Palaeontographical Society Monographs Volume 7, Nos. 20-25

Palaeontographical Society Monographs Volume 7, Nos. 20-25

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1853 edition. Excerpt: ...horizontal lines of growth. Smaller valve slightly convex and depressed, the hinge-line forming an arch which merges imperceptibly into the lateral margins. Structure calcareo-corneous, with a distinctly punctured structure arranged in tubular layers; surface smooth, but presenting numerous lines of growth, and scattered or closely packed, slender, hollow spines, dilated at their base, and somewhat quincuncially arranged; no calcified supports for the arms. Muscular impressions unknown. 06.9. One of the species composing this remarkable genus was noticed in 1829,1 but it was only in 1845,2 that M. de Verneuil established the genus Sc;/lonotreta, which has been recognised and adopted by all subsequent naturalists, on account of the clearly defined characters which separate it both from Crania and Terebratula, where it had been located, as well as from all the other genera. _ Subsequent and most valuable information was thrown on the subject by the memoir of Dr. Kutorgaf' in which beautiful illustrations and structural details had been delineated with the greatest care. Mr. Morris, who first determined its occurrence in England, (from a specimen in the cabinet of John Gray, Esq., of Dudley, ) has likewise added some details.' M. de Verneuil pointed out that Siplzonotreta should be placed near Lingula and Discirza, but it is distinguished from the first by the pedicle not passing between the beaks, and from the second by the form of the perforated valve. I differ, however, from my learned friend in his belief that the perforated beak of Stp/wnotreta corresponds to the imperforate one of Terebratula. Mr. Morris considers the genus allied to Crania; and Professor King places it in his family Craniadce. Professor Forbes more

Product details

  • Paperback | 172 pages
  • 189 x 246 x 9mm | 318g
  • United States
  • English
  • black & white illustrations
  • 1236877691
  • 9781236877697