Chlamys behringiana colvillensis McNeil 1967
MACNEIL, F. S. 1967. Cenozoic pectinids of Alaska, Iceland, and other nothern regions. United States Geological Survey Professional Paper, 553: iv, 57 p., pls. 1-25. [p. 26, pl. 18, figs. 5, 7]
1967 Chlamys (Chlamys) behringiana colvillensis McNeil 1967
F. S. MacNeil, 1967, plate 18.
|
«Pecten (Chlamys) n. sp., Dall, 1920, U.S. Geol. Survey Prof. Paper 125-C, p. 31.
Pecten sp., MacNeil, 1943, Jour. Paleontology, v. 17, no. 1, p. 86, pl. 12, fig. 4. Chlamys hindsii, MacNeil, 1957, U.S. Geol. Survey Prof. Paper 294-C, p. 114, pl. 14, fig. 1. Description.— Shell subrounded and medium inflated. Anterior ear of the right valve, the only one known, moderately narrow; byssal area correspondingly wide. Byssal sinus moderately broad and well rounded at its inner extremity, not angulate. Dorsal margins nearly straight and anterior margin slightly longer; dorsal slope very narrow. Bibs strongest medially where they are broad, straight sided, and crudely three crested; medial interspaces broad and round bottomed, about as broad as the ribs. Terminally the ribs are narrower and distinctly two parted; the most anterior and posterior ribs are smaller and single. Left valves, known only from scraps, have moderately high ribs that are slightly narrower than interspaces; ribs are usually three crested. Reticulate or metal lathelike microsculpture present between the smaller terminal ribs but not between medial ribs; medial interspaces have concentric lines only, and those of the left valve are slightly frilled or scaly. Discussion.— This form is here made a subspecies of C. beringiana, but it could just as well stand as a distinct species. No other fossil pectinid from Alaska has the combination of characters exhibited by this form. The weakly inflated right valve and the three-crested nature of the medial ribs might suggest a relationship with C. rubida, as I believed originally. On the other hand, the slightly longer anterior dorsal margin suggests a relationship with C. beringiana. Until enough specimens have been found to show the full range of variation, it would be useless to speculate further on the exact relationships of this subspecies. Types: The holotype (USNM 591912), an incomplete right valve, has a height of 62 mm and a length of 58 mm. The figured fragment from Nome is numbered USNM 644968. Type locality: Colville River at Ocean Point, about 8 miles below the mouth of the Kikiakrorak River, northern Alaska, Gubik Formation (horizon probably early Pleistocene), USGS D306. Other occurrences: Submarine Beach (late Pliocene or early Pleistocene), Nome, Alaska, USGS M1256; Submarine Beach or Intermediate Beach (middle Pleistocene), Nome, Alaska USGS 7477.» FRANCIS STEARNS MACNEIL, 1967
|