Carolinapecten urbannaensis (Mansfield, 1929)
MANSFIELD, W. C. 1929. New fossil mollusks from the Miocene of Virginia and North Carolina, with a brief outline of the divisions of Chesapeake Group. Proceedings of the United States National Museum, 74 (14): 1-11. [p. 6, pl. 2, fig. 2; pl. 3, fig. 2]
1929 Pecten eboreus urbannaënsis Mansfield, 1929
W. C. Mansfield, 1929, plates 2, 3.
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«The type locality of Pecten eboreus Conrad⁴ is Suffolk, Va. Dall ⁵ classified different mutations of the species and designated each by a varietal name. The form occurring at Suffolk he designated Pecten eboreus eboreus.
The new subspecies differs from the Suffolk form as follows: The ribs are lower and are separated by a shallower and less distinct interspace. Two to three fine radials lie within these interspaces. The ears are larger, the byssal notch deeper, and the radials on the ears are finer and less distinct. The new subspecies is an intermediate form between P. madisonius Say and P. eboreus eboreus Conrad. Dimensions.— Cotypes (Cat. No. 370829, U.S.N.M.), right valve, latitude, 107 mm.; altitude, 97 mm.; diameter, 17 mm. Left valve of another specimen, latitude, 104 mm.; altitude, 98 mm., diameter, 20 mm. Occurrence.— St. Marys formation, zone 2. U. S. G. S. station 3915, Urbanna, Va. (type locality); U. S. G. S. station 1/476a, Lanexa, Va., lower bed; U. S. G. S. station 1/233, Scotland Wharf, Va., right bank of James River, bed 10 to 16 feet above beach; U. S. G. S. station 1/540, Schmidts Bluff, right bank of James River, Va., lowest bed; Mount Folly, right bank of York River, Va.» ⁴ Conrad, T. A., Amer. Journ. Sci., ser. 1, vol. 23, p. 341, 1833.
⁵ Dall, W. H., Wagner Free lnst. Sci. Trans., vol. 3, pt. 4, p. 750, 1898. WENDELL CLAY MANSFIELD, 1929
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«Discussion.— This species is common to abundant in the Cobham Bay Member of the Eastover Formation. Small specimens that may be this species occur rarely in the Claremont Manor Member of the Eastover near Claremont, Surry County, Va. Gibson (1987, p. 50) reported the occurrence of C. urbannaensis as the "lowermost part of the Yorktown Formation" but the taxon is known only from the Eastover Formation. The Carolinapecten lineage appears first in the Eastover Formation (upper Miocene); it proliferated in the Pliocene on the Coastal Plain of North Carolina, South Carolina, Georgia, and Florida, and became extinct in the late Pleistocene. Its associated assemblages indicate its preference for subtropical and tropical marine conditions. Although the temperate taxon Chesapecten co-occurs with Carolinapecten in some areas, they generally are geographically separated even though it is clear that they occupied the same niche. Chesapecten is abundant from the Albemarle Embayment north, and Carolinapecten is abundant south of that basin.
Type information.— Lectotype (herein designated): USNM 370829. Type locality: Urbanna, Middlesex County, Va. (USGS 3915). Mansfteld's (1928 [1929]) type material consisted of two syntypes, a right and left valve. The herein selected lectotype is the right valve figured on his Plate 2, figure 2. Figured specimen.— A right valve (USNM 258362) from 0.8 km below Cobham Wharf, right bank of the James River, Surry County, Va. (locality 3, USGS 26052) Stratigraphic and geographic range.— Eastover Formation, Cobham Bay Member (Upper Miocene) in Virginia. Possible occunence in the Claremont Manor Member of the Eastover Formation (upper Miocene) in Virginia.» WARD, L. W. 1992. Molluscan bioestratigraphy of the Miocene, middle Atlantic Coastal Plain of North America. Memoirs of the Virginia Museum of Natural History, 2: 1-159, pls. 1-26. [p. 65]
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