Euvola bella (Conrad, 1857)
CONRAD, T. A. 1857. Descriptions of three new genera; twenty-three new species middle Tertiary fossils from California and one from Texas. Philadelphia Academy of Natural Sciences Proceedings, 8: 312-336 [Reprinted in Dall 1909: 173-175]. [p. 312]
1857 Janira bella Conrad, 1857
1878 Pecten hemphilli Dall, 1878
1906 Pecten (Pecten) auburyi Arnold, 1906
1878 Pecten hemphilli Dall, 1878
1906 Pecten (Pecten) auburyi Arnold, 1906
Pecten (Pecten) bellus Conrad; R. Arnold, 1906, The Tertiary and Quaternary pectens of California, plate 31, figures 1, 1a.
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«Janira bella. Subtriangular; inferior valve convex, ribs 14 or 15, square, about as wide as the intervening spaces, very prominent, some of them with one or two longitudinal obsolete lines; disk finely wrinkled concentrically; upper valve flattened, deeply depressed towards the apex; ribs rather narrower than those of the opposite valve, obscurely bicarinated above, disk ornamented with close, fine, squamose, concentric wrinkles. Length 4 inches; heighth 3¾ inches.
Locality. — Santa Barbara, Cal. Dr. Newberry.» TIMOTHY ABBOT CONRAD, 1857
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«Comments.— The neotype is a double-valved specimen. The right valve has 16 ribs that are flat-topped, unequal in size, and separated by interspaces ranging in width from half as wide to wider than the ribs. Secondary ribs are in some of the subrounded interspaces. The right anterior auricle has a narrow, shallow byssal notch and one riblet; the right posterior auricle has no riblets. The left valve has 14 ribs subrounded at the anterior and posterior ends of the shell but flat topped on the rest of the shell. One rib is split close to the umbo. The interspaces are wider than the ribs and do not have secondary riblets. The entire shell has imbricated, concentric lamellae, and the auricles have no riblets.
Geographic range.— Middle California to Baja. California Sur. Geologic range.— Miocene to Pleistocene. Occurrence in the Californias.— Miocene and Piiocene: Purisima Formation (Arnold, 1906); Pliocene: Almejas (Minch and others, 1976), Carmen (Durham, 1950), Cebada and Graciosa Members, Careaga Sandstone (Woodring, 1950), Niguel (Vedder, 1960), Salada (Beal, 1948), and San Diego (Arnold, 1906; Hertlein and Grant, 1972) Formations, unnamed Pliocene on San Clemente Island (Vedder and Moore, 1976; Susuki and Stadum, 1978); Pliocene and Pleistocene: Fernando (Arnold, 1907a; Moody, 1916; Soper and Grant, 1932; Zinsmeister, 1970), Merced (Arnold, 1906), Pico (Waterfall, 1929; Winterer and Durham, 1962), Potato Harbor (Weaver and Meyer, 1969), and Saugus (Kew, 1924) Formations; Pleistocene: Lindavista Formation (Kennedy, 1973).» 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. [B69]
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Pecten (Pecten) bellus (Conrad); E. J. Moore, 1984, Tertiary Marine Pelecypods of California, plate 29, figures 1-4.
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«REMARKS: This species was not noted from this locality in Hanna and Hertlein's list (1927, p. 145) but was found during an examination of the original material. Inasmuch as it has not been found elsewhere within the Gulf of California collections, the possibility of it having been accidentally mixed in the collections was considered. Examination of matrix adhering to it revealed that the mineral assemblage present was the same as in other undoubted material from the locality and not the same as is found at San Diego or Cedros Island where this species commonly occurs.
Further examination of uncleaned material from this locality revealed two fragmentary and one very large complete right valve (PI. 7, fig. 5). This last specimen has a height of 109 mm high. During its later growth stages the ribs become somewhat lower and more rounded. The smaller specimen with both valves exactly matches some specimens of hemphilli from the type area. No specimens having the character of typical bellus were noted.» DURHAM, J. W. 1950. Megascopic paleontology and marine stratigraphy. In 1940 E. W. Scripps Cruise to the Gulf of California, Part II. Geological Society of America Memoir 43: 1-216, pls. 1-48. [p. 60]
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Pecten (Pecten) bellus var. hemphilli Dall; J. W. Durham, 1950, Megascopic paleontology and marine stratigraphy, plate 7, figures 3, 5.
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«Examination of a large number of specimens of both typical Pecten bellus Conrad and P. hemphillii Dall, from both Upper and Lower California, has convinced the authors that these two forms are merely extremes of an unbroken series, and belong to but one very variable species. The name bellus takes precedence by right of priority.
P. hemphillii has been said to differ from P. bellus in that the left valve is flat or concave in the former, rather than somewhat convex as in typical P. bellus, and in that the radiating ribs on both valves of Dall's species are more numerous and more highly elevated. In the series examined by us we find great variation in the combinations of these characters; no two adult specimens are exactly alike in appearance, and the extremes are perfectly united by intermediate forms. The number of ribs on the right valve varies from 14 to 18; the ribs vary greatly in width, elevation and prominence, and the convexity of the two valves is in no wise constant. Young examples, up to an altitude of 20 mm., are all very similar in appearance. Six paratypes of P. hemphillii, out of the original lot from Pacific Beach, near San Diego, have been examined in the course of this work. On the basis of the previously enumerated distinctions, certain of these specimens can be referred to Ball's species, while others are unquestionably the P. bellus of Conrad. One of the latter is herewith figured, together with illustrations of two of our specimens from Cedros Island. The type of P. hemphillii, as indicated by the illustration furnished by Arnold, is an intermediate form not exactly similar to either extreme of the series, although it inclines toward the narrow-ribbed variants. In the original description of P. hemphillii no reference was made to P. bellus, but a comparison was drawn with Pecten stearnsii Dall, a quite different form. There is, furthermore, neither stratigraphic nor geographic difference in the occurrence of the two extremes of the series, and there is no doubt that they are specifically identical. This species is excessively abundant in the Pliocene beds near Bernstein's abalone camp on Cedros Island, and it also occurs near Turtle Bay and Elephant Mesa. It is known from the Santa Barbara, Saugus and San Diego upper Pliocene formations, and from the Pico lower Pliocene formation of southern California.» JORDAN, E. K. & L. G. HERTLEIN. 1926. Expedition to the Revillagigedo Islands, Mexico, in 1925, VII. Contribution to the Geology and Paleontology of the tertiary of Cedros Island and adjacent parts of lower California. Proceedings of the California Academy of Sciences [4th Series], 15 (14): 409-464, pls. 27-34. [p. 430, 431]
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Pecten (Pecten) bellus Conrad; E. K. Jordan & L. G. Hertlein, 1926, Expedition to the Revillagigedo Islands, plate 32, figure 2; plate 33, figures 1, 2; plate 34, figures 2-4.
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«Found in the Pliocene at Santa Barbara, California (Conrad, Gabb, Yates Cooper, Arnold).
The description, measurements, and figures are of Gabb's type specimen of Janira bella (No. 960, Collection Academy Natural Sciences, Philadelphia), which was kindly loaned to the writer by Professor H. A. Pilsbry, Curator of Mollusca. P. stearnsii and P. diegensis are distinguishable from P. bellus by the more numerous (25 or 28 in the first, 20 or 22 in the second), narrower, sharper defined, perpendicular-sided, radiating ribs on the right valve, and by evenly rounded, prominently and evenly lamellated ribs of the left valve. P. hemphilli is distinguishable from P. bellus by its smaller size; by having on the right valve more numerous (15 or 16 in the former), round-topped, narrower, nearly perpendicular-sided, radiating ribs, which retain their prominence for their entire length, and by the less convexity of the disk, more numerous, narrower and more elevated radiating ribs of the left valve. P. hemphilli has the same depression below the apex in the left valve, but the less degree of convexity of the rest of the disk lessens the prominence of the depression, which is so marked in most specimens of P. bellus. P. dentatus is distinguishable from P. bellus by its smaller size, greater convexity of right valve, greater concavity of left valve, greater number of ribs, and by the auxiliary ribs in the left valve. After a careful comparison of a large series of P. bellus with Conrad's description and figure and Gabb's figure and type specimen, the writer has no hesitancy in adopting the synonymy given at the beginning of this article. Dall is of the opinion that Conrad's species and that of Gabb are different. This idea was probably caused by the exaggeration of the bicarination of the ribs in Conrad's figure. Several of the specimens of P. bellus examined by the writer show this bicarination to a greater or less degree, although as a rule the ribs are nearly smooth-topped. A large series of P. bellus and P. hemphilli show the differences enumerated in a previous paragraph to be constant for the adults. The young of both species up to an altitude of twenty millimeters are nearly identical in appearance.» ARNOLD, R. 1903. The Paleontology and Stratigraphy of the Marine Pliocene and Pleistocene of San Pedro, California. Memoirs of the California Academy of Sciences, 3: 1-420, pls. 1-37. [p. 104]
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Pecten (Pecten) bellus Conrad; R. Arnold, 1903, The Paleontology and Stratigraphy of the Marine Pliocene and Pleistocene of San Pedro, plate 21, figures 1, 2.
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