138 Cincinnati Society of Natural Histori/. 



group resting upon the second radials, the others upon the outer ex- 

 tremities of the first radials. 



Brachials — Sixty, in series of threes over the third radials, which 

 the3' resemble in size and form, except that the upper one is slightly- 

 wedge-shaped. 



Arms — Twenty, in groups of fours between the interbrachial raj's, 

 composed, as in the other species, ofa double series of interlocking plates, 

 each of which bears a stout pinnule. The arms are large enough to 

 fold over to the central space between the bases of the interbrachial 

 rays, and graduall}' taper to their extremities. 



Interbrachial rays — Five, somewhat thickened above, much thinner 

 on the inferior side, also thickened at the proximal, and very much at- 

 tenuated at the distal extremities. 



They are ^'ery much excavated, centrally, on the ventral or upper 

 side, giving this surface a concave outline, while they are slightly con- 

 vex below. The extremities are rounded, and the outer half of the ray 

 has the closest resemblance to the blade of a spatula. The rays are 

 articulated to the five angles of the vault, as shown in my review of 

 this genus, and are a part of it 



The upper part of the vault, in all the specimens, is covered b}^ a 

 Gasteropod, the shape of the shell accommodating itself to the space at 

 the base of the rays. 



Column — Very slender, round, and composed of thin plates, there 

 being fourteen in three eighths of an inch. 



The specimens from which this description has been drawn are all 

 somewhat crushed, and the exact proportions of the body are difficult 

 to determine. But it is much wider than high, and this depressed form 

 arises from the shape of the plates as above described. 



From all species of the genus hitherto defined, this one difi^ers in the 

 form of the interbrachial rays. 



Locality and position: In rocks of the Kaskaskia (Chester) Group, 

 sub-carboniferous, Pulaski county, Ky. 



FORBESIOCRINUS PARVUS, U. Sp. 

 Plate XL, fig. 4a azygos, 46 opposite side. 

 Basals — Three, triangular, thin, and having their articulating su- 

 tures covered by the first section of the column. Though the generic 

 formula of this genus, as established by its illustrious authors, has 

 been modified by calling these pieces basals, I am much in doubt as 

 to the propriety of such a conclusion. It is likely that a careful study 

 will show the column to be thus divided for some distance below the 

 body. 



