11 



than one-fourth as large as the first and extend about to the 

 top of the calyx. Each one is followed by a smaller plate 

 that abuts, each side, againsl a small plate, that covers pari 

 of the ambulacra! channel and in front unites with two 

 elongated plates belonging to the vault. 



The vault is very slightly convex, depressed in the inter- 

 radial arecis, toward the margin, so that each radial series 

 stands out prominently and bears a short subcentral proboscis. 

 The sutures between the plates are partly obliterated in our 

 specimen, so the artist has not attempted to show any of 

 the plates. There is a very small ovarian aperture close to 

 the ambulacral opening on each ^ide of each pair of arms and 

 on each side of each single arm, which gives to the species 

 twenty ovarian apertures. 



This species differs from D. bellulus, which it most resembles, 

 in many minor particulars and in some of specific importance. 

 It is smaller, shorter in proportion to its width, the radial 

 series stand out more prominently, at the summit, and the 

 vault is less elevated. The nodes are Longitudinally elongated 

 on the surface of this species, and transversely elongated on 

 D. bellulus, and the rest of the surface ornamentation quite as 

 different, notwithstanding the resemblance in some particulars. 

 In D. bellulus each of the arms adjoining the azygous area 

 bears four arms, in this species the right one bears four arms 

 and the left one three arms. In this species, the ray on the 

 Left of the series opposite the azygous area bears four arms. 

 and the corresponding ray in D. bellulus bears only three 

 arms. There are other differences but these are sufficient to 

 distinguish the species. 



Found by J. F. llammell in the Hamilton Group, near 

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

 ( rurley. 



DOLATOCRINUS CHARLESTOWNENSIS, n. sp. 



Plate III, Fig. 10, basal view; Fig. n. summit view; Fig. 12, 

 azygous side view. 



Species medium or above medium size and handsomely sculp- 

 tured. Calyx subhemispherical or subcylindrical, broadly trun- 

 cated at the base and constricted Widow the arms. Rounded 

 radial ridges have more or Less elongated nodes at the center 

 of the plates. Small ridges radiate from near the center of the 

 plates, bu1 they do not commence at the nodes or radial ridges. 

 A smooth space is left between the radial ridges and the com- 



