CEINOIDEA OF THE WAVERLY GROUP. 169 



or obtusely cuneate above, and support each two supraradials on each 

 side, one above the other ; the upper of these is a bifurcating plate, and 

 supports the first arm plates, one on each slope, giving four arms to each 

 ray, arranged in even pairs. 



Arms of moderate length, proportionally strong, of nearly equal size 

 throughout the entire length, full and rounded on the sides and back, 

 composed of a double series of short, broad plates, interlocking at their 

 inner edges along the middle of the outer side of the arm. Tentacula 

 not discovered, but doubtless existed on each plate. 



Surface of the plates of the body apparently smooth or very finely 

 granulose ; surface of arm plates finely granulose, the suture lines very 

 faintly channeled. 



This species difiers from P. grapldcus in the form of the calyx, which 

 is much broader below, and also in the strong, protruding arm bases. It 

 belongs to the group of the genus represented by P. Wortheni and P. Shu- 

 mardiana, but is specifically distinct from any we have seen, and differs 

 from the two named in the absence of ornament on the calyx, in its 

 greater height, and in the arm arrangement. 



Formation and locality : In the calcareous layers of the Cuyahoga shale, Waverly 

 group, at Lodi, Medina county, Ohio. Collection of Columbia College, New York. 



Genus FORBESIOCRINUS, DeKoninck. 

 FORBESIOCRINUS COMMUNIS. 



Plate 12, figs. 3-5. 



Forhf'siocrinus communis; 17th Rept. on N. Y. State Cab. of Nat. Hist., p. 55, 1864. 

 Extr. published 1863. 



Body in the young state regularly turbinate, and becoming more 

 spreading in older specimens. Basal plates sometimes appearing as a 

 thicker projecting rim, more or less complete, at the summit of the col- 

 umn ; sub-radial plates small, sub-triangular, the lateral edges scarcely 

 truncate. Primary radials, four, wider than high; secondary radials, 

 from four to seven, varying in the different rays, smaller than the pri- 

 mary radials, and in different proportionate strength in different indi- 

 viduals. Each ray is usually three times divided, and rarely some one 

 of the divisions again bifurcates, while in some individuals the third 

 bifurcation is not complete. 



The interradial spaces in the older individuals are marked by the pres- 

 ence of a single plate, while in the young specimens no distinct plate, 



