Pecten (Pseudamusium) [sic] randolphi var. tillamookensis Arnold, 1906
ARNOLD, R. 1906. The Tertiary and Quaternary pectens of California. United States Geological Survey Professional Paper, 47: 1-264, 53 pls. [p. 139, pl. 48, figs. 3, 3a]
«PECTEN (PSEUDAMUSIUM) RANDOLPHI Dall var. TILLAMOOKENSIS n. var.
PI. XLVIII, figs. 3 and 3a. Description.— Shell resembling P. randolphi in outline and general characteristics. Disk ornamented by numerous more or less prominent, fine, radiating ridges, microscopic radiating striae, and incremental lines of varying prominence. The radiating ridges are narrow and thread-like, and appear to be more prominent anteriorly and near the lines of interrupted growth; the ribs are affected similarly to the disk by the interruptions in growth. The microscopic striae cover the whole surface of the disk and ribs and in a general way radiate from the umbo, but are seldom parallel to the ribs; on the portion of the disk and ear posterior to the umbo the striae are perpendicular to the lines of growth and are thus nearly parallel and not radiating. The right anterior ear has from 6 to 12 prominently imbricated radials.
Dimensions.— Alt. 30 mm.; long. 30 mm.; hinge line 17 mm.; diameter 7 mm. This variety appears to combine some of the characters of P. vancouverensis with P. randolphi, having the prominent radial sculpture of the former and the relatively large, undulated disk of the latter; the ears in P. var. tillamookensis are sculptured more nearly like the former, having from 1 to 6 more radials than P. randolphi. This variety generally occurs in deeper water, along the northwestern coast, than the typical form, being found at depths of from 400 to 800 fathoms. The type, U. S. N. M. 150233, is from off Tillamook Bay, Oregon, at U. S. F. C. Sta. 3346, at a depth of 786 fathoms. RANGE
Living. From north of Unalaska, 351 fathoms, to off Tillamook Bay. 736
fathoms. (U. S. Fish Commission.)» RALPH ARNOLD, 1906
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R. Arnold, 1906, plate 48.
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