21 



fers from their '' Cyatliocrimis fiorcalis" in the form and relative pro- 

 portion of the body plates, as well as in the bifurcations of the arms. 



Position and locality : Chester limestone, Monroe county, 111. 



Illinois State collection. 



POTERIOCRINUS SALTERI. N. SP. 



Body small, basin-shaped, rather more than twice as wide as 

 high. Base depressed, and basal plates concealed in its concavity. 



Subradials about as long as wide, those on the anterior side hex- 

 agonal, the lower angles curving into the basal depression, protu- 

 berant, and slightly depressed at their upper angles. 



Eadials pentangular, about once and a half as wide as long, 

 slightly depressed at their sides and lower angles, and showing a 

 distinct suture above, vvdiere they join the brachial plates. 



Brachials two to the anterior ray, the first one of which is quad- 

 rangular, and wider than high. The second is pentagonal, longer 

 than wide, its upper angle produced into an obtuse node, and sup- 

 porting on its upper sloping sides the first divisions of the arms. 

 The two antero-lateral rays have a single brachial, about the same 

 size and form of the second brachial on the anterior ray, and sup- 

 port on their upper sides the first divisions of the rays. 



The arms are composed of rounded, quadrangular joints, and all 

 divide again on the sixth plate above the brachials, which is nodose 

 like the brachials, and beyond this they appear to be single to their 

 extremities, giving four arms to each ray. Pinnules rather strong, 

 and are given off on alternate sides from the upper margins of the 

 arm plates. Anal plates unknown. 



Column round, composed near the body of thick and thinner 

 joints alternately arranged. 



Position and locality: Chester limestone, Chester, 111. 



Illinois State collection. 



I take pleasure in dedicating this pretty species to Mrs. J. C. Sal- 

 ter, of Chester, in recognition of her enthusiastic labors in collect- 

 ing the fosils of that very interesting locality. 



POTEEIOCRINUS SCULPTUS. N. SP. 



Body of medium size, basin shaped, about twice as wide as high 

 to the top of the radial series. 



Base depressed, and the basals nearly concealed by the upper 

 joints of a large pentalobate column, composed of thin plates with 

 crenulated margins. The outer angles of the basals are barely visi- 

 ble in the pentalobate depressions of the column. The column 

 decreases rather rapidly m size below its junction with the body. 



Subradials a little wider than high, the two posterior plates a little 

 larger than tiie others, and all crossed by two or three rounded 

 ridges that culminate in the center of the plate in a sharp node. 



