INYEKTEBKATES. 311 



Column round, very strong at the base of the calyx, decreasing 

 about one-half in diameter a half inch below, and composed of rather 

 thin, even joints. 



Position and locality: Kinderhook group, Marshalltown, Iowa. 



The author's collection. 



GENUS EUPACHYCRINUS, Meek andWorthen. 



EUPACHYCKINUS ASPERATus, Worthen. 



PI. XXIX. Fig. 4. 



Eupachycrinus aaperatus, WOETHEN, February, 1882. 



Bulletin No. 1, of the Illinois State Museum of Natural History, p. 34. 



Body of medium size, basin-shaped, composed of very massive 

 angular plates. Base deeply concave and basals concealed by the 

 column. 



Subradials very massive, projecting outward and downward, 

 slightly excavated below from their outer sides to the point where 

 they join the basals, and forming five prominent angular nodes on 

 which the body would rest when divested of its column. 



Kadials nearly twice as wide as long, four of them pentagonal, 

 the right posterior one quadrangular, and all produced into obtuse 

 nodes or ridges that on three of them extend nearly across the plate, 

 nearer to the lower than the upper margin, leaving a broad, sloping 

 surface between the ridges and the upper margin of the radial 

 plates. 



Brachials on each of the anterior and the antero-lateral rays, 

 shorter and about the same width as the radials, and like them 

 produced into a distinct ridge on their upper margins. 



The right posterior brachial supports two shorter brachials, and 

 these support above two arms each, making four arms to this ray. 

 The left posterior brachial supports an additional brachial on one 

 side, that gives support to two arms, while a single arm is supported 

 on the other side, making three arms to this ray. The other 

 brachials give support to two arms each, making thirteen altogether 

 for this species. The first three or four plates of each arm are quad- 

 rangular, but they soon pass into a series of wedge-formed interlock- 

 ing pieces, gradually becoming narrower toward their extremities. 



