Argopecten ventricosus bramkampi (Durham, 1950)
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. 63, pl. 9, figs. 2, 4, 8]
1950 Aequipecten circularis subsp. bramkampi Durham, 1950
J. W. Durham, 1950, plate 9.
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«Shell of medium size, resembling A. circularis in general outline, but with high, prominent beaks; 19 ribs, wide and rounded, interspaces narrow and channeled at bottom; beaks laterally compressed and slightly overhanding hinge line, with ears sharply delimited by an impressed area; anterior ear of right valve with about four radial ribs; byssal notch deep and sharply pointed; posterior ear of right valve with extremely faint and fine radial ribs. Both ears of left valve with 6–8 fine radial ribs.
Holotype no. 30035, paratype no. 30045 (loc. A 1268).
OCCURRENCE: loc. A 1268 (Imperial formation), A 3594. RANGE: lower Pliocene. REMARKS: The material from loc. A 3594 is poorly preserved but appears to be conspecific with the much better material from the Imperial formation. This latter material because of its preservation has been made the type of the subspecies. The high, overhanging, laterally compressed beaks separate this subspecies from the typical form.» JOHN WYATT DURHAM, 1959
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«Holotype.— UCMP 30035.
Type Locality.— UC A1268. Imperial County, Calif. Imperial Formation, Miocene or Pliocene. Comparison.—The high, overhanging, laterally compressed beaks separate A. circularis bramkampi from the typical form. (Durham, 1950, p. 63) "The valves of C. circularis calli are more elongated and the ribs are more numerous and narrower than those of C. circularis bramkampi * * *." (Hertlein and Grant, 1972) Comments.— The holotype is a moderately thick-shelled, inequilateral, right valve with a very inflated umbonal area. The ribs are rounded and separated by small, deeply rounded interspaces that have imbricated, concentric lamellae; both the ribs and interspaces are crossed by looped, concentric lamellae near the ventral margin. Geographic range.— Sotthern California to Baja California Sur. Geologie range.— Miocene to Pliocene. Occurrence in the Californias.—Miocene or Pliocene: Imperial Formation; Pliocene: San Marcos Formation.» MOORE, E. J. 1984. Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae. United States Geological Survey Professional Paper, 1228-B: iv. B1-B112 p., figs. 1-2, pls. 1-42. [p. B36]
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Argopecten circularis bramkampi (Durham); E. J. Moore, 1944, Tertiary Marine Pelecypods of California, plate 9, figure 5.
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