628 STUART WELLER 
men are: diameter of dorsal cup 20™™, height of same 7™™. Under- 
basals situated in the bottom of the basal excavation, the diameter 
of the underbasal disk being about 5.5™™, the columnar facet cir- 
cular, its diameter about one-half the diameter of the underbasal 
disk. Basal plates large, longer than wide, the proximal portion 
forming the sloping sides of the basal excavation, the distal portion 
sloping outward and upward, the distal extremities angular in all 
except the posterior plate which is truncated for the reception of the 
anal plate. Radial plates large, about twice as wide as high, pen- 
tagonal in outline, their distal faces furnished with strong articular 
ridges. Anal plate small, resting between the posterior radials upon 
the truncated distal extremity of the posterior basal, pentagonal in 
outline, the distal extremity angular and extending somewhat beyond 
the level of the radials. 
Remarks.—This species is based upon a single very perfect dorsal 
cup which is similar in size to D. hemisphericus (Shum.). It differs 
from that species, however, in the larger underbasal plates, the 
broader basal excavation, and in the convexity of the plates, the 
surface of D. hemisphericus being even throughout with the sutures 
flush with the general surface. 
DELOCRINUS EXCAVATUS Nl. Sp. 
(Plated: Figs. 16; 17) 
Description.—Dorsal cup basin-shaped, deeply and broadly exca- 
vated at the base, the plates a little convex, the sutures impressed in 
shallow grooves. The dimensions of a dorsal cup are: diameter 
20™™, height 7™™. Underbasal plates entirely included in the basal 
excavation which in the type specimen has a diameter of 8™™ at 
its margin and a depth of 3™™ or more, with nearly vertical sides. 
Basal plates rather large, their proximal borders incurved to form the 
sides of the basal excavation, the distal extremities angular except 
the posterior one which is truncated to support the anal plate. 
Radial plates large, much wider than high, pentagonal in outline, 
their distal faces furnished with articulating ridges. Anal plates two 
in number, together occupying the position of the single anal plate 
which is commonly present in this genus, upon the truncated distal 
extremity of the posterior basal, the two plates are of nearly equal 
