Proceedings of the Academy of Natural Sciences of Philadelphia (Volume 117-118)

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. 1882. Excerpt: ... inner divisions of the ray, which give off exclusively the branches, with the double-jointed brachial extensions in the ray of M. pachidactyl us, and the outer arms of the former with the branchlets of the latter. Zittel takes Mariacrinus Hall to be a synonym of Ctenocrinus Bronn, which we refer to Melocrinus, following Schultze. Hall's M. macropetalus will be arranged under Corymbocrinus Angelin, and among the Calyptocrinidse. Its arms are yet unknown, but the arrangement of its plates agrees perfectly with that genus. Mariacrinus stoloniferus Hall is described only from fragmentary columns. Amended Diagnosis.--Form of calyx obconical; general aspect and surface ornamentation similar to Glyptncrinus; radiating strise passing from plate to plate; radials all along their median line elevated into high rounded ridges, somewhat resembling recumbent arms; interradial and interaxillary arese large and depressed. Basals four, small, almost of equal size, the one facing the anal area largest. Primary radials 3 X 5, nearly as wide as high, decreasing in size upwards; the first set joining laterally; the second enclosing the first anal and first interradial plates; the third supporting 3X 10 secondary radials, which are generally of uniform size and vertically separated by six or more interaxillary plates. The secondary radials are followed by several tertiary radials, which vary in number with the age of the individual--mature specimens having live and even more--all placed in a direct line with the arms and somewhat resembling arm plates. Arms four to each ray, the inner ones branching, but rarely more than once or twice, the outer arms remaining simple throughout, and taking a somewhat lateral course. The inner arms are placed close together, almost parallel wi...