| New York State Museum - Science - 1857 - 364 pages
...somewhat arcuate ; foramen very narrow. Surface having about four rounded, slightly prominent folds on each side of the mesial sinus and elevation ; concentrically marked by fine, regular, closely arranged stride. This species resembles S. crispus of the Niagara group, but... | |
| Maryland Geological Survey - Geology - 1913 - 610 pages
...becoming linear towards the extremities where the shell is much extended. " Surface marked by from four to six strong and abruptly elevated plications...surface. In well-preserved specimens, finer longitudinal lines mark the surface of these lamellae. In ordinary specimens the concentric lamellae are more closely... | |
| Missouri. Division of Geological Survey and Water Resources - 1922 - 620 pages
...valve, and incurved at the apex; sinus deep, gradually expanding, and produced in front into a Imguiform extension. Dorsal valve convex towards the middle,...they are more distant, and are scarcely imbricate." — Hall, 1859. Remarks — -The Missouri specimens have 3 or 4 plications on each side of the medial... | |
| Geology - 1929 - 558 pages
...developed; surface with three to six elevated plications on each lateral slope; the plications are crossed by strong imbricating lamellae, which are abruptly arched in passing over the plications. Length 17 millimeters; width 30 millimeters. Common in the New Scotland limestone; rare in the Coeyrnans... | |
| Missouri. Division of Geological Survey and Water Resources - Geology - 1922 - 620 pages
...perlamcllosus Hall, 1859, Pal. NY, vol. III, p. 201, pl. XXVI, figs, la-i, kp, rt, 2a-g, 1861.1 Description — "Shell trigonal or semi-circular, more or less extended...they are more distant, and are scarcely imbricate." — Hall, 1859. Remarks — The Missouri specimens have 3 or 4 plications on each side of the medial... | |
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