130 PALAEONTOLOGY OF OHIO. 



above the base of the ambulacral areas the summit forms a short five- 

 sided pyramid, with slightly concave spaces between the ambulacral 

 areas. Radial plates long and narrow, three and a half times as high as 

 wide; length of basal plates unknown ; height of the summit pyramid a 

 little more than half as great as the greatest diameter of the body; while 

 the diameter of the body is about equal to three-fifths of the length of 

 the radial plates, measuring at the base of the ambulacral areas. Am- 

 bulacral areas narrow, gradually increasing in width from the lower part 

 .upwards ; number of plates filling the areas not determined. 



The description is taken from an internal cast, imperfect at the lower 

 extremity, and, consequently, a full description can not be given. The 

 form of the crinoid corresponds very nearly with that of P. Reinwardti, 

 Troost, and it is principally the interest connected with the occurrence 

 of another species so nearly allied to that one, in a similar geological 

 position, that has offered the temptation to describe it from such meager 

 material. The general form of the body has been much straighter above 

 the basal plates, when compared with that one in the condition of casts, 

 and the top of the summit jiyramid considerably broader. 



Formation and locality: In limestones of the Niagara group, at Yello\Y Springs, Ohio. 

 Collection of Prof. E. Orton. 



BRACHIOPODA. 



Genus DINOBOLUS, Hail. 



(Notes on some new or imperfectly known forms among the Brachiopoda, etc., p. 4, 

 1871 ; also 23d Kept. State Cab., p. 247. ) 



DiNOBOLUS CONRADI. 



Plate 7, figs. 3, 4. 



'Obolus Conradi, Hall ; 20th Eept. State Cab., p. 368, pi. 13, figs. 1, 2, 3, 1868, and 2d Ed., 



1870, p. 375. 

 Dinobolus Conradi, Hall; 23d Rept. State Cab., p. 247. 



A single individual of this species has been detected among specimens 

 from the Niagara group, at Crawford, Wyandot county, Ohio, preserving 

 the usual features of the species, so far as can be determined from the 

 imperfect condition of the specimen. The individual consists of an in- 

 ternal cast of both valves of a full-grown shell, but displaced and quite 

 imperfect. The form is transversely broad oval, very symmetrical in 

 outline, and gently convex on both sides ; giving a lenticular profile to 



