is found in a horizon which is probably low down in the Pliocene, and also in deposits, such as those at Foxin's ranch, Santa Barbara County, from which the type comes, that may be upper Miocene. Specimens of this species have been found in the lower part of the Purisima (Pliocene) formation north of the mouth of Purisima creek. There appears to be more or less of a gradation from P. oweni to P. healeyi as we go up in the Purisima formation. The rather convex, 17 and 18 ribbed forms of P. healeyi, mentioned as occurring at Lobitas and Purisima, seem to furnish a more or less intimately connecting link between the latter species and P. oweni. The type of P. oweni, which is figured, is now in the collection of the University of California. This specimen was labeled "P. pabloensis" by Doctor Cooper and furnished the erroneous record of P. pabloensis from "Foxins, Santa Barbara County'' (see Cooper, 1888, p. 258). In the Pliocene beds of Temescal Canyon, near Santa Monica, Los Angeles County, P. oweni is associated with P. stearnsii, P. estrellanus var. catalinae, P. cerrosensis and other Pliocene species. P. oweni is associated with the following possibly upper San Pablo (upper Miocene) fauna at the Double Eagle wells, in the Coalinga district, Fresno County: Tamiosoma gregaria, Pisania (aff.) fortis, Tresus (?) sp., Glycymeris patulus (?), and Saxidomus gibbosus. This fauna, although containing Tamiosorna gregaria, lacks the two most characteristic species of the San Pablo formation of this locality, viz, Pecten estrellanus and Ostrea titan. The beds at the Double Eagle wells represent the upper part of the San Pablo as developed in the Coalinga district, so that P. oweni may, therefore, be considered as only occurring in the upper part of the San Pablo, or, in other words, in beds transitional from the San Pablo (upper Miocene) to the Purisima (lower Pliocene). Just above the first railroad bridge across Wartham Creek, Fresno County, P. oweni is associated with the following fauna in beds probably representing about the same horizon as those exposed at the double Eagle wells above referred to: Saxidomus gibbosus, Chione n. sp. (large, coarse sculpture), and Tamiosoma gregaria. A 17-ribbed right valve of P. oweni was found 2 miles south of San Lucas, Monterey County, associated with Pecten estrellanus and varieties, Astrodopsis tumidus, Balanus estrellanus, etc. Named at the request of Mr. F. M. Anderson after Josiah Owen, of Los Gatos, Cal. RANGE.
Pliocene (lower). North of Purisima, San Mateo County (F. L. Hess); Olinda, Puente Hills, Orange County (Eldridge); Lonoak, Salinas Valley, Monterey County (U. S. Nat. Mus. locality 3830), (Hamlin); Lewis Creek, 9 miles below Priest Valley, Monterey County (locality 3833), (Hamlin). Temescal Canyon, Santa Monica Mountains, Los Angeles County (Rivers).
Miocene (upper?) Foxins, Santa Barbara County (University of California collection); Double Eagle wells, Coalinga district, Fresno County (Eldridge); railroad bridge across Wartham Creek, Fresno County (Eldridge); San Lucas, Monterey County (Hamlin; Arnold).» RALPH ARNOLD, 1906
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R. Arnold, 1906, plate 8.
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