106 
Kirtley F. Mather 
longitudinally, moderately convex transversely, nearly twice as 
wide as high, truncated and faceted above for the attachment 
of the primibrachs; anal plate small, pentagonal, nearly three 
times as long as wide, resting upon the truncated angles of the 
two posterior radials and situated in the main above the radials, 
only the lower one-fourth of its length being within the dorsal 
cup, its surface sloping strongly toward the center of the ventral 
sac, and reclining at an angle of about 45° with respect to the 
axis of the calyx; arms and ventral sac unknown. 
The dimensions of the individual selected as the holotype are : 
outside diameter of dorsal cup, 15.8 mm.; diameter of peri- 
phery of upper margin of dorsal cup, 13.4 mm. ; diameter of 
body cavity, 7.4 mm. ; height of dorsal cup, 5.5 mm. 
Remarks. The generic relationships of this crinoid, the most 
abundant one in the Morrow collections, are not altogether clear. 
In general form and because of the deep funnel-like concavity 
of its base, its affinities seem to lie with the members of the 
genus to which it has been referred, but the position of the 
anal plate which misses contact with the posterior basal by 
about 0.3 mm. is unlike that of the species referred with cer- 
tainty to Delocrinus by Miller and Gurley^^. In the latter forms 
the posterior basal is truncated for the attachment of the anal | 
plate which is situated between the posterior radials. The rela- j 
tionship of D. dubius to Erisocrinus? planus White, the generic 
position of which is also in doubt, is probably very close. 
Horizon and locality. Brentwood limestone: near Fayette- 
ville, Arkansas (Stations 134, 135, and 153). Morrow forma- 
tion: near Ft. Gibson, Oklahoma (Stations 296 and 301). 
Delocrinus pentanodus n. sp. 
Plate III, figures 8-8b; text figure 3. 
Description. Dorsal cup small, low, basin-shaped, with 
slightly concave base and no constriction at upper margin of 
radials; infrabasals five, suture lines scarcely discernible, pro- 
jecting well beyond the shallow circular depression of the stem 
attachment ; basals five, pentagonal in outline, the posterior basal 
hexagonal because of truncation for the anal plate, gently con- 
vex transversely and longitudinally throughout the greater part 
of each plate but abruptly deflected upward near the acute outer 
