27 



POTEEIOCRINUS KASKASKIENSIS. N. SP. 



Body small, bell-shaped, nearly twice as wide as long to the sum- 

 mit of the radials, composed of rather thin, smooth plates, so closely 

 anchylosed together that their relative size and form cannot be 

 determined. The radials are nearly as long as wide, pentagonal, 

 thickened on their upper margins with a lip-like suture between 

 them and the first brachial plates. 



Brachials two, the first quadrangular, the second pentagonal ; 

 length and breadth about equal, botli rounded externally, and con- 

 stricted, the second sharply angular above, and supporting on its 

 sloping sides the first divisions of the rays. 



Arms composed of rather long, wedge-shaped joints, that project 

 slightly on their outer margins, giving them a somewhat zigzag ap- 

 pearance, and after their first division on the second brachials they 

 all divide again on the eighth to the tenth plate above the brachials, 

 giving four arms to each ray as the normal number. In one of our 

 specimens, however, one arm gives off a branch near its extremity, 

 making five arms to that ray. 



Pinnules rather strong and attached to the longest sides of the 

 arm plates. Anal plates unknown. Ventral tube cylindrical, and 

 about twice the diameter of the adjacent arms. 



Column round, composed of short, even joints, with numerous 

 cirrhi attached at short intervals on opposite sides, which are com- 

 posed of rounded joints about half the diameter of those composing 

 the column. 



This species may be readily distinguished from P. venustus and 

 P. clytis, by the bell-shaped form of its body and zigzag arrange- 

 ment of the arms. 



Position and locality : Chester limestone, bluffs of the Kaskaskia 

 river, four miles above Chester, 111. 



Illinois State collection. 



ZEACRINUS COXANUS. N. SP. 



Body of medium size, basin shaped, more than twice as wide as 

 high to the top of the radial series. Base depressed, and the basals 

 which are small, are concealed by the first columnar joints. Sub- 

 radials hexagonal, once and a half as wide as their hight above the 

 basal concavity, which is in part formed by the upward curvature of 

 their lower angles, their upper angles extending up nearly one half 

 the length of the radial series. 



Eadials nearly twice as wide as long, pentagonal, and truncated 

 squarely across their upper margins for the support of the brachial 

 series. The anterior ray has two brachials, the first one quadran- 

 gular, once and a half as wide as long, and the second short, pent- 

 angular, and supporting the first divisions of the ray. Each divi- 

 sion of this ray bifurcates again on the fourteenth or sixteenth plate, 

 the outer division, dividing again about the same distance above, 

 making six arms to this ray. 



