632 STUART WELLER 
species differs from the other members of the genus here described 
in its subhemispherical form, all the others being turbinate. 
CIBOLOCRINUS TURBINATUS N. Sp. 
(Plate I, Figs. 23-26) 
Description Dorsal cup turbinate, the sides diverging with a con- 
vex curvature from the margin of the columnar facet to the distal 
margins of the radial plates, surface of the plates smooth, the sutures 
not impressed in grooves. ‘The dimensions of a complete dorsal cup 
are: diameter 25™™, height 17™™. Underbasal plates three in num- 
ber, one small one anteriorly and two large ones posteriorly, a little 
more than one-third of the length of each plate at the proximal end 
is covered by the columnar facet which is in the form of a conelike 
depression, the exposed distal portions of the plates form the flaring 
sides of a shallow cup. Basal plates large, the right and left postero- 
lateral ones nearly symmetrically pentagonal in outline, the two anterior 
ones hexagonal but with the two proximal faces meeting in a very 
wide angle so as to form nearly a straight line, the two faces together 
being equivalent to the single proximal face of the postero-lateral 
plates, the posterior plate similar to the two antero-lateral ones but 
with the distal angle truncated to support the anal plate. Radial 
plates nearly twice as wide as high, pentagonal in outline, their sur- 
face curving a little inward near the distal margin, their distal faces 
bearing strong articular ridges. Anal plate small, resting between 
the posterior radials upon the truncated distal extremity of the pos- 
terior basal, widest between the posterior distal angles of the radial 
plates on either side, probably pentagonal in outline though the distal 
portion extending beyond the level of the radials is imperfect in the 
type specimens. 
Remarks.—This species is established upon two individuals, both 
preserving only the dorsal cup. The most perfect one has exactly 
the same structure of the dorsal cup as C. typus, the two species 
differing in form and proportions. The second less complete example 
has the sutures between the underbasal plates obscure, but they seem 
not to have the same position in the first specimen. ‘The normal 
position for these sutures, in this and other species of the genus, is 
beneath the posterior and the two antero-lateral basal plates, those 
