Argopecten mendenhalli (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. 84, pl. 25, figs. 2, 2a, 2b]
1906 Pecten (Plagiocternium) cerrosensis Gabb var.? mendenhalli Arnold, 1906
R. Arnold, 1906, plate 25.
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«Description.— Shell, when adult, averaging about 75 millimeters in altitude. Similar to P. cerrosensis in shape, convexity, and ribbing, but differing from the latter in being much smaller when adult, having fewer ribs (about 19 in the former, while the latter has usually 21 or more), much less prominent incremental lines, and a relatively longer hinge line.
Dimensions (of a medium sized specimen).— Alt. 43 mm.; long. 44 mm.; hinge line 28 mm.; diameter 17 mm. Although this form is closely allied to P. cerrosensis, it, nevertheless, should possibly have specific rank, as the differences between it and the typical P. cerrosensis are constant, and it belongs to a different geologic horizon. Not enough is known about its range and relations, however, to warrant a wider separation, at present, than that of a variety. The type is from beds of probable Miocene age (the equivalent of the Carrizo Creek beds) at Santa Rosalia, Lower California, directly west of and across the Gulf of California from Cuaymas, Mexico. At the type locality it is associated with the following fauna: Pecten carrizoensis, Pecten keepi, Cardium sp., Chione n. sp., Glycymeris sp., Ostrea sp. (large), Codakia sp. (very large), Semele (aff.) pulchra, Cardlta {Carditamera) sp., Strombus sp., Malea (aff.) ringens, echinoid spines, etc. The type of P. var. mendenhalli is U. S. N. M. No. 164849, and is from Santa Rosalia, Lower California, where it was collected by Doctor Merrill. Named in honor of Mr. Walter C. Mendenhall, of the United States Geological Survey. RANGE
Miocene. Santa Rosalia, Lower California (G. P. Merrill; E. Palmer); head of Garnet Canyon, about 12 miles north of the Mexican boundary, and Alverson Canyon, about 8 miles north of the Mexican boundary, San Diego County (W. C. Mendenhall; S. Bowers)».
RALPH ARNOLD, 1906
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