780 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



rather long quadrangular pieces. Pinnules long. Anal plate in size and 

 form resembling the radials. Anus and ventral disk not visible in the 

 specimens. 



Column near the calyx straight, but at 5 mm. from the calyx it curves 

 abruptly back upon the crown, then it enlarges, and by a reverse curve coils 

 upon itself and the included calyx and arms, giving off from alternate joints 

 at the concave side two rows of long cirri, which sometimes completely 

 envelope and conceal the crown. Near the calyx, the stem joints are short 

 and circular, but they gradually grow longer and crescent-shaped, their 

 width increasing from 2 to 3 mm. The cirri are very long and stout at their 

 proximal ends, but terminate in a sharp point. They are composed of about 

 sixteen to eighteen joints, which are as wide as long, and ratliate from the 

 centre of the spiral curvature of the stem. 



Horizon and Locality. — Keokuk group ; Indian creek, Montgomery 

 Co., Ind. 



TyjKs in the collection of Wachsmuth and Springer. 



Camptocrinus cirrifer W. and Sp. (hot. spec). 

 Plate LXXVI. Figs. 13a, h, c. 



In its general aspect closely resembling the preceding species, the calyx, 

 however, shorter, especially the basal part, which occupies only one third 

 the length of the dorsal cup, being but shghtly convex at the bottom, and 

 rather deeply depressed in the centre for the reception of the column. Radi- 

 als once and a half as long as wide, the sides nearly parallel, the upper faces 

 slightly excavated to one half their width. Costals two, very short, the 

 intervening suture lines obscure ; the first linear, the second subtrigonal, its 

 sloping upper faces at right angles. Arms two to the ray, simple, slender, 

 divergent, thread-like in the upper portions, and composed of long, quadran- 

 gular joints. Pinnules of moderate length and not in contact. All plates 

 perfectly smooth. Structure of ventral disk and anus unknown. 



The column is narrow in the upper portions, but gradually increases in 

 width downward, until at an inch and a half from the basals it is twice as 

 wide as at the top. Close to the calyx it bends abruptly upward to a level 

 with the top of the radials, then reversing it curves downward, either gently 

 to the end, or — more generally — forming a coil around the crown. The 

 stem joints are short and circular near the calyx, but soon grow longer, and 

 the section becomes oval and gradually crescent-shaped with the concave 



