294 New Species of Orinoidea from the 



tagonal. First radial plates large, about twice as wide as 

 high, or more, the articulating scar very wide, occupying 

 more than half the entire width of the plate, leaving the 

 upper lateral faces conspicuous, and giving a heptagonal 

 form to the plate. Second radial plates short, broad, quad- 

 rangular. Tliird radial plates broad, pentagonal, with short 

 lateral sides. 



Arms very robust, sub-cylindrical, composed of very 

 strong plates, two from each ray at their origin on the 

 third radial plate ; those of the anterior ray without any 

 proper bifurcations, but throwing off branchlets alternately 

 on opposite sides. The arms of the antero-lateral rays 

 have the anterior division twice bifurcating ; above which 

 the divisions give off branchlets ; and the same feature 

 marks the entire length of the lateral arm of the antero- 

 lateral ray, which is smaller than the others. In the pos- 

 tero-lateral arms, the lateral division of the ray bifurcates 

 on the fourth plate, above which branchlets are thrown off 

 as in the others. The remaining divisions of the postero- 

 lateral rays are not known to bifurcate, (being broken 

 above the seventh plate,) but give origin to branchlets as 

 in the other divisions. Surface of plates granulose, undu- 

 lating, the angles depressed, giving a broad ridge or eleva- 

 tion to the sides of the plate ; these ridges radiate from 

 the centre of the sub-radial plates, giving a stellate form 

 to the elevated part of the plate. This feature is not al- 

 ways conspicuous. Column of moderate size, composed 

 of thin, alternately larger and smaller plates, with a large 

 perforation near the sunuuit. 



Geolog-ical formatiun and locality. Keokuk limestone, 

 Crawfordsvillo, Indiana. Collection of Wabash College, 

 from Prof. E. O. Hovcy. 



Cyathocrinus jjarvibrachialus (n. s,). Body dcprcssed- 

 sub-globose. Basal plates of medium size, pentagonal, 

 pointed at thek outer extremity, and forming by their 



