55 



third range, there is a single plate. Above the last two plates 

 there are two elongated plates that unite with the plates of the 

 vault. 



The vault recedes from the ambulacral openings with slight 

 convexity, and then rapidly rises cone like, which is continued 

 slightly, subcentrally, in a large proboscis. The vault is covered 

 with polygonal, convex plates, the larger ones being nodose. The 

 ambulacral openings are above the calyx, on the flattened margin 

 of the vault, and are directed straight upward. 



This is a peculiar species, so different in its general appear- 

 ance and structure from all other twenty-armed species, that no 

 comparison with any of them is necessary to distinguish it. 



Found in the Burlington Group, at Sagetown, Illinois, and now 

 in the collection of Wm. F. E. Gurley. 



BATOCRINUS AFFINIS, n. 8p. 



Plate IV, Fig. 8, azygous view; Fig. 9, opposite view. 



Species small, somewhat biturbinate. Calyx obconoidal, trun- 

 cated, nearly as high as wide. No radial ridges. First primary 

 radials and interradials nodose. A small ovarian pore by the side 

 of each ambulacral opening. Ambulacral openings directed hori- 

 zontally. 



Basals form an hexagonal cup four times as wide as high, twice 

 as wide as the diameter of the column, slightly constricted in the 

 upper part, and having an hemispherical depression for the at- 

 tachment of the column, and a minute, round columnar canal. 

 First primary radials longer than wide, three hexagonal, two hep- 

 tagonal, and each one bears a central node. Second primary ra 

 dials quadrangular, twice as wide as long, and with the third 

 primary radials smaller thau the first. Third primary radials 

 about twice as large as the second, one hexagonal, four penta- 

 gonal, axillary, and in the ray on each side of the azygous area 

 the distal side supports two secondary radials and the proximal 

 side a single axillary secondary radial, which supports, on each 

 upper side, a single tertiary radial, which gives to each of these 

 rays three arms. In each of the other three rays the third pri- 

 mary radial supports, on each upper sloping side, two secondary 

 radials, which gives to each of these rays two arms. There are, 

 therefore, twelve arms in this species. The arm formula is 

 3+2+24-2+3. 



