INVERTEBRATES. 301 



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. 



No. 2,452, Illinois State collection. 



POTEKIOCRINUS CULTIDACTYLUS, Hall. 



PL XXX, Fig. 1. 



Poteriocrinus cnltidadylus, HALL, 1859. 



Supplementary report on the Palaeontology of Iowa, p. 62. 



"Body elongato-turbinate and slightly expanding at the base of 

 the arms, which are regularly bifurcating and but slightly spread- 

 ing. Basal and subradial plates unknown. Eadial series consisting 

 of three plates in each ray, the upper one of which is a bifurcating 

 plate. First radial plates pentagonal, besides the truncated angles. 

 Second radials about as long as wide, quadrangular with truncated 

 angles. Third radials pentagonal, obtusely wedge-formed above, and 

 supporting on each side a series of eight arm-plates, the upper one 

 of which is a bifurcating plate; above this, on the outer side, there 

 is a bifurcation on the twelfth to the sixteenth plate, while the divis- 

 ion on the other side remains simple so far as can be traced in the 

 specimen. This character applies to all except the anterior ray, 

 where the bifurcation takes place on the twentieth plate above the 

 first division. 



The anal series consists of a number of small usually hexagonal 

 plates. 



The plates of the arms are round upon the exterior face, a little 

 wider on one side than the other in alternating order. The surface 

 is finely granulose, without peculiar markings." 



The above description was not drawn from the specimen figured, 

 but from one found many years ago, and now in the writer's collec- 

 tion, but was not accessible when the figures for this volume were 

 drawn. 



