INDIANA PALEONTOLOGY. J82. 



MEGISTOCRINUS SPINOSULUS, Lyon, Rowley. 



Plate 54. Figs. 5, 6. 



Our specimen is much depressed, the ventral disk being scarcely convex, 

 but little more than half of it preserved. The basals and first radials are in- 

 volved in a shallow concavity and without nodes, while the rest of the calyx 

 plates below the distichals have strong central spines. 



The vault appears to have had six nodes or spines but from the weathered 

 condition of this part of the fossil, the statement can not be positively made. 



Some specimens in our hands, however, have longer ventral than dorsal 

 spines and the smaller the specimen the more convex the vault. See plate 32, 

 figure 14 for M. rugosus. This species has very strong spines on the ventral 

 surface, while the dorsal plates above the first radials are only strongly convex 

 or warty. Even the smooth-plated species of Megistocrinus generally have 

 ventral spines, some times extravagant ones. See plate 24, figures 2, 3, 4. 

 Again, the tendency in the flat-plated species in large individuals is to have 

 concave calyx plates. See figures 3 and 4 on the accompanying plate. 



The specimen figured is from the Upper Helderberg limestone at the Falls of 

 the Ohio. Collection of G. K. Greene. 



STEREOCRINUS? INDIA NENSIS, M. &G., Rowley. 



Plate 54. Figs. 7, 8. 



The two specimens figured on our plate represent the form for which 

 Miller & Gurley proposed the above name. 



It is doubtful whether this species belongs to the genus Stereocrinus. It is 

 true it possesses but one costal but the specimen, figure 8, on our plate, has 

 a greater number of distichals to the calyx periphery. 



The basal plates are three in number and extend beyond the column base. 

 The first radials are hexagonal and the largest plates in the calyx. The second 

 radial or costal is pentagonal, of much smaller size and axillary. 



Resting on each bifurcating costal are double rows of distichals, eight or 

 more to the row in the imperfect dorsal cups figured, against two mentioned by 

 Wachsmuth & Springer in their diagnosis of the genus. 



The first interradial (interbrachial) is quite as large as the first radial, 

 eleven sided and longer than broad. 



Three much smaller plates rest on the upper edges of this first interradial 

 and above these are others but they can not be made out on our specimens. 



