II 



The vault is slightly convex toward the central part and 

 equally as much depressed in the interradial areas toward the 

 margin. The plates are large, but the sutures are too indis- 

 tinct, in our specimen, to allow the artist to trace them, be- 

 sides, the surface is so eroded as not to preserve the surface 

 ornamentation. The subcentral azygous orifice is excentric 

 from the azygous side, which is well shown in figure 2 and 

 presents a peculiarity rarely seen in a crinoid. There are 

 twenty ovarian pores situated close to the ambulacral open- 

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

 each side of the single arm openings. 



The arrangement of the arms, in this species, is different 

 from that in D. Iicllulits and D. aureafus, where each of three 

 rays bear three arms and the other two bear four arms each, 

 beside important differences in form and surface ornamentation. 

 These are the only species that have been described that bear 

 seventeen arms, and it is quite unnecessary, therefore, to make 

 further comparisons. 



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

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

 Gurley. 



DOLATOCRINUS ARGUTUS, 11. Sp. 



Plate III, Fig. 1, basal view; Fig. 5, azygous side; Fig. 6, summit 



view. 



Species rather below medium size. Calyx bowl-shaped, sub- 

 pentagonal, concave below; radial ridges broadly rounded; 

 plates highly convex and slightly radiately ridged toward the 

 margins. Column small and round. 



Basal disc pentagonal, depressed; the basal plates are within 

 the cavity of the calyx, in the form of a hollow cone, and the 

 end of the column fills the hollow cone in the superior part, 

 and leaves the basal disc, at the base of the cone, one-half 

 wider than the diameter of the column. First primary radials 

 about as long as wide, abruptly bent in the middle, the lower 

 pari forming part of the basal concavity and the superior part 

 curving as abruptly upward. The central part of the plates 

 are tumid rather than nodose and the calyx will rest on the 

 tumid elevations. Second radials quadrangular, a little wider 

 than long and sides nearly parallel. Third primary radials 

 about twice as wide as high, rather smaller than the second 

 primary radials, pentagonal, axillary and support upon each 

 superior sloping side two secondary radials. The second sec 

 —6 



