OcT., 1907. New CRINOIDS — SLOCoM. 279 
into the basal cavity. The three plates at the angles are larger than 
the other two. The basal triangle is followed by three large plates 
which comprise the principal part of the calyx. These are the an- 
terior and left posterior radials and an inferradial plate. The left 
posterior radial rests upon two basals, the other two plates rest upon 
three. The other three radials are small, angular below and are not 
in contact with the basals; the left anterior radial rests upon the 
sloping sides of the adjoining radials, and the right posterior and 
right anterior radials each rest, one side upon the inferradial and one 
side upon the adjoining radial. The distal edges of the radials are 
provided with short processes at their juncture with the lateral edges 
which form a wide, shallow, angular excavation for the attachment 
of the arms. 
Arms not preserved. 
Owing to the thickness of the plates, the natural casts of this genus 
bear little resemblance to the exterior of the calyces. The natural casts 
of this species are in the form of a triangular pyramid, truncated by a 
cylinder. The base of the pyramid is nearly flat and is formed by the 
inner surfaces of the basal plates. One face of the pyramid is formed 
by the inferradial plate and the other two by the lower part of the 
large radials. The cylinder is formed by the three small radials together 
with the upper part of the two larger ones. 
The distinguishing characteristics of the exterior of the calyx of 
this species are its globular form, with its depressed base, gradually 
curving into the facet for the attachment of the stem. The casts are 
distinguished by the triangular pyramid at its base. , 
Locality: This species is comparatively abundant in the clay 
pockets in the limestone at Romeo, Illinois, where it occurs as silici- 
fied specimens which appear to be identical with those of the type 
locality. Inthe spoil heaps along the Chicago Drainage Canal near 
Lemont, Illinois, it is one of the most abundant crinoids in the form of 
naturai molds and casts, and a single silicified specimen was found 
there. 
PISOCRINUS BENEDICTI S. A. Miller, Plate LX XXIV, Figures 8-11. 
1892. P. benedict S. A. M., 17th Rept. Geol. Surv. Ind., p. 639, 
Pl. VI, Figs. 3-16. 
Calyx deeply cup-shaped, moderately expanding to the upper 
third, rounded at the base and slightly constricted at the top; plates 
thick, surface smooth or finely granular. 
The plates of the calyx are the same in number and position as 
in P. gemmiformis, but the basals are larger than in that species, so as 
