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Página 128 - The Geology of Pennsylvania. A Government survey, with a general view of the Geology of the United States, Essays on the Coal Formation and its Fossils, and a description of the Coal Fields of North America and Great Britain.
Página 287 - There was nothing to indicate that the different objects in the roof-breccia were other than of contemporaneous origin. Subsequently a great physical alteration in the contour, altering the flow of superficial water, and of the subterranean springs, changed all the conditions previously existing, and emptied out the whole, of the loose incoherent contents, leaving only the portions agglutinated to the roof. The wreck of these ejecta was visible in the patches of "cinere impastate," containing fossil...
Página 195 - Agassiz maintains, substantially, that each species originated where it now occurs, probably in as great a number of individuals occupying as large an area, and generally the same area, or the same discontinuous areas, as at the present time.
Página 158 - The Birds | of | North America ; | the descriptions of species based chiefly on the collections | in the | Museum of the Smithsonian Institution.
Página 108 - I was struck with the similarity of these bead-like strings to the fibrillae of the muscle, and upon close comparison I found that the former were exactly of the same size, and had the same optical properties as the latter. Some of these appeared to be attached to the ends of the flat, ribbon-like fibres, and others at times loosened themselves and swam away. I was immediately impressed with the daring thought, that these Vibrios were the...
Página 198 - Calamus, — besides an elm and a Ceanothus doubtfully referable to existing species, — on the Mississippi, near Columbus, Kentucky, in beds which Mr. Lesquereux regards as anterior to the drift. Professor DD Owen has indicated their position " as about 120 feet lower than the ferrugineous sand in which the bones of the Megalonyx Jeffersonii were found.
Página 303 - Geology, &c. 24 pp. 8vo, •with 4 progress maps. — This is the annual report showing the progress made in the several important scientific trusts comprised in the Jermyn St. establishment now under the general direction of Sir RI Murchison. 8. Experimental Researches relative to Corroval and Vao ; two new varieties of Woorara, the South American Arrow-Poison ; by WILLIAM A.
Página 85 - The great beneficent law regulating these absorptions appears to admit of the following expression : those bodies which are most rare and precious to the growing plant are by the soil converted into, and retained in, a condition riot of absolute, but of relative insolubility, and are kept available to the plant by the continual circulation in the soil of the more abundant saline matters.
Página 154 - Aurelia flavidula, our common jelly-fish, I observed that the whole component mass of cells was in violent agitation, each cell dancing zigzag about •within the plane of the wall. If any one will shake about a single layer of shot in a flat pan he can obtain an approximate idea of the appearance of this moving mass. In a perfectly healthy condition these cells lie closely side by side, and do not move individually from place to place, but yet are active on one side, which constitutes the surface...