148 



ECHINODHKMATA. 



ORDER CYSTIDEA. 



The body, in this order, was enclosed in a box of calcareous 

 plates joined bj their edges. True arms were rarely present, and 

 smaller than in the Brachiata. The Cystideans are confined to 

 the Palaeozoic ages. They appear in the Cambrian and culminate 

 in the Lower Silurian. 



No. 463. Agelacrinus Cincinnatiensis, Roemer. 

 Cincinnati Group (Lower Silurian), Covington, Ky. 



No. 464. Caryocrinus ornatus, Say. 



Body, without column. In this genus all the 

 plates of the calyx are perforated with many 

 pores. This beautifully marked specimen is from 

 the Niagara Group (Upper Silurian), Lewiston, 

 N. Y. 



No. 465. [936, Cast]. 



Lepadocrinus (Apiocystites) G-ebhardi, 



[Conrad. 



This Cystidian has an oblong, oval body, compressed at the 

 sides, four unequal basal plates, four arms, and a column of 

 two distinct parts, — the upper being flexible, the lower, larger, 

 longer, and inflexible. This specimen, showing the body, 

 with a short stem, is from the Lower Helderberg (Upper 

 Silurian), Schoharie County, N. Y. 



