552 PALAEONTOLOGY OF ILLINOIS. 



as well as can be seen from the crushed condition of the 

 specimen. Eirst radials larger than the subradials, wider 

 than high, except the one on the right of the anal plates, 

 which is smaller and nearly quadrangular in outline, the 

 others are pentagonal. Second radials a little higher than 

 wide, constricted about their middle, and produced into a 

 salient angle above. Arms two to each ray, as far as can 

 be seen in the specimen before us, composed of alternating 

 wedge-shaped pieees, having their thickest margins pro- 

 duced into little nodes. The arms bifurcate on the tenth 

 or twelfth plate above the second radials, continuing thence 

 single to their extremities. Pinnule are thrown off from 

 the inner side of the arms on alternate plates, composed of 

 long slender joints. 



Locality and position Chester disvision of the Lower Carboniferous, 

 Chester, Illinois. 



GENUS O^YOHOOEI^US. 

 ONYCHOCBINUS WHITFIELDI, Hall (sp.) 



PI. 20, Fi 3. 

 Forbesiocrinus Whitfieldi, HALL, 1858. Iowa Report, p. 632. (See 111. Report, Vol. n, p. 243.) 



BODY sub-discoidal, the raj^s extending, out nearly hori- 

 zontally. Basal pieces very small, or merely resembling a 

 somewhat thickened terminal joint of the column. Sub- 

 radial pieces comparatively large, all, excepting the hex- 

 agonal one on the anal side, having a general pentagonal 

 form, though two or three of the others have the upper 

 salient angle slightly truncated, so as to give them an 

 additional angle. First radial plates a little larger than 

 the sub-radials, about twice as wide as long, pentagonal 

 and hexagonal. Second and third radials as w T ide as the 

 first, or a little wider, but generally slightly shorter, all, 

 excepting those on the rnal side, hexagonal, the latter 

 having the end next the anal series truncated, so as to 



