a _ = ——E7E — 
684 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Platycrinus subspinulosus Hatt. ie 
Plate LX VI. Figs. 2a, b, ond Plate LX X. Fig. 9. 
1860. Hazn; Suppl. Geol. Rep. Iowa, p. 81, with diagrammatic figure. 
1881. W. and Spe.; Revision, Part II., p. 75 (Proceed. Acad. Nat. Sci. Phila., p. 249). 
Below medium size. Height of dorsal cup about equal to the width at 
the lower edges of the radial facets, where the section is distinctly quinque- 
lobate, owing to a thickening of the radials at the median line toward the 
facets. Plates thin at their edges, but quite heavy at the middle; covered 
with short spines or conspicuous nodes, which upon the basal cup are quite 
irrecularly distributed, some of them being thickly set and confluent, others 
dispersed, especially in the upper portions of the cup. The spines upon the 
radials are arranged in three rows, two of them proceeding from the facets 
diagonally to the lower angles of the plates, the other vertically to the basal 
cup. Interradial sutures at the bottom of a shallow angular depression, not 
grooved ; interbasal sutures obsolete. 
Basal cup subcylindrical, a little widest at the upper end; the column 
facet projecting and distinctly elliptic. Radials slightly spreading, nearly 
once and a half as long as wide; the facets horse-shoe shaped, longer than 
wide, profoundly excavated, and having a deep, rounded notch at the upper 
end. Structure of arms and ventral disk unknown. 
Horizon and Localty.— Upper Burlington limestone, Burlington, Iowa. 
Type in the Illinois State Museum of Natural History. 
Platycrinus Davisi W. and Sp. (nov. spec.). 
Plate LXX. Fig. 1. 
Below medium size. Dorsal cup depressed bell-shaped, a little wider 
than high, rounded at the base, the sides concave along the basal cup, con- 
vex along the radials. Plates rather heavy; the suture lines very slightly 
grooved. 
Basal cup deep, wide at the bottom, its height equal to two thirds the 
length of the radials, its lower face quinquelobate, having five short, rounded 
nodes, interradially disposed and extending over the whole width of the 
plates; they are separated by.a well defined groove, giving to the base the 
appearance of being quinquepartite. Attachment for the stem circular and 
