22 



This species is distinguished, by its general form; by the beveled 

 plates of the calyx; by the azygous area aud eighteen arms. There 

 is no species with which it is necessary to make any comparison. 



Found in Keokuk Group, in Washington county, Indiana, and 

 now in the collection of Wm. F. E. Gurley. 



ACTINOORINUS BOTRUOSUS, n. sp. 



Plate 2, Fig. 1, azygous side; Fig. 2, opposite side of the same 



specimen. 



Species robust, above medium size. Calyx nearly as long as 

 wide. Radial series prominent aud inter-radial areas depressed so 

 as to give it an ob,)yramidal form or sub-pentagonal outline to a 

 transverse section. Plates tliick, tumid, and each one bears a cen- 

 tral node, which, on the larger plates, is elongated transversely. 

 The rays are abruptly expanded above the third primary radials, 

 leaving the inter-radial areas depressed, thus forming projecting 

 clusters of each of the five radial series and directing the ambulacral 

 openings nearly horizontally. The sutures are interrupted by 

 radiating sculptures, that are so short that the sutures appear as 

 if pitted. 



Basals a little wider tliau high, very thick, contracted in 

 the middle and at the upper part so as to leave an expanded rim 

 projecting much beyond and below the point of attachment with 

 the column aud having widely gaping sutures below so that the 

 calyx will stand on the projecting aud contracted ends of the basal 

 plates. Column round, radiately furrowed, and having a diameter 

 a little more than one- third the greatest diameter of the expanded 

 basals. First primary radials large, rather longer than wide, three 

 hexagonal aud two heptagonal. Second primary radials wider than 

 high, hexagonal, and more than half as large as the first. Third 

 primary radials as large as the second, heptagonal, aud support- 

 ing upon each of the superior sides a single secondary radial which 

 is axillary, aud supports upon each of its superior sides two ter- 

 tiary radials, the last of wlijch is axillary and supports the free 

 arms, in all the rays that are preserved to show that extent of 

 development in our specimen, tliough some of the rays do not 

 preserve the first arm plates. If the arms are alike, therefore, in 

 these four rays there are eight to each one. In the ray opposite 

 the azygous area, on one side of the tiiird primary radial, there is 

 a single secondary plate, which is axillary and supports on each 

 upper side two tertiary radials, and on the other side there are 



