INDIANA PALEONTOLOGY. 102. 



Aorocrinus. The only ditferences of much note are the inflated character ot 

 the dorsal cup in Gennteocrinu!?, the flat ventral disk, greater number of arms, 

 less extended basal rim and surface ornamentation. 



I) O L A T O C K 1 X U S , Sp? 



Platk 32— Figs. 10, 11, V2. 



This little Dolatocrinus has but four arm groups, the place of the fifth 

 looking like an anal interradius. The base is flat and a slight rim surrounds the 

 column. The radial plates possess strong nodes, connected b}' a strong ridge. 



The large interradials have each a strong central node from which radiate 

 eight or more ridges. 



The body is constricted below the arm bases. 



There are nine arms, arranged as follows, 3, 2, 2, 2. 



The ventral disk is convex and the ornamentation is numerous short radi- 

 ating lines and granule-like tubercles. 



The anal opening is medium in size. 



From the Upper Devonian beds, near Charlestown, Ind., and in the collec- 

 tion of Mr. G. K. Greene. 



M E G I 8 T O C R I N U S R U G O S U S . var. Spinuliferus, N. var. (Rowley) 



Plate 32. Figs. 13, 14, 15. 



A specimen of this variety is figured in Wachsmnth and Springer's great 

 work on the Crinoidea Camerata as the young of J/, rugosus. Our type has 

 all the appearance of an adult form. It has an almost central proboscis, elon- 

 gate tubercles or spines on the vault, greatlv" nodose calyx plates above the 

 first radials, fiat basal and first radial plates, these latter forming a flat area, 

 hardly concave, even at the stem base. 



The vault spines are along the ambulacral ridges and on the proboscis 

 {ventral tube). 



There are sixteen arm openings and apparently two respiratory pores to 

 the arm. 



The specimen figured is from the Upper Devonian beds, near Charlestown, 

 Ind., and now in the collection of Mr. G. K. Greene. 



DOLATOCRINUS ASPRATILIS. M. & G., Rc.wley. 



Plate 32. Figs. 16, 17, 18. 



A rather deep funnel occupies the base of this fossil, to the centers of the 

 first radials, bounded above by a pentagonal rim formed by strong ridges, con- 

 necting the central tubercles of the first radial plates. 



