53 



Family SYNBATHOCRINID^ 



SYNBATHOCRTNUS ILLINOISENSIS, n. Sp 



Plate III, Fig. 29, basal side view of Calyx; Fig. 30, azygous 

 side view of same; Fig. 31, Summit view of same. 



Species from medium to large size. We have a specimen 

 about two-thirds as large as the one illustrated. Arms un- 

 known. Calyx truncated for a large column, broadly con- 

 stricted in the middle part, where it is evenly rounded, and 

 subpentagonal at the top, by reason of the straight, transverse, 

 superior sides of the first radials. About twice as wide as 

 high. Sutures slightly beveled. Surface granular. 



Basals form a cup three times as wide as high, having a 

 concave base for the attachment of a large column and a pen- 

 tagonal outline above for the support of the straight inferior 

 sides of the first radials. First radials one-third wider than 

 high, gradually expand from the base to the top which is 

 truncated the entire width, on three of the plates for the re- 

 ception of the second radials. The other two plates are 

 slightly truncated, at one angle, for the reception of the 

 azygous plate. Three of them, therefore, are quadrangular 

 and the other two pentagonal. The superior face of each 

 plate is very deep and bears an angular node, at each internal 

 angle, with a flange at the border of the internal cavity, 

 notched at the middle for the ambulacral furrow. There is a 

 straight furrow, half the width of the plate, just within the 

 outer margin, for the articulation of a ridge on the second 

 plate. The central cavity is pentalobate. 



The general form of the calyx of this species readily dis- 

 tinguishes it from all heretofore described. The rounded and 

 constricted body will alone suffice to separate it from all 

 others. It is not practicable, therefore, to compare it with 

 any other. 



Found in the Burlington Group, in Adams county, Illinois, 

 by C. S. Hodgson and now in the collection of S. A. Miller. 



