. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. 3. (figure 25) where the arm branches are united by lateral processes to form a flexible network which may be divided into five broad, reticulate, fanlike fronds or may be continuous all around the crown; like M e 1 o - crinus in which the two main uniserial rami in each ray are fused for some distance or to their full extent by their inner margins, giving to the crown five compound main arms or radial appendages bearing pinnulate armlets or ramules at intervals from opposite plates in the ray and
. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. 3. (figure 25) where the arm branches are united by lateral processes to form a flexible network which may be divided into five broad, reticulate, fanlike fronds or may be continuous all around the crown; like M e 1 o - crinus in which the two main uniserial rami in each ray are fused for some distance or to their full extent by their inner margins, giving to the crown five compound main arms or radial appendages bearing pinnulate armlets or ramules at intervals from opposite plates in the ray and from one side only of each half (plates 6, 8, 12, 13, 15, 16). When an immovable sutural union occurs between two brachials of a pinnu- late arm, of which only the upper one is pinnule-bearing, the union is known as a syzygy. The lower brachial without apinnule is termed a hypozygal, the Figure 25 Crotaiocrinus puicher. upper pinnule-bearing brachial is the A, calyx and arms cut across to show how the arms are rolled up. x 2/3. B, cross ^P'l^ygdL. section of four contiguous arm-ossicles of the By the fusion Qf the right and left net-work. C, dorsal aspect of arm-plates, showing their intimate union; those above Ossicles of a biserial arm a Compound the two rows figured have been broken away -u 1 â 1 â r j-u ⢠x. â 1 ,, .;, , . ⢠brachial is formed bearing two pinnules, so as to expose the side pieces and covering & ^ plates of the ambuiacrai furrows. (After one on each side. This process may be Springer in Zittel, 1913) . carried still farther, and by the fusion of two or three two-pinnulid brachials a compound brachial may be formed with two or three pinnules on each side. Certain genera, as Cordylo- crinus (p. 275), Clarkeocrinus (p. 180) and Liparocrinus (p. 397), have been studied in which are found two-pinnulid brachials (or fusions of two-pinnulid brachials) throughout the arms with no indication of previous biseriality. c Column The entire column or stalk of
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpaleont, bookyear1923
