107. CONTRIBUTION TO 



Smooth instead of nodose ventral plates, stronger central spine and shorter am- 

 bulacral spines, and less strong dorsal ornamentation. 



From Upper Devonian beds, near Charlestown, Ind. Collection of Mr, G. 

 K. Greene. 



GENN.E OCRINUS SCULPT US, N. Sp., (Rowley.) 



Peate 38. Figs. 4, 5, 6. 



In this fine species the length and width of the dorsal plates are about equal 

 and the first and second radials and the first interradials are about of the same 

 size. In the interradial to the right of the azygous area there are but two 

 plates in the second series, three in the third and four in the fourth. In the 

 other series there are three above the first and four in the third. The three 

 basal plates form a very low tripartite rim while the first radial nodes are 

 sharply elevated and produced outward. 



The mid-radial ridge is low and sharp to the middle of the third radial 

 where it becomes stronger, and rounded. 



The^plate ornamentation is low, sharp, radiating ridges. 



The ventral disk is low. almost flat, covered by small, slightly convex 

 plates. There are no ambulacral ridges inside of the arm lobes. The latter 

 are rounded, not constricted below and less prominent than on the preceding 

 species. 



The ventral spaces between the arm lobes are depressed and there are shorfe 

 spines over the groups of arm bases, with probably a low one at the dome-center.. 

 All the plates on the ambulacra are inclined to be tuberculous. 



The specimen is broken-in about the anal opening. 



Unlike the preceding species, this form has a very greatly inflated dorsal 

 cup and a slight constriction at the periphery and much stronger ornamentation. 



Like G. comptus and G. facetus, it has thirty arm bases, while G. Jien- 

 tuckleDsis has forty according to Wachsmuth and Springer. 



Locality, horizon and collection, same as the last. 



G E N N .E C R I N U S COMPTUS, Var. Spiniferus, N. Var. (Rowley. ) 



Plate 33. Figs. 7, 8, 9. 



This fossil agrees well with G. comptus in general outlines, character of 

 ornamentation, paddle-shaped arm-base lobes ; smooth, flat ventral plates and 

 central spine and in having thirty arms and excentric anus. 



