55 



The secondary radials are directed nearly horizontally and 

 stand out, their full length, from the interradial areas. There 

 are' ten arm openings to the vault. 



There are three regular interradials in each area. The first 

 one is as large as a second primary radial and reaches about 

 as high, hexagonal, and supports two rather large plates that 

 unite with the plates of the vault. There are nine plates in 

 the azygous area. The first one is in line with the first pri- 

 mary radials and nearly as large. It is followed by two plates, 

 equally as large, in the second range. There are four plates 

 in the third range, though one of them touches one of the 

 plates of the second range only at an angle, and on each side 

 of the superior part there is a single plate. The last three 

 plates unite with the plates of the vault. 



The vault is highly elevated over the ambulacral canals and 

 correspondingly depressed interradially. It is covered with 

 numerous convex, polygonal plates and bears a large sub-cen- 

 tral proboscis. 



There is no described species very closely resembling this 

 one, though we have no doubt that we have before us a true 

 Amphoracrinas. 



The large specimen illustrated was found by R. A. Blair, in 

 the Chouteau limestone, at Sedalia, Missouri, and is now in 

 trie collection of S. A. Miller. The smaller specimen is from 

 the same rocks and is in the collection of F. A. Sampson. 

 The sculpturing is best preserved on the smaller specimen. 



Family MELOCRINIDjE. 



MELOCRINUS SAMPSONI, n. sp. 



Plate II , Fig. 27, basal view; Fig. 28, azygous side; Fig. 29, 



opposite view. 



Species above medium size. Calyx obconoidal, as far as the 

 secondary radials, which are directed horizontally, so as 

 to give the summit a pentagonal outline; truncated by large 

 column; diameter nearly twice as great as the height. Plates 

 highly convex and more or less radiately sculptured. 



The four basals form' a short rim, which is slightly lobed 

 by the depression of the suture lines, and almost covered be- 

 low by the end of the column. First radials the largest plates 



