ft 



44 



with two elongated plates belonging to the vault, and in each 

 of the other areas by a single plate, in the fourth range, that 

 unites with two elongated plates belonging to the vault. 



The vault is moderately convex, and covered with a few 

 large polygonal plates. The azygous orifice is subcentral and 

 slightly elevated above the surrounding convexity of the vault, 

 as shown in the illustrations. The specimen is complete, ex- 

 cept there may have been small plates that covered the orifice 

 itself. The plates covering the vault are coarsely granular, 

 and those over the junction of the ambulacral canals bear 

 small nodes. There are two elongated plates in each inter- 

 radial area, and, within these, a circle of seven plates sur- 

 rounds the base of the elevation for the azygous orifice. There 

 are twenfy ovarian pores situated close to the ambulacral 

 openings; one on each side of the double arm openings and 

 one on each side of the single arm openings. 



This species is distinguished from Dolatocrinus indianensis, 

 which it most resembles, by having one more range of inter- 

 radial plates in each area, and one more plate in each tertiary 

 radial series, and one more plate in each three secondary ra- 

 dial series. This arrangement lengthens the calyx correspond- 

 ingly and adds to the radials in the calyx seventeen plates, 

 and to the interradials six plates, as the fourth range, in one 

 of the areas, contains two plates. Other differences in the two 

 species seem to us to be of minor importance, but these, taken 

 together, are of specific value, as we understand the structure 

 of crinoids, in this genus 



Found by Geo. K. Greene, in the Hamilton Group, near 

 Charlestown, Indiana, and now in the collection of Win. P. E. 

 Gar ley. 



DOLATuCKINUS LYON J, 11. Sp. 



I '/ale I I I, Fig. 4, summit view; Fir/. 5, hasa! view; Fig. (1 uzy- 



gous side vi< ir. 



Species medium size. Calyx subhem i spherical , broadly trun- 

 cated and slightly constricted below the arms. Radial ridges 

 small, angular nodes at the center of each plate, sharp and 

 elongated. Surface of each plate ornamented with numerous 

 fine lines radiating from a sharp central node. Column medium 

 s'.ze, round and having a very large cinque foil canal. 



