10 



All of the interradial areas connect with the vault. There 

 are four plates in each regular interradial area, one in the first 

 range, two in the second, and one in the third, which sep- 

 arates the radial series and unites with the plates of the vault. 

 There are fourteen plates in the azygous area. The first our 

 is in line with the first primary radials and of about the saiiic 

 size: it is followed by three plates in the second range, six 

 plates in the third range, and four in the fourth range, two of 

 which unite with the plates of the vault. One of the four 

 plates, in the last range, is to the left and another is inter- 

 calated between the lower part of the two larger plates that 

 unite with the plates of the vault. 



The vault is depressed, convex and covered with small, con- 

 vex, polygonal plates and lias a subcential azygous orifice 

 slightly elevated above the greatest convexity of the vault, 

 but it could hardly be regarded as a proboscis. No ovarian 

 pores can be discovered. 



This is a very peculiar species and so different from all 

 other eighteen-armed species that no comparison with any of 

 them is necessary. 



Found by F. A. Sampson, in the Keokuk Group, at Boon- 

 ville, Missouri, and now in his collection. 



BATOCRINUS SIGNATUS, n. sp. 



Plate I, Fig. 16, azygous side; Fig. 17, opposiie view. 



Species medium or below medium size, biturbinate. Calyx 

 broadly truncated, obpyramidal, about twice as wide as high. 

 Radial ridges angular and well denned. Interradial areas flat 

 tened. Ambulacral openings directed a little above a horizon- 

 tal line. 



Basals form an hexagonal disc that is expanded in rim around 

 the base of the calyx. Diameter a little greater than the 

 diameter of the column, and height about equal to the thick- 

 ness of the plates. Shallow concave depression for the at- 

 tachment of the column. First primary radials a little wider 

 than long, longitudinally angular in the middle part, three 

 hexagonal, two heptagonal. Second primary radials short, 

 quadrangular, three or four times as wide as lone-. Third 



