New Species of Crinoids from Illinois and Other States

New Species of Crinoids from Illinois and Other States

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ...after having examined definitions and illustrations of all the species found in this country, that have been refewed to Graphiocrinus, by different authors, we are fully convinced that the genus has not been found in America. When Prof. James Hall founded the genus Scaphiocrinus, in the Geology of Iowa, Vol. I, p. 55l, and described the type, Scaphiocrinus simplex, he very clearly distinguished it from Graphiocrinus. The species here described is distinguished from Scaphiocrinus simplex, by having twelve arms instead of ten, which is a good specific distinction but not of generic importance. It is distinguished again from S. simplex, which has six azygous plates or more, that rise above the calyx, by having only one azygous plate confined between the plates of the calyx. This may be of generic importance, but we are not willing to found a new genus upon differences of doubtful importance, when they are known to belong to only a single species. In each case the first azygous plate truncates a subradial and the difference consists, in the additional plates, that separate the second radials and first arm plates, in one species, that do not exist in the other. We prefer, at present, to regard this as of specific importance only. The distinction made by Prof. Hall between Scaphiocrinus and Poteriocrinus is a good one and all the species he referred to Scaphiocrinus properly belong there, as well as some that others have defined. None of them belong to Graphiocrinus. Found in the Kinderhook Group, at LeGrand, Iowa, and now in the collection of Wm. F. E. Gurley. Family AGASSIZOCEINIBE. AGASSIZOCRINUS OVALIS, n. Sp. Plate II, Fig. i3, an entire specimen viewed opposite to azygous area; Fig. i4, azygous side, of another calyx. Species large, contracted at...show more

Product details

  • 12-17
  • Paperback | 24 pages
  • 189 x 246 x 1mm | 64g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236610431
  • 9781236610430