CRmOIDEA OF THE WAVEELY GROUP. 163 



This species resembles the A. eucharis and A. Calypso, of the Hamilton 

 group, differing from the first in the number of arms, and in having the 

 subdivisions of the ray beginning as it becomes free from the cup ; and 

 from the latter it differs in the greater number of arms from the ray, as 

 well as in the angular character of the supraradial plates. 



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

 Summit county, Ohio. 



ACTINOCEINUS HELICE. 



Plate 11, figs. 5-8. 



Actinocrinus helice; 17th Eept. on the N. Y. State Cab. of Nat. Hist., p. 53, 1864. Extr. 

 published 1863. 



Body short, broadly turbinate, the base overhanging the column. 

 Basal plates somewhat deeply notched at the suture lines; first radial 

 plates proportionally large ; second radials small, quadrangular ; third 

 radials slightly larger than the second, pentangular, supporting supra- 

 radial and brachial plates on the upper sloping sides. 



In the anterior ray the third radial supports simple brachial plates 

 only, giving origin to two arms ; in the antero-lateral rays the third 

 radial supports a supraradial or bifurcating plate on one side, and simple 

 brachial plates on the other, giving three arms. Sometimes there are 

 two bifurcating plates in these rays, giving origin to four arms in one or 

 both these rays. 



In the postero-lateral rays the third radial plate supports a bifurcating 

 supraradial on each side, giving origin to four arms to each ray, making 

 a formula of 



33=16 arms, or 11^17 arms. 



4 4 4 4 



A constant feature of this species, so far as observed, is the existence 

 of two arms in the anterior ray, and four in each of the postero-lateral 

 rays, while in the antero-lateral divisions there may be two, three, or 

 four arms in one or both rays. 



Interradial areas with the first plate large, and one or two plates above 

 it. First anal plate large, heptagonal, round and nodiform in the mid- 

 dle, supporting three plates in the second range, with two or three small 

 ones above. 



Arms stout and of moderate length, composed of a double series of 

 plates, the center of which are elevated, producing transverse angular 

 ridges. In the upper part of the arms these ridges are broken into nodes, 

 which are sometimes sharply elevated. 



