36 Cincinnati Society of Natural History. 



The summit is more or less convex in different specimens. From the 

 central pentagonal opening-, five double series of pseudoambulacral 

 pieces radiate to the angles of the pentagon. The number of pieces 

 seem to difl^er from fourteen to twenty or more in a single series, in 

 difterent specimens. A line of depression, commencing at the angle, 

 of the central pentagonal opening, separates each double series. The 

 pseudoambulacral pieces are removed from two of the rays and reveal 

 a long single piece or frame, extending from the angle of the central 

 pentagonal opening, to the angle of the pentagon, which has a ridge iu 

 the middle that separated the two series of pseudoambulacral plates. 



The specimen illustrated was collected by Mr. Dyer, in the upper 

 part of the Niagara Group, at Waldron, Indiana. 



EucALYPTocRiNus TDBERCULATUS, u. sp. (Plate II., fig. 9 and 9a.) 



i^iy .—Tubercitlattis, tuberculated ] 



The general form of the body is obconical, with a slight constric- 

 tion at the top of the first radial plates. The whole surface is strong- 

 1}^ tuberculated. Basal plates not observed. The first radial plates 

 are hexagonal and longer than wide. The upper end of each of these 

 plates is like the upper end of the first radials in E. crassus, but the 

 lower end is prolonged below the point of junction, with the column 

 instead of gently curving over into the pit for the column, or having a 

 truncated appearance, as in the latter species. The second radials are 

 somewhat quadrangular^ the width at the base being a little the great- 

 est. Three of the third radials are hexagonal, the other two are pen- 

 tagonal. The sides difl"er ver^^ little in length. The first supraradials 

 are either hexagonal or pentagonal, and about two thirds as large as 

 the third radial. The second supraradials are much smaller, and sup- 

 port on the upper sides a small triangular plate, upon which the first 

 arm-plates rest. The first interradials are large, nine or ten sided 

 plates. The two lower sides rest upon the first radials, the next two 

 are enclosed between the second radials, the next two between the third 

 radials, the two upper sloping sides between the undersides of the first 

 supraradials, and the two upper sides support two smaller interradials, 

 which are long and narrow, and extend up as high as the fourth or fifth 

 pair of arm-plates. This description applies to the two ten-sided in- 

 terradials, the other three have only nine sides, as shown by Plate II., 

 fig. 9, and difi'er in supporting one supraradial instead of two. The 

 inter supraradial plate is single, has nearh- the form of the two upper 

 inter-radials when united, and reaches nearly as high upon the arm- 

 plates. 



This species, in general form, resembles E. crassus, but is readily 

 distinguished by its large tubercles, and prolonged first radial plates. 



