CRIXOIDEA OF THE WAVERLY GROUP. 175 



havinp^ a shorter and comparatively broader body and much shorter 

 basal plates. In this species every arm joint bears tentacula, while in 

 the Hamilton species the tentacula arc only on every second or third 

 joint. 



Above the horizon of the Poteriorrinus diffusus there are as much as one 

 thousand feet of Genessee slate and Portage rocks, and one thousand 

 feet of beds belonging to the Chemung group of New York, before reach- 

 ing the horizon to which these fossiliferous beds in Ohio have been re- 

 ferred. 



Formation and Jocaliiy : In shales of the Waverly group, at Richfield, Summit, 

 county, Ohio. 



SCAPHIOCRINUS (POTERIOCRINUS) LYRIOPE. 



Plate 12, fig. 10. 



Scaphiocrinus {Poteriocrinus) Jyriopc ; 17th Rept. on the N. Y. State Cab. of Nat. His., p. 

 58, 1864. Extr. published 1863. 



Body small, sub-turbinate. Basal plates of moderate height, and 

 much wider than long. Sub-radial plates about equal in height and 

 breadth ; first radial plates about once and a half as wide as high ; sec- 

 ond radials much higher than wide, some of these twice as high as 

 wide, strongh" constricted on the sides, obtusely wedge-form above, and 

 supporting an arm on each upper sloping face. 



Arms long and slender, composed of a single series of elongate, curv- 

 ing plates, which are alternately longer and shorter on the opposite 

 sides, and constricted in the middle. A single arm is seen to bifurcate 

 on the tenth plate above its origin. The upper lateral angle of each 

 arm plate is much thickened and expanded for the attachment of strong 

 tentacular plates. The tentacula are composed of strong, elongate plates, 

 which are distinctly grooved on the inner face ; the exterior surface lon- 

 gitudinally striated. 



Surface of plates of the body and arms distinctly striato-granulose. 



Column near the body small, round, or very obtusely pentagonal, and 

 composed of irregularly alternating longer and shorter plates. 



In general features this species resembles Poteriocrinus xgina, but is 

 somewhat more delicate, and the calyx scarcely so spreading. The sec- 

 ond radial is a bifurcating plate (instead of the third), and is much 

 longer than the third plate in P. /vgina; the arms and tentacula are 

 more slender; the arm plates not so prominent at the the junction of 



