84 



Cincinnati Society of Natural History. 



much the smaller of the three, and supports upon the upper sloping 

 sides a pair of secondary radials. 



The secondary radials are small, and support the arm-plates, which 

 are not preserved in our specimen. 



Interradials. — Regular interradials, three. The first is heptagonal, 

 about the size of the basals, and wider than long. It supports the 

 other two, which are much smaller, and are followed b}* two inter- 

 brachials that connect with the plates that cover the vault. The first 

 azygous interradial is a large octagonal plate. It is succeeded by 

 three interradials, instead of by two, as in the other interradial areas. 

 These are followed b} T polygonal plates of unequal size, that are con- 

 tinued to the proboscis. 



The vault is covered by numerous polygonal convex plates of un- 

 equal size. The arms are arranged in five pairs, each pair being much 

 closer together than they are in the other species of this genus. The 

 column is unknown. 



In Lyriocrinus melissa (Hhodocrinus melissa), from Waldron, In- 

 diana, the third radial is hexagonal, being truncate at the top, and 

 supports an intersecondaiT plate, which is not the case in this species. 



This species I received from Tennessee, labeled from the Niagara 

 Group, though it ma}- possibly be from the Lower Helderberg. It is 

 such a marked species, that it will be readily distinguished without 

 the special localit}' from whence it came. 



Endoceras egant, n. sp. 



Plate IV., fig. 1, ventral view of the siphuncle and the interior tube a short distance be- 

 low its apex, where it nearly fills the cavity of the siphuncle: the dotted line shows the 

 swelling of the siphuncle at the commencement of the internal tube: fig. la shows the point 

 of the internal tube and its rapid wedge-shaped expansion: fig. lb is the other part of the 

 same specimen, as the two pieces are broken, and shows the swelling of the siphuncle within 

 the chamber at the place where the internal tube arises. 



This species is founded upon the siphuncle and the internal tube, 

 the external appearance of the outer shell being unknown. The si- 

 phuncle is long and very slightly tapering. The marks of the septa 

 are distant, and cross the siphuncle diagonalh', inclining toward the 

 apex on the ventral side, at an angle of from 20 to 30 degrees. The 

 diameter of the siphuncle, at the place at which the internal tube 

 arises, is a little less than an inch, and the septa are distant nearly 

 one half an inch. 



The internal tube arises near the ventral side, and rapidly enlarges 

 into a half wedge- shape, or a tube convex on one side and flattened on 



