The Echinoderma, by F.A.Bather

The Echinoderma, by F.A.Bather

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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. 1900 edition. Excerpt: ... perhaps led on to Periechocrinidae, and so to Actinocrinoidea. The important ancestral family, however, is the Silurian Carpocrinidae, in which Acacocrinus is nearest to the Inadunate type. From them arose Barrandeocrinus with its recumbent arms, then the Coeliocrinidae without anal tube or respiratory pores, and, later on, the Batocrinidae possessed of both those structures. No members of this order survived the Lower Carboniferous, but during their history they developed some of the most numerous in individuals and species among crinoid genera, and in Barrandeocrinus, Eucalyptocrinus, Aganlcocrinus, and Strotocrinus, some of the most remarkable of all Echinoderma. SUB-ORDER. 1. Melocrinoidea. Monocyclica Camerata with RR in contact all round; IBr1 usually quadrangular. FAMILY 1. Gnrrrocarmnas. Melocrinoidea with 5 BB; in each half ray 2-8 m-, sometimes IIlBr; free arms rarely branch beyond IIIBr, and may be uniserial, zigzag, or biserial; iBr numerous but definite; iIIBr numerous, less definite; a ridge of anals in post. IR; tegmen of numerous small plates; stem round, with pentagonal lumen. All Ordovician of N. America, European representatives doubtful. Genera--Glyptocrinus, Hall (1847; W. & Sp., 1897; synn. Canistrocrinus, W. & Sp.; Pycnocrinua, S. A. Miller), has small BB and arms in zigzag (Fig.XXV.). Schizocrinus, Hall (1847; W. & Sp., 1881; (7) syn. Scyphominus, Hall non Zenker), doubtful, but close to Glyptocrinus, arms uniserial. Pen'glyptocrinus, W. & Sp. (1897), has large BB and biserial arms. FAMILY 2. Ms: I.oCRINIDAE. Melocrinoidea with 4 BB; in each half-ray 2-5 IIBr; these support 2 or 4 main rami giving off pinnules or pinnulate ramuli; iBr, iIIBr, and post. IR as in Glyptocrinidae; tegmen of numerous, .show more

Product details

  • Paperback | 122 pages
  • 189 x 246 x 7mm | 231g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236939115
  • 9781236939111