FOSSIL CRINOIDS. 121 



above and between them in the tegmenal axil. Arms unknown. Interbrachial 

 spaces wide, occupied by about 5 ranges of plates, in order 1, 2, 3, etc., in the 

 dorsal cup, and several more above the level of arm bases, between the lobes 

 to a connection with the orals. Anal area similar, with 3 plates in the second 

 range, leading to a subcentral opening in the tegmen, directed up. Tegmen 

 high, low convex on top, broadly curving down interradially between the lobes, 

 which are very high, surmounted by the protuberances already mentioned; 

 •these are hollow, composed of small plates, and formed the sockets for large 

 spines, none of which are preserved; tegmen plates very small and numerous; 

 orals not differentiated. Column facet round, filling entire width of base. 



Types. Figs. V2a-d are in Walker Museum, University of Chicago. Fig. 13, 

 in author's collection. 



Horizon and Locality. Hamilton Group, Middle Devonian. Charleston, 

 Clark county, Indiana. 



Besides the two very good specimens figured, I have three others not so 

 complete, but showing the characters of the species with remarkable constancy; 

 the low radial ridge is equally distinct in all. The nearest related form to this 

 that I know is the species from an about e([uivalent horizon in the Eifel, de- 

 scribed by Schultze as Rhodocrinus quinquelobus (Mon. Echin. Eifelk., 57, 

 PI. VH), which has a similar narrow, turbinate, elongate calyx, with prominent 

 lobes in the radial regions; but no spines. This species has been the subject 

 of uncertain treatment in systematic literature. Schultze declared its affinities 

 to he with Thysanocrinus, as a subgroup within Rhodocrinus. Wachsmuth 

 and Springer accordingly placed it under Eucrinus on account of its 20 arms. 

 Afterwards, following Schultze's diagram (loc. cit., 57, text-fig. 10), we withdrew 

 it from that group, considering it a Rhodocrinoid (N. A. Crin. Cam., 192); 

 neither of these assignments can stand. The difficulty grows out of the above 

 mentioned diagram, which is wholly incorrect and misleading; how Schultze, 

 careful observer as he usually was, could have constructed it from his specimen, 

 is more than I can understand. The diagram represents a dicyclic Crinoid 

 with radials separated all around by a large interradial plate; it was based upon 

 a single "ziemlich unvollstandigen " and "verdriickte" specimen, in which 

 the posterior side was chiefly exposed, and of which only that view is figured 

 (loc. cit., PI. VII, 6). This figure shows three large basal plates, each followed 

 alternately by large, somewhat nodose, radials, and these in succession by two 

 primibrachs, the second one axillary and leading to two arm openings; that is, 

 four ranges of plates up to and including the axillary brachials (radials of third 



