168 PALEONTOLOGY OF OHIO. 



single range of plates, with their longer faces alternately on opposite 

 sides. Thus in the upper part of the arm each alternate plate bears 

 a tentacle, and in the lower part of the arm each plate on each side 

 gives origin to tentacula. The tentacula are of moderate strength, rather 

 short, but composed of proportionally very long plates, which are cari- 

 nate on the back. The tentacula-bearing side of the arm plates is 

 characterized by a strong, projecting, spur-like process, upon which the 

 tentacula rest. 



The plates of the calyx are smooth to the naked eye, or under a lens of 

 moderate power. The arm plates have the margin bordering the suture 

 lines slightly elevated in the lower and middle portions of their length. 



Column small, round, composed of alternating larger and smaller 

 plates, the outer edges of which are rounded. 



This species strongly resembles P. graphicus in many features ; but the 

 arms are less strong, and arm plates different, the P. graphicus having 

 two distinct ranges of equal plates interlocking on the back and each 

 plate bearing tentacula, dividing on the second supraradial in one divi- 

 sion and on the third in the other divisions of the ray; while these 

 divide on the second supraradial in each division, so far as can be deter- 

 mined from the specimen. 



There may be some little doubt of the true generic relations of this 

 fossil, which can only be verified by the examination of more perfect 

 specimens. The whole aspect and mode of growth is that of Dichocrinus ; 

 but all the plates that are seen of the first radial range appear to be arm- 

 bearing plates ; the divisions of the basal series can not be distinctly 

 traced. 



Fwmation and locality : In the shales of the Waverly group, at Eichfield, Summit 

 county, Ohio. 



Platyckinus Lodensis (n. sp.). 



Plate 11, flg. 3. 



Body of moderate size, broadly pocilliform, the basal plates spreading 

 horizontally to near their outer extremities, above which the radial 

 plates appear but little expanded, with arm bases very strong in propor- 

 tion to the size of the body. Basal plates low and broad, forming a low, 

 pentangular, cup-shaped disc. First radials rather large ; height and 

 width, measured to the top of the lateral faces, about equal, the upper 

 surface protruding in the center, and deeply excavated for the support of 

 the somewhat broad, short, second radial plates, Avhich are very broadly 



