19 



served in the specimen under examination, the first one pentagonal, 

 resting between two of the subradials, and partly under the sloping 

 side of the right posterior radial, the second and third are smaller, 

 one resting on the top of the left posterior subradial, and the other 

 on the first anal. 



Column rather stout, the upper joints filling nearly the whole 

 concavity of the base, and composed of thick and thinner joints 

 alternately arranged. 



Position and locality : Warsaw beds of the St. Louis group, near 

 Clayton, Adams County, 111. 



Illinois State collection. 



POTEKIOCRINUS ILLINOIENSIS. N. SP. 



Body of medium size, obconical, gradually tapering from the 

 summit of the radials to the base. 



Basal plates of moderate size, projecting more than half their 

 length beyond the column, and forming by themselves a low pen- 

 tagonal cup. 



Subradials as large or larger than the radials, two on the posterior 

 side heptagonal, the others hexagonal. 



Eadials rather wider than long, pentagonal, and truncated 

 squarely across their upper margins for the reception of the brachial 

 series. 



Brachials rather smaller than the radials, pentagonal, a little 

 constricted above, the upper angle obtuse, and giving support to the 

 first divisions of the rays. The arms are not preserved in the only 

 specimen yet found of this species, but from the very narrow plates 

 that are to be seen in one of the rays, they probably continue simple 

 above the first division on the brachial series. 



First anal plate longer than wide, pentagonal, and resting between 

 two of the subradials, and partly under the right posterior radial. 

 Second anal larger than the first, hexagonal, and resting on the 

 summit of the left posterior subradial, third anal smaller than the 

 first on which it rests, and above this a double series of small plates 

 are partly visible, that probably formed the base of the ventral tube. 



Column round, and near the base composed of joints nearly equal 

 ir thickness. 



Position and locality: Warsaw beds of the St. Louis group, 

 Warsaw, 111. 



Illinois State collection. 



POTEEIOCKIKUS VARSOUVIENSIS. N. SP. 



Body below the medium size, basin-shaped, a little more than 

 twice as wide as high to the top of the radial series. 



Base depressed, the basal plates and the lower angles of the sub- 

 radials forming the basal depression. 



Subradials on the anterior side hexagonal, sharply angular above, 

 and extending up about half the length of the radial plates. 



