82 



radials. The facet has an inclination of nearly forty- five degrees. 



The first radials are truncated, at the superior lateral angles, by 

 single interradial plates. A small, triangular, elongated, azygous 

 plate is intercalated between the subradials and below the first 

 radial, on the right of the azygous area. Another quadrangular 

 azygous plate, longer than wide, broadly truncates a subradial and 

 separates two first radials. These two azygous plates do not come 

 together. 



This species is distinguished by the rapid increase in size from 

 the basals to the first radials. By the great thickness and con- 

 vexity of the plates, without angular pits. Inclined facet for the 

 second radials, and by the azygous plates. 



Found by F. A. Sampson, in whose honor we have proposed 

 the specific name, in the Burlington Group, at Sedalia, Missouri, 

 and now in his collection. 



POTERIOCRINUS BOZEMANENSIS, n. sp. 



Plate V, Fig. 11, side view, natural size, showing part of the 

 proboscis; Fig. 10, same magnified two diameters. 

 The specimen is on a slab. 



Species very small. Calyx obconoidal, one-third wider than 

 high. Plates rounded, with the slightest convexity, but showing 

 the sutures. Surface apparently smooth. Column small. 



Basals small and extended but little beyond the column. Sub- 

 radials two or three times as large as the basals and nearly as 

 long as wide. First radials very little if any larger than the sub- 

 radials, a little wider than long, and truncated the entire width 

 above for the first arm plates, from which they are separated by 

 a very slightly gaping suture. The arms do not bifurcate, and 

 hence there are only five arms in this species. The first plate is 

 very long and round externally, but the plates rapidly shorten 

 and bear alternate pinnules. 



The azygous area is not exposed in our specimen, but from the 

 form of the calyx and the piece of the proboscis that is exposed 

 there can be little or no doubt of the generic relations. The part 

 of the proboscis which is exposed and illustrated is round and 

 composed of four series of plates. 



This is a peculiar species, and so different from all others that 

 no comparison with any of them is necessary. 



