202 PROCEEDINGS OF THE ACADEMY OP [1886. 



CALCEOCKINUS Hall (Revised by W. and Sp.). 



1851. Hall, Geol. Rep. N. York, vol. ii, p. 353, PI. 85, figs. 5, 6. 



18(16. Shuraard, Trans. Acad. Sci. St. Louis, vol. ii, p. 358. 



1869. Meek and Worthen, Proc. Acad. Nat. Sci. Phila., p. 73. 



1873. Meek and Worthen, Geol. Rep. Illinois, vol. v, pp. 443 and 502. 



1877. S. A. Miller, Cat. Amer. Palajoz. Fossils, p. 73. 



1879. Hall, 28th Rep. N. York St. Cab. Nat. Hist. (Ed. ii), p. 146. 



1882. De Loriol, Palseont. Francaise, Tome xi (Crinoides), p. 51. 



1883. Ringueberg, Journ. Cincin. Soc. Nat. Hist., p. 130. 



Syn. Gheirocrinus Hall (not Eicliwald, 18")6); Hall, 1860, I'^th Rep. 

 N. York St. Cab. Nat. Hist., p. 123 ; Salter, 1859, Murch. Siluria 

 (Ed. 3), p. 535 (Catalogue name); Hall, 1862, 15th Rep. N. Y. St. 

 Cab. Nat. Hist., p. 166 ; Zittel, 1879, Handb. d. Palaeout., i, p. 358. 



Syn. Chirocrinus, Angelin, 1878, Icon. Crin. Suec, p. 22. 



Syn. Pendulocrinus, Austin MS. (Salter, Siluria, p. 535). 



Syn. Eucheirocrmus, Meek and Woithen, Geol. Rep. 111., v, p. 443. 



In general form the specimens resemble a wilted flower, owing 

 to the position of the cal3'x, which hangs downward along the 

 column. The calyx is laterally compressed, especially at the 

 juncture of basals and radials, where it is almost linear ; while a 

 transverse section across the median part of the radials and 

 through the centre of the basal disk is decidedly triangular. 

 The anterior side forms a flat body, broadly truncate at the lower 

 end, constricted in the middle, and composed exclusively of the 

 radial plates. The basals, which are placed upon the posterior 

 side, are separated from the radials of the opposite side by a 

 widely gaping articular line, occupying the lower end of the 

 calyx. Along this line, probablj^ the upper part of the Crinoid 

 could be bent upwards and be brought in an erect position. The 

 posterior side is composed, in addition to the basals, of two non- 

 arm-bearing plates, which face laterally the incurving sides of the 

 radials, and support upon their upper side an extremely large 

 ventral tube. 



The basals jointly form a kind of semicircular disk, of which 

 the straight line faces the truncated lower side of the anterior 

 radial, and the curved part rests against the infolding lateral 

 margins of the lateral radials, and against the two non-arm- 

 bearing plates. The basal disk, which is slightly convex, is com- 

 posed of three pieces, two of which are equal, the other large and 

 of a very different shape. The two former taken together are 

 lunate, and enclose within their arched sides the other plate, 

 which lies transversely, and occupies almost the entire width of 



