. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. 140 HISTORICAL PALAEONTOLOGY. Devonian age; and the whole of this group has become ex- tinguished—unless we refer here the still surviving Z^/r/jw/^;//^.. Fig. -]().—a. Part of the under surface of Stromatopo7-a tuberculnta, showing the •wrinkled basement membrane and the openings of water-canals, of the natural size; b. Portion of the upper surface of the same, enlarged ; c, Vertical section of a fragment, mag- nified to show the internal structure. Co
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. 140 HISTORICAL PALAEONTOLOGY. Devonian age; and the whole of this group has become ex- tinguished—unless we refer here the still surviving Z^/r/jw/^;//^.. Fig. -]().—a. Part of the under surface of Stromatopo7-a tuberculnta, showing the •wrinkled basement membrane and the openings of water-canals, of the natural size; b. Portion of the upper surface of the same, enlarged ; c, Vertical section of a fragment, mag- nified to show the internal structure. Corniferous Limestone, Canada. (Original.) The Coilenterates^ however, are represented by a vast number of Corals, of beautiful forms and very varied types. llie marbles of Devonshire, the Devonian limestones of the Eifel and of France, and the calcareous strata of the Corniferous and Hamilton groups of America, are often replete with the skeletons of these organisms—so much so as to sometimes entitle the rock to be considered as representing an ancient coral-reef. In some instances the Corals have preserved their primitive calcareous composition j and if they are embedded in soft shales, they may weather out of the rock in almost all their original perfection. In other cases, as in the marbles of Devonshire, the matrix is so compact and crystalline that the included corals can only be satisfactorily studied by means of polished sections. In other cases, again, the corals have been more or less completely converted into flint, as in the Cornifer- ous limestone of North America. When this is the case, they often come, by the action of the weather, to stand out from. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Nicholson, Henry Alleyne, 1844-1899. Edinburgh, London, Blackwood
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Keywords: ., bookaut, bookcentury1800, bookdecade1870, booksubjectpaleontology
