39 



ten sides. It is followed by two elongated plates in the second 

 range, beyond which we have been unable to see the sutures. In the 

 inter-secondary areas one plate is followed by two in the second 

 range, and those by three in the third range, beyond, which silici- 

 fication has destroyed the sutures in our specimens. 



The vault is low. but our specimens are not preserved to throw any 

 Light upon it. 



The greater number of specimens are found silicified, and it is 

 rare to find the crinoidal structure exposed. It is a remarkable spe- 

 cies and bears little or no resemblance to the type species. Indeed 

 no one would suspect that they could belong to the same genus, 

 without having compared them with the generic formula. The two 

 primary radials in each species alone ally them with each other. 



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

 town, Indiana, and now in the collection of Wm. F. E. Gurley. 



Family RHODOCRINID^E. 



RHODOCRINUS DOUGLASSI, n. Sp. 



Plate III, Fig. 1, azygous area on the left. 



Species medium or above medium size. Calyx bowl-shaped, or 

 subcylindrical. radial ridges not defined. Plates sculptured and 

 more or less pyramindal. Basal cavity deep. Column medium size, 

 round, and composed of plates of equal length. 



Basals form a cone, within the calyx, into which the end of the 

 column is inserted. Subradials slightly larger than the first primary 

 radials and sculptured pyramidal. First primary radials pyramidal, 

 heptagonal and hexagonal. Second primary radials about one fourth 

 as large as the first, nearly as long as wide, pentagonal. Third prim- 

 ary radials about the size of the second, hexagonal, and sup- 

 port on each of two upper sides, the secondary radials. There are 

 three secondary radials in each series, the first one being the larger 

 and the last one being axillary. There is a plate, resting in the 

 angle, formed at the juction of the first secondary radials. which 

 has the appearance of belonging to a radial series and the third 

 plate above being axillary. But here an explanation becomes neces- 

 sary. Our specimen is injured, at this place, as shown in the illus- 

 tration, and we cannot determine exactly how the arms attached. 

 The ray we are describing is on the right of the azygous area and 



