A Natural History of the Crinoidea, Or Lily-Shaped Animals; With Observations on the General Asteria Euryale, Comatula and Marsupites Illustr. with 50 Coloured Plates

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General Books, May 16, 2012 - 52 pages
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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. 1821 Excerpt: ...yet I thought it advisable to constitute the division SemiarTiculata, to mark in a more conspicuous manner the transition from regularly articulating joints to plates adhering only by muscular sutures. IV. GENUS POTERIOCRINITES. VASE-LIKE LILY.SHAPED ANIMAL. Generic Character. A Crinoidal animal, with a round column composed of numerous thin joints, having in their centre a round alimentary canal, and articulating by surfaces striated in radii. Round auxiliary side arms proceeding at irregular distances from the column. Pelvis formed of five pentagonal plate-like joints, supporting five hexagonal intercostal plate-like joints, and five plate-like scapulae, having on one of the intercostals an interscapulary plate interposed. An arm proceeding from each of the scapulae. Base, probably fascicular, and permanently adhering. Observation. The generic name is derived from norapioN, a drinking vessel, having been suggested by the resemblance of its figure to that of a common conical wine glass. This genus, as far as I have been able to ascertain, contains two species only, P. Crassus, and P. Tenuis; the former, as was observed, serves as a type for the generic character, the latter bears analogy to it in general formation, but from its plates only adhering by sutures, and not showing articulations, renders the transition to the division Inarticulata perfect. No recent individual belonging to this genus has been as yet discovered. It is with considerable hesitation that I describe these five plates as belonging to Ihe Pelvis, the analogy of their lower articulating surfaces, seems, perhaps, rather to indicate their belonging to the first costal series. I have never yet had an opportunity of seeing the connection of these plates with the first columnar joint fairly ...

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