Maryland Geological Survey: Upper Cretaceous. 2 pts

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Johns Hopkins Press, 1916
 

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Página 540 - Along the ventral margin the edge is folded into sharply angular teeth which do not extend as plications into the body of the shell, these toothlike crenulations becoming smaller and at last disappearing upon the lateral margins of the shell. Lower valve not known. Remarks. — It is with some hesitation that a species of so variable a group of shells as the oysters has been proposed for a single specimen, but it has not been possible to identify it with any of the described forms, and it seems to...
Página 38 - York, 1818. 1820 HAYDEN, HH Geological Essays ; or an Inquiry into some of the Geological Phenomena to be found in various parts of America and elsewhere.
Página 188 - Geological notes on the Noursoak peninsula, Disco island, and the country in the vicinity of Disco bay, North Greenland, 55.
Página 42 - TYSON, PHILIP T. Second Report of Philip T. Tyson, State Agricultural Chemist, to the House of Delegates of Maryland, Jan.
Página 535 - ... the anterior hinge extremity decreasing regularly in size; along the upper or concave margin the shell is marked by a series of short, marginal plications. Lower valve moderately convex, with a small scar of attachment; upper valve much flatter, its plications similar to those of the lower valve.
Página 435 - SGS, vol. 1 8), p. 36, pi. 2, figs. 8-9, not fig. 10. (Not P. octolirata Conrad.) Description. — Shell small, subglobular or subpyriform in form, with about three, ventricose, rapidly expanding volutions; the dimensions of a nearly complete internal cast being: height, 19.5 mm., which might be increased to 25 mm. if the anterior canal were complete; maximum diameter, 16 mm.; height of spire, 5.5 mm. Spire low-conical, volutions distinctly flattened adjacent to the suture, marked by from six to...
Página 366 - The lower distal angle is acute, and there is an oblique groove and a short keel bordered with small tubercles near it on the outer face. The upper proximal angle is produced backward. The inner face has a small distal group of tubercles and some scattered pustules, both usually almost effaced. Merus subtriangular in section, the upper keel strongly arched, lower keel nearly straight and more strongly serrate, the middle of the very convex outer surface granulose, with two rounded tubercles at the...
Página 549 - ... curve to the upper posterior margin of the shell. Upper or right valve operculiform, roughly ovate in outline and inclosed within the projecting margin of the lower valve; usually distinctly concave on outer surface and convex on inner surface; hinge and other internal characters essentially the same as in Exogyra costata Say; beak depressed, not prominent, with nearly flat spiral twist or coil ; surface ornamented with numerous concentrically arranged sharp-edged lamellae, separated by deep...
Página 410 - Shell elongate, fusiform ; whorls cancellated by longitudinal and revolving ribs ; columella with one very oblique fold, and sometimes one or more smaller secondary folds. In shape this genus is not unlike the two preceding genera [ Volutoderma Gabb, and Fulgoraria Schum], but it differs from them all in having essentially a single large oblique fold.

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