INDIANA PALEONTOLOGY. 72, 



MEGISTOCRINUS EXPANSUS, Var. INFLATUS, 



N. var. (Rowley). 



Plate 24. Figs. 5, 6-7. 



The calix of this handsome Megistocrinus is low bowl shape. The basal 

 plates and first radials are involved in the dorsal concavity which, however, is 

 shallow, but broad. 



The second radials and first interradials, form a more or less flattened zone 

 surrounding the concavity. 



The plates of the calix are of the normal number and arrangement, slightly 

 concave and ornamented by fine radiate lines and granules. The ventral disk 

 is somewhct inflated and made up of numerous small plates, flat or insensibly 

 convex, apparently smooth. There are sixteen arm bases, grouped as follows: 

 Beginning with the ray to the right of the anal region and going to the right, 

 4, 2, 4, 2, 4. The central dome plate bears a low spine and the plate at the 

 junction of the ambulacral furrows, either side of the anal opening are simi- 

 larly spinous, but the spines (three in number) are of much less size than those 

 on M. Corniger. • 



The groups of arm bases are separated by depressions, as also the ray di- 

 visions to a less extent. 



The anal opening is eccentric and apparently large. 



One of the second interradials has a smooth, round hole through it. as if 

 bored by some marine worm or other aquatic organism, and portions of both 

 the calix and dome have barnaele-like shells attached, but all of these have 

 been omitted in the drawing. 



This fossil is near to Miller and Gurley's M. Expansus. but seems to ditfer 

 sufficiently for the separation as a variety. 



It was found in the upper Devonian beds near Charlestown. Ind., and be- 

 longs to the private collection of Mr. G. K. Greene. 



MEGISTOCRINUS CIRC UL US, N. Sp. (Rowley). 



Plate 24. Figs. 8, 9-10. 



This unique crinoid has a low calix, expanding toward the circle of arm 

 bases from the region of the second radials. The basals, first radials and parts 

 of the second radials form a decided concavity, much more so than in the 

 species above noticed. The usual arrangements and number of calix plates, 

 modified to some extent to conform to the shape of the cup, flat or slightly 

 eoacave, with low, fine linear orn\mentation, app.irently without definite ar- 

 rangement. 



