20 



Eadials pentagonal, wider than high, the articulating scar occu- 

 pying the entire width of the plate, with a well defined suture be- 

 tween the radial and brachial series. 



Brachials two to the ray on the anterior side, the first quadrangu- 

 lar, and the second pentagonal, sharply angular above, and support- 

 ing on its sloping sides the first divisions of the rays. On two of 

 the rays the arms bifurcate again on the sixth plate above the 

 brachial series, beyond which they are unknown. All the plates of 

 the body are finely rugose. Anal series unknown. 



Column slightly pentagonal where it joins the body, and composed 

 of alternate thin and thicker joints, but below more massive joints 

 are intercalated at short intervals. 



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

 saw, 111. 



Illinois State collection. 



POTEEIOCRINUS SPINOBRACHIATUS. N. SP. 



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

 to the top of the radial series. Base slightly depressed, the under 

 basals small and concealed by the first columnar joints. 



Subradials about as wide as high, the lower angles curved inward, 

 forming a part of the basal concavity. 



Eadials about one-fourth wider than long, pentagonal, -the upper 

 margins concave, leaving a gaping suture iDetween them and the 

 brachial plates. 



Brachials pentagonal, about as long as the radials, compressed 

 laterally, so as to form a rather prominent ridge across the middle 

 of the plate, ending at the upper angle in a rather obtuse point. All 

 the body plates, including the second radials, are marked Avith rugose 

 striations directed from above downward to the base, giving a rugose 

 appearance to the surface of the body. The brachials are sharply 

 angular above, and support the first arm plates, which are triangu- 

 lar, and one on each brachial is produced in front into a little node 

 that covers the projection at the summit of the brachial plates. 

 The succeeding arm plates are short, wedge-shaped, except the axil- 

 lary plates, which are longer than wide, and produced outwardly 

 into an obtuse point. All the other plates of the arms, where well 

 preserved, show short spiniferous nodes on their outer margins. 



The arms, after their first division on the brachials, divide again 

 on the eighth or tenth plate, and the outer division once or twice 

 more on the sixteenth to the twentieth plate, while the inner 

 branches continue single to their extremities. 



Column round, and near the top composed of short plates, the 

 alternate! ones projecting beyond the others. 



Anal plates unknown. 



This species is evidently ixdated to the crinoid figured by Yandell 

 and Shumard, in their "Contributions to the Geology of Kentucky," 

 without a description, but if their figure is correct, our species dif- 



