Carboniferous Rocks of the Mississippi Valley. 277 



narrow extensions between the first radial plates, as shown 

 in the specimen described). First radial plates forming 

 the base of the calyx, having the usual form of those of 

 this genus, but protruding in broad, sub-triangular nodes, 

 which give this apparent form to the plate. Second radial 

 plates quadrangular, small, much wider than high. Third 

 radial plates pentangular, the lateral faces very small, 

 short, and giving a triangular aspect to the plates ; these 

 support on each of their upper sloping edges a series of 

 two supra-radial plates, the upper one of which is wedge- 

 form, and supports the brachial plates on each side, giving 

 four arms to each ray. 



First interradial plate very large, equal to or larger than 

 the first radial plates ; two small plates in the second se- 

 ries, and sometimes a fourth plate above. Fu'st anal plate 

 heptagonal, and smaller than the first radials, supporting 

 three slightly smaller plates in the second range, with five 

 small plates arranged in an arch over the central one, and 

 one small plate below the brachial plates of the adjacent 

 rays. Surface of plates strongly nodose, the first inteiTa- 

 dials elevated into high rounded nodes ; the nodes of the 

 other plates are smaller and transverse ; entire surface 

 granulose. 



Of this species we have only the calyx below the arms ; 

 but the broad triangular projections of the first radial 

 plates, the depressed base, and the obscuring of the basal 

 plates by the column attachment, are peculiar features. 

 The basal plates are protruded along the suture lines of 

 the radial plates in narrow linear extensions, giving a 

 stelliform aspect to this part when the column is re- 

 moved. 



Geological formation and locality. Burlington lime- 

 stone, Burlington, Iowa. Collection of C. A. Wliite. 



Actinocrinus clarus (n. s.). Body very broadly sub- 

 tm'binate, spreading more rapidly above the thii'd radial 



