16 



supporting on its upper sloping sides the first divisions of the ray. 

 In the left posterior ray the hrachial is divided, making two 

 brachials in this ray, the first quadrangular, and the second short 

 and pentangular, but I am inclined to regard this as accidental, and 

 to believe that one brachial to each ray is the normal numl)er. 



The first anal plate is a little longer than wide, hexagonal, and 

 rests between the sloping sides of the two posterior subradials, and 

 partly under the left side of the right posterior radial. The second 

 anal is a little larger than the first, and rests on the upper margin of 

 the left posterior subradial. The third anal is smaller than the 

 others, and rests upon the first. 



Arms composed of rounded joints, not wedge-shaped, and divide 

 the second time on the eighth plate above the brachials, beyond 

 which they are simple in the posterior rays, the only ones visible 

 in our specimen. 



Column round, composed of short joints, and rather thicker at 

 the base of the calyx than below. 



Position and locality : Shaly sandstones of the Kinderbook 

 group, near Richfield, Ohio. 



Illinois State collection. 



POTERIOCRINUS CLYTIS, N. SP.. 



Body small, obconical, length and breadth at the top of the radial 

 plates about equal. Base truncated, the basal plates forming by 

 themselves a low pentagonal cup. Subradials about as wide as high. 

 Eadials pentagonal length and width apparently about equal, and 

 support on their upper margins a single series of long slender arm 

 plates, making but five arms to the entire animal. 



The first arm plates on the two rays that are shown in the speci- 

 men before me, are three or four times as long as wide, and above 

 these a series of ten or twelve shorter plates are preserved, all 

 rounded externally and generally longer than wide. The anal 

 plates are only partially preserved, but the form of the first can be 

 clearly seen. It is pentangular, and rests between two subradials, 

 and under the right posterior radial. Above this, part of a short 

 cylindrical ventral tube is preserved. Remains of short delicate 

 pinnules can be seen, attached to the inner borders of some of the 

 arm plates. 



Column rather stout, thicker at its junction with the body than 

 below, and composed of short even joints that alternate with thicker 

 ones below. 



This species differs in its arm formula from all other Pofcriocrin id (f 

 known at this time, and its departure from the normal structure 

 may prove of generic importance. 



Position and locality : St. Louis limestone, Monroe county. 111. 



Illinois State collection. 



