22 Cincinnati Society of Natural Fitstory. 
vault, and bearing fine longitudinal lines in the middle and lower 
central part, and transverse lines on each side of these on the 
upper part; the succeeding plates cover a moderately convex 
ridge, expanded a little above the other part of the vault which 
extends to the side of a central nipple occupying the summit of the 
vault, and at the junction there is a valvular opening, but it is not 
connected with the central elevation; this nipple-like elevation 
is covered with very small polygonal plates, and from the lower 
part of it five ambulacral ridges radiate to the second and third 
radials, which ridges are covered with minute polygonal plates. 
The column is round and composed of thin plates with sharp pro- 
jecting edges. 
Found in the Kinderhook or Waverly Group, at Le Grand, 
Iowa, and now in the collection of Wm. F. E. Gurley. 
POTERIOCRINUS GRANILINEUS, N. Sp. 
Plate IV., Fig. 7, natural size. 
Calyx low, basin-shaped; sutures well defined; basals small 
and hidden by the column; subradials small, hexagonal, except 
one on the azygous side, which is truncated at the top and heptag- 
onal ; first radials wide, short, pentagonal, and truncated on top, 
where they have their greatest width ; second radials quadrangular, 
short, wider than the first, and having the greatest width at the 
upper truncated surface; third radials wider than the second, pen- 
tagonal, very short, with steep upper sloping sides, which are 
slightly curved to receive the free arms; arms short, composed of 
short cuneiform plates, so strongly arched in the middle as to form 
a subangular ridge down the back of all the rays, on which the 
granules are so united as to form a keel; all the arms preserved in 
our specimen (six in number) bifurcate on the sixth plate, and 
above this the bifurcations are irregular, one of them bifurcating 
on the fourth plate, and others do not seem to bifurcate at all; the 
arms are flattened so as to fit closely together as in Zeacrinus; 
pinnules not observed; the first azygous plate is inserted obliquely 
between a subradial and the under sloping side of a first radial, 
with the truncated lower end resting against another subradial ; this 
plate is pentagonal ; the second azygous plate rests upon the first 
above-mentioned subradial, and between the radials on the left and 
