CLINTON GROUB. 



m 



Fig. 12 «. A longitudinal section of the last, showing the tube filled with fragments of crinoids 

 and shells*. 



Position and locality. In the upper limestone of the group at Lockport, Niagara county. 



Genus DISCOSORUS {nov. gen.). 

 [Gr. (Sio'xo?, discus, and rfupos, cumulus. \ 

 A body composed of discs or rings piled one above another, and gradually diminishing in 

 nze ; outer edges rounded, joining surfaces broad and flat ; internally fibrous or solid. 



I propose this name for a peculiar fossil body whose relations are at present unknown to 

 me ; and having but a single species, it is scarcely possible to give the generic characters that 

 degree of comprehensiveness that may be required. 



495. 1. DISCOSORUS CONOIDEUS (n..f^.). 



PL. XXVIII. Fig. 13 a, b, c. 



Body conical, composed of a series of rings which are flattened above and below, each 

 succeeding ring or disc increas'mg in size from the apex to the base ; exposed edges of the discs 

 rounded ; joining faces flat and smooth, without apparent marks of articulation of any kind ; 

 open or hollow in the centre ; substance of the discs fibrous, radiating towards the outer margin. 



This peculiar fossil body differs from the Corxulites in the mode of articulation or joining 

 of the discs, and also in the structure of the substance composing it. It does not, indeed, 

 appear in the least degree allied to the preceding genus. Two specimens have been examined, 

 both presenting the same essential characters ; and though they do not appear to be entire, 

 yet their structure furnishes no clue to their affinities. In the cavity of one of these specimens 

 there is a mass of crushed crystalline plates of some crinoidean, which has led me to infer that 

 they may belong to a cystidean. The substance of the discs, however, does not present the 

 usual characters of crinoidean or cystidean columns ; though one can not fail to perceive some 

 analogy between these and the peculiar crinoldal joints from the ore beds of this group, and 

 which are described with the Crinoidea in the same connexion with those of the Niagara group. 



Fig. 13 a. One of these bodies of the natural size, preserving eight or nine rings from the apex 



to the base. 

 Fig. 13 6. The base of one of these discs from another individual. 

 Fig. 13 c. A section of one of these discs exposed by fracture, showing the radiating and fibrous 



structure of the body. 



Position and localities. A single specimen has been found in the green shale near the Ridge 

 road in the town of Ontario, Wayne county ; and another specimen in the lower part of the 

 group at Lockport, Niagara county. 



* It seems scarcely possible that tliese bodu-s can be the columns of Cystideans, as suggested by Prof. Forbes; 

 since they are hollow tubes filled with extraneous drifted materials, and do not present the usual structure as to 

 arrangement and character of plates or rings, which are seen in the fragments of cystidean columns examined. 

 Ther« i» at least little analogy with those from the Niaj^ra and Helderberg roeki, though it is possible that th^ 

 may belong to some similar bodies 



