ICHTHYOCRINIDAE 299 



sutures, and strongly buttressed side margins. IIBr 3; IIIBr 4 on inner rami 

 of dichotom, and 5 to 7 on outer. Arms infolding beyond the 4th bifurcation. 

 Column small, cylindrical, with nearly uniform ossicles, slightly alternating in 

 length. 



This species is distinguished from all others by its broadly rounded crown, small basal 

 and infrabasal plates, and highly arched and buttressed brachial plates. It wholly lacks the 

 pyriform or elongate contour and evenly curved plates of the type, or of its American con- 

 geners. The infrabasals have retreated to the column facet as in Ichthyocrinus. The figures 

 indicate a faint surface ornament, which proves to be not organic, but the result of chemical 

 action, affecting most of the crinoids of the same locality. The species is not uncommon in 

 the Helderbergian beds, at Keyser, West Virginia. 



Types. In the collection made by Professor Frank Hartley, of Cumberland, Maryland, 

 now belonging to the author. 



Horizon and locality. Helderbergian, Keyser formation ; Keyser, West Virginia. 



Clidochirus schucherti (Talbot) 

 Plate XXXVII, figs. 12-13 



Ichthyocrinus schucherti Talbot, Amer. Jour. Sci., XX, 1905, p. 30, pi. 3, fig. 1 and text-fig. 4. 



A medium sized species. Crown short, conical, with rather narrow base, 

 expanding uniformly to about the middle IIIBr, and becoming strongly con- 

 tracted above that by the infolding of the arms. Spread of calyx from base to 

 upper IIBr, about I to 3; height to width at that level, 1 to 1.5; side outline but 

 slightly convex; cross-section circular; base larger than proximal columnal. 

 Surface smooth. Crown of maximum specimen, 27 mm. high by 20 mm. wide 

 at upper IIBr; width of base at IBB, 6 mm. 



IBB small, not visible beyond the column. Basals large, showing a full 

 pentagon in side view. Anal x large, perhaps followed by another. RA smaller 

 than R in other rays. Br 4 times wider than high, evenly curved, without sur- 

 face angularity or imbrication; IIBr mostly 4, abnormally 8; IIIBr 5 to 8 or 

 more, with another bifurcation visible in some rays. Column of good size, 

 proximal columnals not enlarged; alternating nodal joints becoming rounded 

 a short distance below. 



This species was founded upon a specimen from the New Scotland beds of the Helder- 

 bergian of New York, and described under Ichthyocrinus. Miss Talbot's description and 

 diagram, 1 while in other respects excellent, are not correct in representing four primary 

 plates in each ray. The specimen is partly imbedded in the matrix, leaving only three rays 

 exposed, and these injured by weathering, so that the plates can be well distinguished in only 

 two of them. One has four, the other three. No other species or specimen of this family is 

 known in which there are four primary plates (radial and three primibrachs) in all the rays, 

 except in the Carboniferous. From these facts we must infer that the ray with the four 

 plates is the right posterior with the radianal in primitive position, and that there are a radial 

 and two primibrachs in each of the other four rays. 



This is confirmed by the discovery of another specimen from the same horizon in New 

 York in which the crown is free and the anal structures clearly shown, thus leaving no doubt 

 as to its generic position under Clidochirus. The stem in the type specimen also is that of this 



1 American Journal of Science, vol. 20, 1905, p. 30, text-fig. 4. 

 20 



