POTEKIOCEINUS TENDIDACTYLUS N. SP. 



Body obconical, length and breadth to the top of the radial plates 

 about equal. Basals well developed, expanding upward from the 

 column, forming a pentagonal cup rather wider than long. Subra- 

 dials about as wide as high, the one on the posterior side supporting 

 in part two quadrangular anal plates, that are succeeded by a double 

 series of smaller plates of the same form, forming the base of the 

 ventral tube. 



Eadials pentagonal, wider than high. Brachials four to each 

 of the posterior rays, three of them quadrangular and the fourth 

 pentangular, supporting on its upper sloping sides the first divisions 

 of the rays. The arms in the left posterior ray, after dividing on 

 the last brachial, give off a branch from each division, about the 

 twelfth to the twentieth plate, beyond which they are simple as far 

 as can be seen, giving four arms to this ray. 



The arms are long and slender, composed of rather long, rounded 

 joints, slightly zigzag in their arrangement, and give off rounded 

 pinnules from their projecting sides. 



The ventral tube, of which some traces can be seen an inch 

 above the base, appears to have been cylindrical, starting with the 

 two long quadrangular anal plates that rest on the posterior subra- 

 dial plate, the succeeding plates decreasing upward in size. 



Column at its upper extremity rather large, and composed of ex- 

 tremely short joints, closely anchylosed together. 



Position and locality : Upper part of the geode bed, one mile 

 l)elow Keokuk. 



No. 202 of Mr. L. A. Cox's collection. 



POTERIOCRINUS lOWENSIS. N. SP. 



Body short, about once and a half as wide as high. Basal plates 

 small and hidden by the first columnar joints. Subradials small, 

 slightly protuberant at the center and depressed at the angles. Ea- 

 dials twice as wide as long, pentagonal, depressed on their lower lat- 

 eral borders, with a tolerably well defined suture between them and 

 the brachials. 



Brachials two, the first quadrangular twice as wide as long, the 

 second pentagonal, giving support on their sloping angles to the first 

 divisions of the rays, and slightly protuberant at their upper angles. 



Arms after the first division on the second brachial in two of 

 the rays, the left posterior and right antero-lateral rays, divide again 

 on tlie fifth to the seventh plate, beyond which they are simple as far 

 as they have been preserved. On another ray which may l)e the an- 

 terior one, the first bifurcation takes place apparently on the fifth 

 brachial, and the second one on the third plate above, as near as can 

 be determined from the crushed C(mdition of this ray. Anal plates 

 unknown. 



Column round, composed of rather thick joints near the body, 

 becoming alternately thinner below. 



