78 



for the reception of the interradials. The facets for the articu- 

 lation of the seuond radials are not preserved, but the ambu- 

 lacral canals make a delicate notch in the middle of each 

 first radial. 



The vault is elevated and convex, the first interradials are 

 large and stand nearly upright, but curve the superior end 

 slightly over on the vault. The ambulacral canals are remark- 

 ably deep and form elevated rounded ridges on the summit of 

 the vault; in other words, they cut the first radials and form 

 the highest part of the vault. The vault is covered with 

 polygonal plates, the central one being about as large as an 

 iuterradial. The proboscis is sub-central. 



While there are some pentagonal, bowl-shaped species that 

 the calyx of this species resembles, there are none described 

 having any such vault as this one has. 



'■ iPound in the chert belonging to the Burlington Group at 

 S?dalia, Missouri, and now in the collection of S. A. Miller. 



PLATYCRINUS GERMANUS, n. Sp. 



Flide IV, Fig. 4(1, side view, the spines may he foreign matter; 



Fig- 47, basal view, one plate is pushed a little out of 



place, and the spiiies on one belong to foreign material. 



Species medium size. Calyx somewhat obpyramidal, r-ather 

 rapidly (expanding esi)ecially toward the arm bases, which 

 givQS to the upjier part a pentagonal outline; truncated below, 

 only to the extent of the diameter of the column: diameter 

 al)out one-half more than tlu; height; surface granular: 



Basals form a cu]) two and a half times the diameter of the 

 column, the lower part having a concave depression for the 

 uVtaohment of this column without any .svirrounding rim. The 

 facets supi)orting the radials are slightly concave. First radials 

 q, ^little longer than wide, gi"idually exjianding, convex longi- 

 tudinally, depressed towards the sutures, and most tumid 

 toward the second radials. Articulating facets directed upward 

 at an angle of about forty five degrees, form more than half a 

 circle, and occupy about half the diameter of each plate. Only 

 slightly notched in the central part. Second radials short and 



jaxillary. 



* " ' i •" 



