5 J 



the left of the azygous area, if normal, will distinguish this 

 species from all others and as the ray on the right is the 

 same in each specimen we think the one on the left is normal. 

 The general form and surface ornamentation will distinguish 

 this from all other species having twenty arm openings to the 

 vault, though it resembles A. fossatus which has forty arm 

 openings to the vault. 



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

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



sampsonocrinus, n. gen. 



[Ety. The generic name is intended as a compliment to a dis- 

 Ungitishcd naturalist, Mr. F. A. Sampson, of Sedalia, Mo.] 



Body more or less globose. Basals three, subequal, one 

 pentagonal, two hexagonal. Primary radials either two or 

 three in each radial series and differing in this respect 

 in the different radial series in the same specimen. 

 Secondary and tertiary radials present. Interradial plates con- 

 nect with those of the vault, and, in three of the areas the 

 first plate abuts upon the basals, by which arrangement eight 

 plates unite with the basal disc. Vault elevated over the 

 ambulacral canals, and depressed in the interradial spaces. 

 Proboscis subcentral. Type S. hemisphericus. 



We refer this peculiar genus to the family Actinocrinidsc. 



SAMPSONOCRINUS HEMISPHERICUS, n. sp. 



Plate ITT, Fig. 7, basal view; Fig. 8, summit view; Fig. 9, 

 azygous side, the sutures between some of the plates 

 being obscure; Fig. 10, lateral view. 



General form of the calyx hemispherical, rather more than 

 one half wider than high, broadly rounded below. Plates 

 convex. Surface granular. Columnar facet very small. Arms 

 directed horizontally. 



One of the basal plates is pentagonal and two hexagonal, 

 and they differ but little in size. When united they form a 

 disc having three re-entering angles, in one of which an azygous 

 plate is supported, and each of the others support, a radial series. 

 The pentagonal plate is truncated by a radial and the hexagonal 

 plates arc truncated by a radial and by an interradial. By 



