. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. B D In some Mesozoic and recent forms and in fossil crinoids such as Onychocrinus and Apiocrinus (figure 27 C, D) the top columnal remains permanently attached to the calyx, and the new nodal joints are formed beneath. The name proximate has been given to this fixed columnal (Bather, 1900, p. Figure 27 Some types of columns. A, diagram of column of Gastrocrinus patulus, the latest formed columnals numbered 1, the oldest 6; 5 and 6 bear cirri. B, quinquepartite column of Pentacrinus basalti- f or mi
. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. B D In some Mesozoic and recent forms and in fossil crinoids such as Onychocrinus and Apiocrinus (figure 27 C, D) the top columnal remains permanently attached to the calyx, and the new nodal joints are formed beneath. The name proximate has been given to this fixed columnal (Bather, 1900, p. Figure 27 Some types of columns. A, diagram of column of Gastrocrinus patulus, the latest formed columnals numbered 1, the oldest 6; 5 and 6 bear cirri. B, quinquepartite column of Pentacrinus basalti- f or mis. C, proximal end of column of Onycho- Io8)- 1 he UltemodeS lengthen crinus, showing enlargement of column and infrabasals, ryrOCeedinQ' distad ' that is the IB, fused to the top columnal, the proximale, P. D, cup and part of the column of Apiocrinus elegans, Column matured from the TOOt showing proximale, P, and other enlarged columnals. ,-, • 1 . • 1 • B, basals; R, radials. (A, D, after Bather, 1900; B, after UP' the Primal portion being Springer in Zittel, 1913; C, after Wachsmuth and permanently in a State of Springer, 1897) . immaturity. borne columns (Platycrinus) show no internodals; in others, the internodes begin at quite a distance from the calyx (figure 27C; plates 38, 39). Just as in the case of the arms, the column is pierced by a longitudinal, usually central, canal, the axial canal, which is circular, oval or pentagonal in cross section. There is a remarkable variation in the size of the axial 1 Springer (1920, p. 29) believes that the view (expressed by Wachsmuth and Springer, 1897, pp. 39. 40) that in the Flexibilia the topmost columnal was persistently fused with the infrabasals is more theoretical than practical. It is doubtless true that such a fusion often occurred in adult specimens in which stem growth was completed, but the often persistent attachment of the proximal ossicles to the infrabasals can readily be accounted for by close Pleas
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpaleont, bookyear1923
