26 



of the column. The basal plates stand upright, they are flat- 

 tened in the central part, and beveled toward the sutures, which 

 makes the cup hexagonal. It will be noticed that the basals 

 form a cup similar to that of B. aspratiUs, except having a 

 shallow, instead of a deep columnar cavity. First radials some- 

 what smaller than the basals, wider than long, three hexagonal, 

 two heptagonal. Each one is transversely tumid. Second radials 

 quadrangular and, at least, four times as wide as high, third 

 radials pentagonal, very short, four times as wide as high and 

 bearing upon each upper sloping side two secondary radials. 

 The second secondary radials are much wider than the first, 

 axillary, and bear upon each upper sloping side two tertiary 

 radials. There are twenty arm openings to the vault. 



There is only one regular interradial in each area, and it is a 

 large tumid plate. The azygous area is fully as wide as long 

 and contains four plates. The, first one is in line with the first 

 radials, rather larger and more tumid. There are three plates 

 in the second range, the middle one being about as large as the 

 other two together. 



Vault moderately elevated over the arm openings and quite 

 convex toward the central part. It bears a rather large, sub- 

 central proboscis, the length of which is unknown. The vault 

 is composed of irregulai' polygonal, subspinous plates, arranged, 

 so far as discovered, without order, in respect to the radial 

 areas. The proboscis commences at the base, opposite the azj^- 

 gous side, with a very large, transversely tumid angular plate. 



This species is so different from all other trochiform species 

 and from all others bearing twenty arms, that no comparison 

 is necessary to distinguish it. 



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

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



STROTOCRINUS VENUSTUS, U. Sp. 



Plate VI, Fig: 7, side and basal view of the caljx. 



Calyx medium size, urn shaped, below tiie tertiary radials, 

 from which place it abruptly spreads horizontally. Surface 

 deeply sculptured. Column round and perforated by a rather 

 large subpentagonal canal. 



Basals low, thick, deeply sculptured, notched at the suture 

 lines, hexagonal in outline and extending below the columnar 



