Maryland Geological Survey: pt.1] Lower Devonian, textJohns Hopkins Press, 1913 |
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Maryland Geological Survey: pt.1] Lower Devonian, text Maryland Geological Survey Vista completa - 1913 |
Maryland Geological Survey: PT. 1] Lower Devonian, Text Maryland Geological Survey Sin vista previa disponible - 2015 |
Maryland Geological Survey: PT. 1] Lower Devonian, Text Maryland Geological Survey Sin vista previa disponible - 2015 |
Términos y frases comunes
Allegany County aperture beak beds brachiopods bryozoa cardinal Cash Valley Cherry Run chert Chonetes Chonetes jerseyensis Cobleskill Coeymans Collection.-Maryland Geological Survey Collection.-U. S. National Museum concave convex corallites Corriganville crinoids Cumberland Dalmanella Decker Ferry depressed Description Devil's Backbone Devonian diameter dorsal valve elevated fauna Favosites figs fossils Genus Geol gibbous Hall and Clarke Helderberg HELDERBERG FORMATION hinge-line Hist incurved KEYSER MEMBER Knobly Mountain lamellæ Length limestone lobe Lower Devonian Manlius Maryland Meristella mesial N. Y. State Cab N. Y. State Mus Occurrence.-HELDERBERG FORMATION Occurrence.-ORISKANY FORMATION Ohern Oriskany ORISKANY FORMATION Platyceras plications posterior prominent pygidium radiating Rept RIDGELY MEMBER Rondout rounded sandstone Schuchert Schuchertella SCOTLAND MEMBER shale shaly shell Shriver side Silurian sinus slightly species specimens Spirifer striæ Stromatopora Stropheodonta Surface marked Tentaculites Thin-bedded Tonoloway transverse U. S. National Museum Uncinulus upper ventral valve Weller West Virginia width York zone
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Página 228 - Ambulacra in mature specimens very prominent, triangular in transverse section, extending around the entire periphery of the theca and touching the column. In the second largest individual each ambulacrum had about 44 brachioles, in another mature but smaller specimen there were only 32. Brachioles unknown, apparently more slender than in P. gordoni. Ambulacral grooves narrow, and covered by highly elevated ambulacralia of about the same nature as in P. gordoni, but less numerous and the larger plates...
Página 224 - ... plates 14 and 15 is the largest, with about 120. Hydropore minute, closely adjoining the madreporite. Anal pyramid depressed, consisting of 7 somewhat ornamented plates surrounded by a circle of 8 larger plates of irregular size and definite sculpture.
Página 52 - Observations on the Geology of the United States of North America; with remarks on the probable effects that may be produced by the decomposition of the different classes of Rocks, on the nature and fertility of soils; applied to the different States of the Union, agreeably to the accompanying geological map.
Página 73 - The Oriskany equivalents are not present in southern Europe and if, as is probably true, this time is represented by faunas, they are very unlike the American development. Nor is the southern Oriskany life — the Camden of the Mississippian Sea — present in Europe, yet when the typical Oriskany and more especially the Gaspe faunas are compared with those of the Coblenzian of northern Europe, the faunal connections are at once convincing and indicate that migration between these areas took place...
Página 197 - Cell walls thin, but frequently much thickened near the surface by silification, and sometimes granulose or spinose on the inner face. On some specimens the cells, at the surface, are nearly equal, having a diameter of about 1.5 mm.; on other specimens the diameter varies from .66 mm. to 1.5 mm. On many specimens some of the cell tubes are larger and less angular than those surrounding them, being a little more than 2 mm. in diameter.
Página 197 - Corallum consisting of large, lenticular, depressed convex or hemispherical masses ; base covered by a strongly wrinkled epitheca. Cell tubes polygonal ; their inner surface showing evidence of a few strong longitudinal striae. Septa frequent, from ten to fifteen in the space of 10 mm. ; thickness equal to that of the cell walls. Mural pores in one or two ranges, comparatively large, circular, with margins distinctly elevated. Cell walls thin, but frequently much thickened near the surface by silification,...
Página 227 - Ambulacra well defined, flat topped, extending around the entire periphery of the theca and touching the column. Ambulacrals large. Each ambulacrum in full-grown specimens has about 36 brachioles ; in a small specimen having a thecal length of 15 mm., there are but 24 brachioles. Brachioles usually not preserved. Ambulacral groove wide, roofed by a median double row of tiny angular ambulacralia arranged in short crescents, and outside of these by a single row of much larger, strongly elevated plates,...
Página 56 - Palaeontology, vol. vi. Corals and Bryozoa. Text and plates, containing descriptions and figures of species from the Lower Helderberg, Upper Helderberg, and Hamilton groups.
Página 232 - ... occupied by a stout column. For general form, shape of individual plates and their ornamentation, see figures 1-3, plate xxxv, and text-figure 34. Ambulacra prominent, rounded, extending along three sides, bent around the excavated base of the theca, and touching the column. Each ambulacrum has on one side about 30 brachioles, or 60 to each ray, and about 180 on the entire theca. Brachioles apparently not very stout nor long, and composed of rather large pieces. Ambulacral grooves narrow, but...