47 



radials, which gives to this ray two arms. There are, there- 

 fore, sixteen arms in this species. The arm formula is 4+3+ 

 2+4+3. 



The azygous area is substantially like the others. The first 

 interradials are the largest plates in the calyx, have nine sides 

 and are broadly truncated for the second interradials. The 

 second interradials are more than half as large as the first, 

 and are followed by three plates in the third range, the middle 

 one only abutting upon the third ones, while the lateral ones 

 form part of the covering for the ambulacral channels. The 

 third range unites with two elongated plates belonging to the 

 vault. 



The vault is only slightly convex, and is covered with a few 

 large nodose plates. The azygous orifice is at the summit of 

 a short elevation, at the central part of the vault. There are 

 twenty small ovarian apertures. 



This species is distinguished from all other sixteen-armed 

 species by its general form and surface ornamentation, and 

 also from all of them by the arm formula. For example, the 

 arm formula in D. ccelaius is 4+4+4+2+2, in D. nodosus it is 

 4+3+3+3+3, in D. salebrosns it is 4+3+2+3+4, in D. ham- 

 melli it is 4+3+3+3+3, and in D. arrosus it is 4+4+3+3+2. 



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

 Charlestown, Ind., and now in the collection of Wm. F. E. 

 Gurley. 



DOLATOCRINUS ASPER, n. Sp. 



Plate HI; Fig. 10, basal view; Fig. 11, summit view; Fig. 12, 



azygus side view. 



Species medium or rather below medium size. Calyx sub- 

 hemispherical, broadly truncated, and constricted below the 

 arms. Radial ridges small, sharply angular, and bear a lon- 

 gitudinal sharp node at the middle of each plate. Ridges ra- 

 diate from a node at the center of each plate. Column round 

 and bears a cinquefoil central canal. 



Basal plates form a hollow cone within the cavity of the 

 calyx. The column fills the cone so that the diameter of the 

 column is nearly equal to the diameter of the pentagonal basal 

 disc. First primary radials nearly or quite as long as wide 



