49C PALAEONTOLOGY OF ILLINOIS. 



posed of wedge-shaped pieces, the first one in each ray 

 being about twice as long as those above. 



This species is nearly allied to S. decadactylus, Meek and Worthen, in 

 Vol. II, of the 111. Geol. Survey, p. 238, PI. 17, Fig. 3, but differs from 

 that species in the relative size and form of the body plates, and the 

 size and structure of the arms. - 



Dedicated to the Hon. WILLIAM McADAMS, of Otterville, in Jersey 

 county, from whom we received the typical specimen, and to whom we 

 are indebted for many fine specimens from the same horizon in Jersey 

 county. 



Locality and position Keokuk Limestone, Otter creek, Jersey county, 

 Illinois. 



EORBESIOCROTUS WOKTHEKI, Hall. 



PL 14, Fig. 2, and PL 15, Fig, 7. 



Forbeeiocrinus Wortheni, HALL, 1858. Iowa Geol. Report, Vol. I, Part II, p. 632, PL XVII, Fig. 5. 

 Supplement to same, (1860) PL 3, Fig. 7. 



BODY attaining a moderately large size, subhemispheri- 

 cal in form, when the arms are broken away, but when 

 they are attached and incurved, the whole presenting a 

 nearly subglobose general outline.* Basal plates extremely 

 short, or only appearing externally like a slightly thickened 

 upper joint of the column. Subradial pieces comparatively 

 small, four of them presenting a general subtrigonal out- 

 line, w r ith the lateral attenuated angles slightly truncated 

 and the upper sides sloping so as to allow the first radi- 

 als to come down at the middle nearly to the base; fifth 

 subradial much wider than the others, though scarcely as 

 long, being about three times as wide as long, and appa- 

 rently irregularly pentagonal in form. First radial pieces 

 larger than the subradials, w r ider than long, and generally 

 heptagonal in form. Second and third radials usually 

 somewhat smaller than the first, wider than long, and hex- 

 agonal in outline. Fourth radials of near the same size as 

 the others, pentagonal or hexagonal in form, and support- 

 ing on each of their superior sloping sides, in direct suc- 



* Prof. HALL describes the body as being " somewhat discoid." This, however, is only the case in 

 accidentally compressed specimens. 



