38 



not willing, however, to propose a new generic name until some 

 author shall properly define Gilbertsocrinus or until we may have 

 an opportunity to examine a specimen belonging to the type 

 species in order to be assured that two genera are, in fact, in- 

 cluded under one name. We use the name Gilbertsocrinus, there- 

 fore, provisionally. 



This species, when compared with G. spinigerus, differs, in hav- 

 ing two plates in the second intersecondary range instead of one, 

 in having two plates in each of the three superior ranges in the 

 regular interradial areas instead of only one in part of them, in 

 the form of the third primary radials, in having a spine on the 

 first interradial plate, and in other peculiarities that distinguish 

 species. 



Found in the Hamilton Group near Charleston, Indiana, and 

 now in the collection of Wm. F. E. Gurley. The specific name is 

 in honor of its discoverer, Prof. G. K. Greene, the well known 

 collector at New Albany, Indiana. 



GILBERTSOCKINUS INDIANENSIS, n. Sp. 



Plate III, Fig. 16, basal view of a specimen preserving some com- 

 plete spines; Fig. 17, basal view of another specimen; Figs. 18 

 and 19, lateral views of same; Fig. 20, basal view of a 

 small specimen probably belonging to the same 

 species', Fig. 21, summit view of same; 

 Fig. 22, lateral view of the same 

 specimen with inter- 

 radial plates an- 

 chylosed. 



Calyx truncated at the base and summit, subpentagonal, in 

 transverse section, broadly constricted below the arms, height and 

 width subequal. Radial ridges angular. Very long spines on the 

 first and second radials and also on the first interradials. Basal 

 cavity broad and deep. Column round and pierced by a cinque- 

 foil canal. When compared with Gilbertsocrinus greenei, in the 

 above particulars, it will be found to have more angular radial 

 ridges, longer spines, deeper basal concavity, and spines on the 

 second radials that do not exist in that species. In the latter re- 

 spect it agrees with Gilbertsocrinus spinigerus, but not in the other 

 respects. 



