i di 
S. S. Lyon and S. A. Casseday on new species of Crinoidea. 69 
The vault is divided into five triangular spaces by the wings, five in 
number; each space is covered with seven pieces of a compressed hex- 
agonal form, three rising from the arms from the first row; upon these 
rest two; in the angular space at the summit of these rests the sixth, 
similar in size to those below it; it is squarely truncated above, thus be- 
coming pentangular; its upper margin supports a small quadrangular 
piece; there are some quite small pieces above this last, in our specimen, 
probably one row which may forin the mouth; between each of the five 
fields of the vault is a long lanceolate piece as wide as the other pieces of 
the vault; and about three times as long as those in the fields; the wings 
margins nearly parallel; obtusely rounded at their outer extremity. 
he arms are single, twenty in number, lying in sets of four between 
the wings, which, being placed immediately above the centre of the first 
radials, divide them into pairs, two from each of the adjacent radials fall- 
ing into the spaces between each pair of wings. The arms are provi 
with a row of cilia for each side, formed of short joints, placed immedi- 
ately in contact one above the other, filling the length of the arms which 
rise above the wings, about one sixth of their length. e dermal,coat- 
ing has been lost from all the specimens we have seen. The sides of the 
pee ue strongly marked by a muscular attachment, by which they were 
Oved, (¢ 
By reference to the figures it will be evident that this differs from all 
heretofore described species; by the bipartite basal pieces it is related to 
Dichocrinus, 
Dimensions of Specimen of Medium Size. 
Height of base, ‘20 inches. 
“ [74 vau °30 “ 
; ule See : é : 
Diameter of arms, - - - - 75S 
Length of * - - - - i 
Greatest width across the wings, - se 6 * 
Height from base to top of wings, —- - 8 a ON 
: Geological Position and Locality.—Several specimens have been found 
in the third intercalated limestone, of the Millstone grit, Grayson Springs, 
Grayson County. Same horizon, near Dr. Baker’s furnace, Edmonson 
County, Ky. : 
Pterotocrinus pyramidalis, sp. nobis. 
