1886.] NATURAL SCIENCK8 OF PHILADELPHIA. 205 



nally arranged and form the exterior side of an enormous anal 

 tube, extending to the tips of the arms and perhaps beyond their 

 limits, with scarcely an}'^ diminution in size. Like in Calillocrinns, 

 only the posterior side of the tube is heavily plated, the anterior 

 side being composed of very small and delicate plates. 



The column is comparatively large, near the calyx composed 

 alternately of shorter and longer segments, which soon turn alto- 

 gether into long joints. Hall gives the column as very short; it 

 was, however, of considerable length in some cases, as we have 

 followed it up to a foot or more without reaching the root. 



Geological' Position, etc. Calceocrinus makes its appearance in 

 the Lower Silurian, but only in America. It struggled through 

 the Devonian, and reached its greatest distribution in the earlier 

 periods of the Subcarboniferous, but without flourishing abun- 

 dantly. Throughout this long period of time, the species change 

 but little, less than those of an}' other genus, and it is exceedingly 

 difficult to point out specific differences, which in most of them 

 are so slight that they hardly deserve the name. In Europe it 

 has been found only in the Upper Silurian. 



We recognize only the following species : 



188.3. Calceocrinus Barrandii Walcott, 35th Rep. N. Y. St. Mus. Nat. Hist. (Author's 

 Edit., p. 6), PI. 17, figs. 1, 2. Upper part of Trenton limest. Trenton Palls, 

 New Yurk. 



1865. C. Barrisi Worthen, Geol. Rep. Illinois, iv, p. 510, with woodcut. Hamilton 



group. Near Davenport, Iowa. 



]Sfi9. C. Bradley! Meek and Worthen, Proceed. Acad. Nat. Sci. Phila., p. 7?>; also 

 1873, Geol. Rep. III., vol. v, p. 502, PI. 14, fig 9. Keokuk limestone. 

 Crawfordsville, Indiana. 



1860. C. chrysalis Hall (Cheirocrinus chrysali's). Tj'pe of the genus. 13th Rep. New 

 York State Cab. Nat. Hist., p. 123, with diagrams. Shumard, 1866, Calceo- 

 crinus chrysalis, Trans. Acad. Sci. St. Louis, vol. ii,- p. 358. Niagara 

 group. State of New York. 



l862. C. clarus Hall (Cheirocrinus clarus), 15th Rep. New York State Cab. Nat. 

 Hist., p. 116, PI. 1, fig. 17. Shumard, 1866, Calceocrinus clarus, Tran.-s. 

 Acad. Sci. St. Louis, vol. ii, p. 358. Zittel, 1879, Handb. der Palajont., i, p. 

 358, figs. 2, 4, 5 a. Hamilton group. Ontario Co., N. Y. 



1878. C. gotlandicus Angelin (Chirocrinus gotlandicus), Iconogr. Crin. Suec, p. 

 22, PI. 16, figs. 6-14. Zittel, 1879, Handb. der Palfeont., i, p. 358, figs. 245, 

 b, c, d. Upper Silurian. Gothland, Sweden. 



1859, C. inaequalis Billings (Heterocrinus inaequalis), Geol. Surv. Canada, De- 

 cade iv, p. 51, PI. 4, fig. 7 f! ; Wachs. and Spr. Revision i, p. 70. Trenton 

 limestone. Ottawa. 



1866. C. perplexus Shumard, Trans. Nat. Sci. St. Louis, vol. ii. p. 358. Keokuk 



limest. Button-mould-Knob, Ky. 



