22 



Second radials quadrangular aud very short, beino; from tliree 

 to six times as wide as long. Third radials pentagonal, twice 

 as wide as high, convex in the central part, axillary, and bear- 

 ing upon each upper sloping side two sscondary radials. The 

 second secondary radial is larger and much wider than the first, 

 axillary, and bears upon each upper sloping side two or three 

 tertiary radials. Ou one side of our specimen, there are on\y 

 two tertiary radials, in each series, aud on the other side there 

 are three, in each series, which makes one side of the calyx larger 

 than the other. The proximate ray on each side of tne azygous 

 area has an axillary tertiary radial so that each of these rays 

 has five arm openings to the vault. Tliis gives to the species 

 twenty-two arm openings to the vault. 



There is only one regular interradial in each area, which is 

 a large, tumid, oouspicuous plate. There are five azygous plates. 

 The first one is in line with the first radials and of nearly the 

 same size and (juite as tumid. There are three plates in the sec- 

 ond range, the middle one being a short quadrangular plate, 

 twice as wide as long, the lateral ones being comparatively large, 

 tumid plates. There is only one plate in the third range, which 

 is nearly as large as the first aud very tumid. The azygous area 

 is slightly wider than high, or nearly square in outline, with a 

 fiat, wide, quadrangular plate, in the center, surrounded b3' four 

 tumid jjlates occupying the angles of the square. 



Vault somewhat elevated over the arm openings, convex toward 

 the central part and having a subcentral proboscis. It is com- 

 posed of irregular, polygonal, tumid plates arranged, m some 

 order, as five quite tumid plates, half way from the margin to 

 the center, are in line with the primary radial series. The pro- 

 boscis beiug broken off, and the length is unknown. 



This species is so different from all others having twenty-two 

 arms, that it is unnecessary to make a comparison witli an}- of 

 them for the purpose of distinguishing it. The single, regular 

 interradial and the arrangement of the five azj'gous plates, with 

 their peculiar shape and convexity will alone distinguish it from 

 all other described species. 



Found by R. A. Blair, in the Burlington Group, at Sedalia, 

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



