Delectopecten peckhami (Gabb, 1866)
GABB, W. M. 1866-1869. Paleontology of California. Vol II. Cretaceous and Tertiary fossils. Geological Survey of California, 299 p., pls. 1-36. [p. 59, pl. 16, fig. 19a]
1866 Pecten (Pseudamusium) [sic] peckhami Gabb, 1866
1925 Pecten tairanus Yokoyama, 1925
1929 Pecten watanabei Yokoyama, 1929
1931 Pseudamusium [sic] (Hyalopecten?) beeshoense Kuroda, 1931
1956 Phallium [sic] peckhamioides Ozaki, 1956
1925 Pecten tairanus Yokoyama, 1925
1929 Pecten watanabei Yokoyama, 1929
1931 Pseudamusium [sic] (Hyalopecten?) beeshoense Kuroda, 1931
1956 Phallium [sic] peckhamioides Ozaki, 1956
W. M. Gabb, 1866, plate 16.
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«SHELL small, thin, subcircular, equivalve, or nearly so, slightly inequilateral; ears nearly equal in size. Upper valve, right ear not separated by any distinct line from the remainder of the surface; the corresponding ear of the lower valve has the same character; left ear flat, the swell of the shell commencing with nearly a right angle with its surface; corresponding ear of lower valves produced, separated from the body of the shell by a marked groove and a deep, narrow sinus. Surface marked by numerous small, irregular, concentric undulations, crossed by obsolete wavy radiating lines, which are most distinct on the ears.
From the bituminous shales of the Upper Miocene, on the Ojai Ranch, Santa Barbara County, where numerous specimens were collected by Mr. S. F. Peckham. Also found in the same formation on the shores of San Pablo Bay, west of Martinez, and elsewhere.
This shell belongs to the group (genus ?) Camptonectes, Agas., characterized by a lenticular form, closed all round, edentulous hinge, deep byssal sinus, and the minute radiating sculpture. The species is named after Mr. Peckham, in recognition of his valuable services rendered in collecting the fossils found in the vicinity of the Ojai Ranch.»
WILLIAM MORE GABB, 1866
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«Remarks: OMORI & UTASHIRO (1954) and UTASHIRO (1958) discussing this species in details, stated that the surface ornamentation is characterized by very fine radial threads and weakly undulated concentric growth lines, but the specimens with shell material lost are shown by the smoothly corrugated concentrics without radial threads, as seen in Pecten tairanus YOKOYAMA (1925). They also stated that the Pliocene specimens are usually larger than those of the Miocene.
Pecten tairanus YOKOYAMA (1925), P. watanabei YOKOYAMA (1929), P. (Hyalopecten?) beeshoense KURODA (1931) are all junior synonyms of this species. It is distinguished from the related recent species Palliolum (Delectopecten) randolphi (DALL) and P. (D.) macrocheiricola HABE in having finer surface ornamentation.» SHIKAMA, T. & T. KASE. 1976. Molluscan Fauna of the Miocene Morozaki Group in the Southern Part of Chita Peninsula, Aichi Prefecture, Japan. Science Reports of the Yokohama National University [Section II Biology and Geology], 23: 1-25, pls. 1, 2. [p. 21]
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Palliolum (Delectopecten) peckhami Gabb; T. Shikama & T. Kase, 1976, Molluscan Fauna of the Miocene Morozaki Group in the Southern Part of Chita Peninsula, Aichi Prefecture, Japan, plate 1, figure 18.
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«Delectopecten peckhami (Gabb) of Arnold is thin shelled, small, and possesses very weak to moderately strong concentric undulations. The concentric undulations are most apparent on specimens preserved in shale and subsequently flattened. Specimens collected from limestone and not flattened have barely discernable concentric undulations. The entire surface of the left valve has camptonectes sculpture; most of the specimens of right valves in the collections seem to have smooth shells, but patches of camptonectes sculpture are preserved on a few specimens. A few left valves have radial ribs 0.5 to 1 mm apart, which apparently disappear near the anterior and posterior margins of the shell. Four right valves were found to possess radial ribs crowded together at the anterior margin. The maximum number of such ribs counted was eight, and they seem to have been slightly spinose. No attempt is made here to separate these four specimens taxonomically. The presence or absence of radial ribs on parts of the shell other than the right anterior ear is considered of doubtful value in differentiation of species (Woodring, 1938, p. 38).
Figured specimen: Of Arnold (1906a, pI. 3, fig. 8), USNM 164839, pI. 20, fig. 4; pI. 21, fig. 2.
Locality: Monterey shale, Miocene, southeast of Pinole, Contra Costa County, Calif. (U.S. Geol. Survey Cenozoic loc. 2593.) Type of Pecten peckhami Gabb: Mus. Comp. Zoology 15045 was designated the lectotype by Stewart (1930, p. 120). The lectotype was not available for study and Arnold's usage is followed here. Type locality: Modelo formation, Miocene, Ojai ranch, Santa Barbara County, Calif. (Keen and Bentson, 1944, p. 92). Delectopecten was proposed by Stewart (1930, p. 118119) for small forms which do not have the posterior ear differentiated. The anterior ear of the right valve has 4 to 6, or perhaps more, radial ribs which seem to have been beaded. D. peckhami reaches a maximum height of about 25 mm and a width of 25 mm, as measured in the collections in the U.S. National Museum. Specimens reaching this maximum size were collected only from the shale of the Astoria formation; smaller specimens were collected from fine-grained tuffaceous siltstone. Howe (1922, unpublished, p. 83) said that this species is common in the Astoria shale at Astoria.
Slodkewitsch (1938, p. 113, pI. 42, figs. 2-7) records "Palliolum (Delectopecten) pedroanus var. peckhami (Gabb)" from the Kovachina and Vayempolka series of Kamchatka, and the Upper-Pil series of Sakhalin, U.S.S.R., from late Oligocene, Miocene, and possibly Pliocene. The forms illustrated by him are certainly at least very closely allied to D. peckhami in the Astoria. Localities: 1, 1c, 5, 7, 10-13, 15, 18, 23, 24, 26-29, 31, 32, 34, 43.
Occurrence elsewhere: Ternblor formation, lower and middle Miocene, Monterey shale, Miocene, and Modelo formation, late Miocene, California; possibly in Kamchatka, in late Oligocene to Pliocene (?) rocks.» 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. 67, 68]
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Delectopecten peckhami (Gabb) of Arnold; E. J. Moore, 1963, Miocene Marine Mollusks from the Astoria Formation in Oregon, plate 18, figures 2, 3; plate 20, figures 1, 3-5; plate 21, figure 2.
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«Remarks.-- The famous Palliolum (Delectopecten) peckhami (GABB) was recently fully discussed by T. UTASHIRO (1957, pp. 161-174, and 1968, pp. 320-330). According to him the specimens from our country are rather variable in form, and the distinction of them from the living species, P. (D.) macrocheiricola HABE is rather delicate. However the latter is practically distinguished from the former by its more glassy valves with less distinct concentric undulations.
Horizon.— The top of the Boroishi member, lower part of the Takaoka member, and the middle part of the Kibana subformation (lower Upper Miocene). Localities.— Takeuchi (Ml-X1), Kaichigo (Ml-2622, and Oriuzako) (Ml-7191), Miyazaki City; and Hosoye (Ml-1413), lkime mura, Miyazaki gun, Miyazaki Prefecture.» SHUTO, T. 1960. On Some Pectinids and Venerids from the Miyazaki Group (Palaeontological Study of the Miyazaki Group - VII). Memoirs of the Faculty of Sience, Kyushu University, [Serie D - Geology], 9 (3): 119-149, pls. 12-14, text-figs. 1-14. [p. 124]
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Palliolum peckhami (Gabb); T. Shuto, 1960, On Some Pectinids and Venerids from the Miyazaki Group, plate 12, figures 8, 9.
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«Description.— Shell averaging about 20 millimeters in altitude, subcircular, subequivalve, slightly inequilateral, thin, usually compressed, and with smooth margins. Right valve with the disk showing several small, more or less obsolete, irregular concentric undulations, numerous fine incremental lines and numerous fine obsolete radiating lines; hinge line about two-thirds of the longitude of the disk; anterior ear produced, separated from the body of the shell by a marked groove and a deep, narrow sinus, and prominently seulptured by 6 or 7 radiating ridges and numerous concentric elevated incremental lines; posterior ear not separated by any distinct line from the disk surface and ornamented only by concentric lines and obsolete undulations. Left valve similar to right except that the anterior ear is flat, the swell of the shell commencing with nearly a right angle with the ear surface; surface of anterior ear usually sculptured only by incremental lines, but occasionally with radiating striae also.
Dimensions.— Alt. 21 mm.; long. 21 mm.; hinge line 14 mm.; diameter 2 mm. As a rule only the molds or casts of this species are found in the shales in which they occur, and for this reason some of the characteristics of sculpture of the species are generally lacking. For example, in a large series of specimens examined, only two or three of the shells showed the radiating sculpture. The disks are generally obliquely distorted and often compressed, but the sculpture on the anterior ear of the right valve is almost always present and is quite characteristic. In California this species is found from the San Lorenzo formation (Oligocene) to the Monterey or middle Miocene. P. peckhami is found abundantly in the Monterey shale in Newell Creek canyon, 2 miles above Ben Lomond, Santa Cruz County, where it is associated with Arca montereyana Osmont, Corbula sp., Cytherea sp., Diplodonta n. sp., Venericardia (?) n. sp., Leda 2 n. sp., Phacoides sp., Semele n. sp., and Tellina cf. congesta Conrad. P. peckhami is also abundant in certain horizons of the Oligocene-Miocene of Washington, and Mr. Diller has found it in some shales in Oregon. It occurs near the base of the Oligocene-Miocene section between Bean and Restoration points, west of Seattle, King County, Wash., associated with Clypeaster (?) sp., Terebratula sp., and Teredo sp. At Freshwater Bay, Clallam County, Wash., it is found with Dolium petrosum Conrad, Fusus sp., Natica or Lunatia sp., Nucula cf. decisa Conr., Volutilithes n. sp., Dentalium substriatum Conrad, Phacoides acutilineatus Conrad, Solemya sp., Leda sp., and Marginella or Erato sp. Farther west along the Strait of Juan de Fuca, 1½ miles east of Gettysburg, Clallam County, Wash., P. peckhami is associated with Nucula sp., Leda n. sp., Dentalium substriatum Conrad, Natica sp., etc. One of the specimens of P. peckhami from near Bean Point, Washington, shows the anterior ear of the left valve to be ornamented by about 13 fine elevated radiating lines. Owing to the comparatively good state of preservation of the Washington specimens, nearly all of them show the minute concentric and radiating sculpture of the disk and ears in addition to the characteristic undulations of the former. RANGE
Miocene (middle). San Pablo, Contra Costa County (Gabb); southeast of Pinole, Contra Costa County (Lawson); Langley Hill, Alpine district, and south of Portola., San Mateo County; Felton and Ben Lomond, Santa Cruz County (Smith, Newsom, Arnold); Carmelo Valley, Monterey County (Lawson, Turner); Templeton, San Luis Obispo County (Fairbanks, F. M. Anderson); northwest of Tulare Lake, Tulare County (Watts); Ojai ranch, Ventura County (type locality) (S. F. Peckham); Big Panoche Creek, Fresno County (Turner); 4 miles south of McKittrick, Kern County (Eldridge).
Oligocene-Miocene. Ridge west of the headwaters of Boulder Creek and western slope of the south end of Ben Lomond Mountain, Santa Cruz County (Newsom, Arnold). In Washington at localities 4112a and 4113, between Bean and Restoration points, King County; locality 4121, Freshwater Bay; location 4120, 2 miles west of Port Crescent; locality 4114, 1½ miles east of Gettysburg, Clallam County (Arnold).» ARNOLD, R. 1906. The Tertiary and Quaternary pectens of California. United States Geological Survey Professional Paper, 47: 1-264, pls. 1-53. [p. 56, 57]
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Pecten (Pseudamusium) Peckhami Gabb; R. Arnold, 1906, The Tertiary and Quaternary pectens of California, plate 3, figures 6, 7, and 8.
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