. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 518 Dr. H. A. Nicholson and Mr. A. H. Foovd on a XLIX.— On a new Genus of Devonian Corals, with De- scriptions of some Species of the same. By H. Alletne Nicholson, , , Regius Professor of Natural History in the University of Aberdeen ; and Arthur H. FOORD, , late of the Geological Survey of Canada. [Plate XVII.] [Contiuued from p. 400.] RhapMdopora stromatoporoides (continued). We are, however, entirely satisfied that the appearances just described, upon which S
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 518 Dr. H. A. Nicholson and Mr. A. H. Foovd on a XLIX.— On a new Genus of Devonian Corals, with De- scriptions of some Species of the same. By H. Alletne Nicholson, , , Regius Professor of Natural History in the University of Aberdeen ; and Arthur H. FOORD, , late of the Geological Survey of Canada. [Plate XVII.] [Contiuued from p. 400.] RhapMdopora stromatoporoides (continued). We are, however, entirely satisfied that the appearances just described, upon which Schllxter founded his PacJiytlieca steUtmicans, are of purely inorganic origin, and are the result of mineralization. They are probably due to a finely fibrous crystallization of the calcite, which has caused the dark-coloured impurities in the matrix to arrange themselves in conformity with the crystalline fibres. The radiating fibres thus produced frequently extend from one tube to another, cutting through the walls of the corallites, and so producing the beautiful starry appearance which characterizes tangential sections, and upon which Prof. Schlilter based his name of " sfeUimicans "?^. This process of mineralization was potent enough to effect the almost complete destruction of the tabulte, and in large part that of the walls of the corallites as well, the latter remaining in parts only obscurely discernible. Here and there this pro- cess was not quite complete, and hence we sometimes find spots in most vertical sections (PI. XVI. figs. 1 c and 7) in which the visceral chambers have not been wholly occupied by this infiltrated material, but have been partially filled with clear calcite, and have the tabulee still left. Moreover, by the extension of the radiating crystalline fibres from each centre of crystallization through the walls of the corallites into con- tiguous tubes were produced those curious dark transverse bavs seen in tangential sections intersecti
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