48 



Basals short, upright, and form an hexagonal disc. First pri- 

 mary radials the largest plates in the calyx, about as long as 

 wide, three hexagonal, two heptagonal, and each one bears a small, 

 central, transverse node. The constriction at the top of the basal 

 disc involves the lower part of the first radials. Second primary 

 radials quadrangular, two or three times as wide as long. Third 

 primary radials hexagonal or heptagonal, about one-half larger 

 than the second, axillary, and, in the ray opposite the azygous 

 area, supports on each upper sloping tide three secondary radials, 

 which gives to this ray two arms. In each of the other four 

 rays the third primary radial supports, on each upper sloping 

 side, two secondary radials, the last ones being axillary and sup- 

 porting on each upper sloping side two secondary radials, which 

 gives to each- of these rays four arms. There are, therefore, 

 eighteen arms in this species. The arm formula is 4+4+2+4+4. 



The interradial areas do not connect with the vault. In each 

 regular interradial area there are three plates, one followed by 

 two in the second range. In the azygous area there are seven 

 plates. The first one is in line with the first primary radials and 

 nearly as large as one of them. It is followed by three plates in 

 the second range and three in the third, which are cut off from 

 the vault by the union of the tertiary radials above them. 



The vault is elevated over the ambulacral openings, highly con- 

 vex, with slightly depressed interambulacral areas. It is covered 

 with polygonal, convex plates, and bears a subcentral proboscis. 



This is a handsome species, so different from all other eighteen- 

 armed species from the Burlington Group, that no comparison 

 with any of them is necessary. 



Found in the Burlington Group, at Burlington, Iowa, and now 

 in the collection of Mr. A. Albers. 



BATOCRINUS SUBROTUNDUS, n. Sp. 



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



side. 



The general form is depressed — rotund. The vault being as 

 large or larger than the calyx, and both slightly depressed longi- 

 tudinally at the margin at the top of the azygous area. Calyx 

 broadly saucer- shaped. No radial ridges. Arm openings directed 

 above an horizontal line and not visible in a basal view. Surface 

 plain and smooth. 



