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POTEBIOCEINUS FOUNTAINENSIS. N. SP. 



Body under medium size, rapidly spreading from the base to the 

 top of the radial series, where it is about twice as wide as high. 

 Basals small and concealed by the first columnar joints. Subradials 

 hexagonal and heptagonal, length and breadth about equal. Eadials 

 once and a half as wide as long, pentagonal, with a well defined 

 suture between them and the brachial plates. Brachials about 

 twice as long as wide, pentagonal, and narrower in the middle than 

 at the ends and supporting two arms on their upper sloping sides, 

 the brachial on the anterior ray being longer and more constricted 

 than the others. Arms apparently but two to the ray, and composed 

 of long zigzag joints, constricted in the middle and giving off on alter- 

 nate sides from their upper angles strong pinnules, that are about 

 half as large in diamater as the arms. 



The first anal plate is nearly quadrangular in form, and rests be- 

 tween two of the subradials and under the left side of the right pos- 

 terior radial. The second aiid third are a little smaller than the first, 

 and above these there is a double series of small plates that extend 

 up to the base of the ventral tube. 



This species is rather closely related to Pot. (Scajih.) inteimodius 

 of Hall, Iowa Keport, part 2, but differs from that in the form and 

 proportions of the plates of the body, and in the zigzag arrangement 

 of the arms. 



Position and locality : St. Louis limestone, Fountain creek, Mon- 

 roe county. 111. 



Illinois State collection. 



POTEKIOCRINUS TALBOTI. N. SP. 



Body very short, basin shaped, base depressed, and the basals hid- 

 den in the basal concavity. 



Subradials short, curving inward below to form by their lower 

 angles part of the basal depression. 



Eadials pantagonal, twice as wide as high, widest at their upper 

 margins, and truncated squarely across for the reception of the 

 brachial plates. 



On the anterior ray there are six or seven brachials, all becoming 

 narrower upward so that the last is only about half as wide as the 

 first. The last one is an axillary plate, and supports two arms 

 that continue simple to their extremities. The other rays have but 

 a single brachial, which is as large or larger than the radials on 

 which they rest, pentagonal in form, and give support on their upper 

 sloping sides to the first divisions of the rays. On the left antero- 

 lateral ray the arms divide on the sixth plate, beyond which they 



Note. — The ScapJiiocrinus decahrachiatxs, S. inter no dius, S. scoparius and Zeacrinus 

 intennedii/f;. described by Hall in the Iowa Report, part 2, were collected by the writer, 

 and were all from the St. Louis limestone and not from the Chester group, a tact that 

 it is necessary to bear in mind in the identification of these species with those from 

 other localities. 



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