ECHINODERMA TA—CRINOIDEA . 561 



LXIX. Crotalocrinus Austin. 

 Crown, when arms are closed, similar to an elongate bud; when 

 arms are opened, wheel-shaped, with five lanceolate areas between 

 the bases of the rays. Calyx subglobose, flattened above. IB 5, 

 large, uniform. B 5, extending three 

 fourths of the height of the calyx and sup- 

 porting the R and a small anal. Costals, 

 distichals, palmars and postpalmars rest 

 against one another and against the broad 

 upper face of the R. Arms long, branch- 

 ing frequently, the branches connected 

 laterally by points of attachment with open ^ig. 1897. Crotalocrinus, 



. . . . ^ analysis of calyx. (After 



Spaces between, hence formmg a sort of ^ ^ j. n 



network around the calyx. Tegmen flat, 



on a level with the spreading arms. Anus excentric, at the end of 



a tube or a small protuberance (Fig. 1897). Siluric. 



188. C. americanus Weller. Siluric. 



Calyx one and one fourth inches in diameter. R ornamented 

 with very fine irregular papillae or wavy ridges. 



Niagaran of Illinois (Chicago area). 



LXX. Camarocrinus Hall. 



Pear-shaped, spheroidal or depressed spheroidal, chambered 

 bodies, composed of many small plates, and to one end of which are 

 attached roots and a short stalk of the same nature as those of 

 crinoids. No evidence of ambulacra, mouth or anus. Chambers 

 6 or 7, rarely 11, one large mediobasal chamber surrounded by the 

 others, the number of chambers usually indicated exteriorly by 

 constrictions over their walls. 



Nature of the fossil is problematical. Variously considered as 

 theca of cystoids or crinoids (disproved by absence of ambulacra, 

 mouth and anus), brood sacks or brood receptacles (at total dis- 

 agreement with breeding organs and habits of living crinoids), 

 degenerate crinoids (unsupported by the detailed structure of these 

 bulbs), or floats attached to the root of some unknown crinoid, 

 held together after the death of the animal by its firmly interlocked 

 walls, while the crown and stalk dropped away (Schuchert). 

 Siluric-Devonic. 

 36 



