166 PALAEONTOLOGY OF OHIO. 



Column of medium proportions, composed of alternating thicker and 

 thinner joints. 



In the mode of arm-bifurcation this species resembles the A. Whitei, of 

 the Burlington limestone; the form of the body is very different. In 

 this, the arms become free above the third radial plates, while in that 

 they are united to the cup by interbrachial plates, and rise from the 

 body in ten divisions ; and these are free before subdividing, and present 

 but five arms where they become free from the body. 



Formation and locality: In shales of the Waverly sandstone group, at Kichfleld, 

 Summit county, Ohio. 



Gbnus PLATYCRINUS, Millof. 

 Platycrinus contritus. 



Plate 11, fig. 4. 

 Platycrinua contritus; 17th Rept. on the N. Y. State Cab. of Nat. Hist., p. 54. Extr. 

 published 1863. 



Body broad and short, broadly truncate and concave at the base for the 

 reception of a large column. Basal plates forming not more than one- 

 third the height of the cup, projecting at the base ; first radial plates 

 wider than high ; second radials sub pentangular, with short lateral 

 sides. , 



Arms short and strong, composed of a double series of plates, bifur- 

 cating on the second radial. Divisions, four from each ray, except on the 

 postero-lateral ones, where there are three on the anal side, maliing 

 five to each of these rays, giving a formula of 



l4=22 arms. 



Surface smooth. Column unknown. 



This species is of the type P. Burlingtonensis, and its varieties. 



Formation and locality: In shales of the Waverly sandstone group, at Richfield, 

 Summit county, Ohio. 



Platycrinus graphicus. 



Plate 11, fig. 2. 



Platycrinus graphicus; 17th Rept. on N. Y. State Cab. of Nat. Hist., p. 55. Extr. pub- 

 lished 1863. 



Body sub-hemispherical, rounded below, the basal plates making less 

 than' one-third the height of the calyx. First radial plates wider than 

 high; second radials broad and short, sub- pentagonal. 



