FOSSILS OF THE CIIKSTEU GROUP. ,V>;5 



leave only five well defined uncles. Third radials of very 

 nearly the si/c of the first, all pentagonal, and supporting 

 on their superior sloping sides the secondary radials, upon 

 the second of which another bifurcation takes place, and 

 these divisions bifurcate again (at least in one instance) on 

 the third piece, at which point the arms appear to become 

 free. Interradial pieces ten to each space; iiiteraxillary 

 plates one to each space. Anal plates presenting the usual 

 narrow, finger-like appearance, two of them being seen in 

 place in the type specimen, the first resting upon the sub- 

 radial, and the second upon the first, while a few others 

 are seen ranged in the same line above, but somewhat dis- 

 placed. Surface apparently smooth. Column round, and 

 composed near the base of very thin pieces. 



Breadth of body to the second bifurcation of the rays, 

 including the iiiteraxillary pieces. 1.30 inches; hightof do., 

 exclusive of the vault, 0.48 inch. 



This species is probably most nearly allied to 0. Metki (=Forln'xi- 

 ocrinwi Jfeeki, Hall,) but lias the body rather more depressed, with 

 interradial spaces broader, and occupied by a greater number of pit 

 while its radial plates are proportionally narrower. It shows no little 

 accessory patelliform pieces between the radials as far out as they can 

 be traced in the type specimen, but they doubtless exist between the 

 arm pieces. 



Prof. HALL compares this species with Forbesiocrinus TVortheni, and 

 mentions some of the well defined differences, but appears to entirely 

 overlook the deeply excavated character of its anal space, occupied 

 only by a range of small pieces, resting, like a little arm. upon the sub- 

 radial, instead of having this space tilled with twenty or more plates, 

 like the interradial areas, as in F. Wortlteni. We have the type speci- 

 mens of both of these species before us. and that of the species under 

 consideration shows the little isolated range of anal pieces in the middle 

 of the anal area, very clearly, and it is evident they were not suspected 

 to be such by Prof. HALL, who says the anal plates are unknown, while 

 they are not illustrated in his diagram published in the Iowa Report. 

 In short, these two forms belong to the distinct genera or sub-genera 

 OityokocHntu and Forbefsiocrinus. 



Locality and 2><>#ition Opposite Kaskaskia. in Randolph county, Illi- 

 nois : from the Chester division of the Lower Carboniferous series. By 



