488 PALAEONTOLOGY OF ILLINOIS. 



thick, and strongly convex, slightly higher than wide, four 

 hexagonal and one apparently heptagoiial. First radial 

 plates about the size of the subradials, having a general 

 pentagonal outline, with the two superior lateral angles 

 more or less truncated apparently by the first vault pieces; 

 not tumid like the subradials; each with a moderately con- 

 cave, outward-sloping facet, for the reception of the next 

 range of radials. Succeeding primary radial pieces (of 

 which one ray shows two and another three) about half as 

 wide as the first radials; all rounded on the back, two in 

 one ray and one in another, transversely oblong ; the last 

 one in each of these rays proportionally a little larger 

 than the others, pentagonal in form, and supporting on 

 its superior sloping sides the arms, which, in the anterior 

 ray, bifurcate again on the second piece, beyond which the 

 arms, in the typical specimen, can be traced a short dis- 

 tance without showing further bifurcation. (Number and 

 arrangement of the anal series unknown.) 



Breadth of body (allowing for compression), about 1.40 

 inches; hight to top of first radials, 1.10 inches. 



This species is somewhat similar in its general characters to such 

 forms as C. bulletins and C. protuberans, of Hall, (Iowa Keport, pp. 624, 

 626,) but differs from both in having its basal pieces proportionally 

 much larger, narrower and proportionally longer. From C. protuberant 

 it also differs, in not having its first radial pieces tumid, while one of 

 its arms is seen to divide again on the third piece after the first division 

 on the third radial, instead of merely giving out small lateral branches, 

 as in that species. 



Our specimens being defective on the anal side, we are not quite sure 

 as to the nature of the anal parts, though there seems to have been, as 

 is usual in Barycrinus, only one anal piece between the first radials. 



Location and position Keokuk Limestone, of the Lower Carbonifer- 

 ous series, near Whitehall, Greene county. 



