Pernopecten limaformis (White & Whitfield, 1862)
WHITE, C. A. & R. P. WHITFIELD. 1862. Observations upon the rocks of the Mississippi Valley which have been referred to the Chemung Group of New York, together with descriptions of new species of fossils from the same horizon at Burlington, Iowa. Proceedings of the Boston Society of Natural History, 8: 289-306. [p. 295]
1862 Aviculopecten limaformis White & Whitfield, 1862
1865 Pernopecten limatus Winchell, 1865
1865 Pernopecten limatus Winchell, 1865
Pernopecten limaformis (White and Whitfield); T. W. Hutchinson & E. C. Stumm, 1965, Upper Devonian and Lower Mississippian Pectinoid Pelecypods from Michigan, Ohio, Indiana, Iowa, and Missouri, plate 6, figures 2-4, 6-10.
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«Shell below a medium size, subovate in outline, higher than wide, greatest width below the middle. Valves very depressed, convex, the left a little the most ventricose; hinge fine short, less than half as wide as the body of the shell. Auricular extensions small, flattened, and subequal, separated from the body of tlie shell by shallow constrictions. Beaks minute, not elevated above the hinge. Anterior lateral margins straight to near the middle of the shell; basal margins broadly rounded; posterior straight, longer and more oblique to the hinge than the anterior. Lateral borders flattened, outside of a line passing from the beaks to the extremities of the basal line, the entire convexity of the shell being confined to the body of the shell, within these lines, which gives to the body of the valve an elongate triangular form.
Surface marked by fine, closely arranged concentric strise; entirely destitute of radiating strise. This shell differs from Avicula circulus, Shum., from the oolitic beds of the same locality, in being more elongate, in the less extension of the hinge line, in the flattening of the lateral spaces, and in being destitute of the fine radiating strias of that species. It closely resembles Pecten dissimilis, Flem., as figured by De Koninck, Anim. Foss., pl. 4, fig. 7, in general form and proportions, but that species is destitute of the peculiar flattening of the lateral borders, and is also radiately striate. This species is also found in the Chemung of Ohio.» CHARLES ABIATHAR WHITE & ROBERT PARR WHITFIELD, 1862
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