Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76 Under the Command of Captain George S. Nares and the Late Captain Frank Tourle Thomson Volume 5, V. 3

Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76 Under the Command of Captain George S. Nares and the Late Captain Frank Tourle Thomson Volume 5, V. 3

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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. 1881 edition. Excerpt: ...by Mr E. A. Smith in Ann. and Mag. Nat. Hist., 1878, vol. i. p. 67. From the species of Linthia, combining many of the characters of Schizaster, there is on the one hand but a step to species which have been associated with Prenaster, leading to Pe)icosmus, and which in their turn lead most naturally to Macropneustes, and of such types as Brissomorpha of Laube, in which the peripetalous fasciole has completely disappeared; while in another direction the structure of these species would also indicate affinities to such genera as Faorina, which in their turn lead to such genera as Gyclaster, to which many fossil species are frequently referred without reference to the presence or absence of a peripetalous fasciole. We have not as yet sufficient data, for the study of the young Schizaster, to enter into very detailed comparisons, but the following points are interesting as throwing additional light on the affinities of the genera allied to the Schizasteridae: --The limits which have been assigned to the genera closely allied to Schizaster are very unsatisfactory, and the generic characters by which different species are assigned to these genera or sub-genera pass so gradually one into the other, not merely among the recent species, but especially when we come to include the fossil species, that the task of properly limiting them appears hopeless, although these characters are convenient as subdivisions according to which we may associate groups of species. Take, for instance, species like Schizaster canaliferus, with a broad, deep sunken anterior ambulacrum, a short posterior lateral pair of ambulacra, and a well-developed lateral fasciole extending under the anal system, and they seem to form a well-marked group when contrasted to species like..show more

Product details

  • Paperback | 196 pages
  • 189 x 246 x 11mm | 358g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236538900
  • 9781236538901