278 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
tichal spaces. The plates marked by rounded ridges, one to each side of the 
plates; those upon the radials and fixed brachials much wider and more 
prominent. The ridges tapering to the margins of the plates, so as to form 
bead-like elevations along the rays, and a well defined star upon each inter- 
brachial. 
Basals large, forming an elongate cup, which is deeply grooved at the 
interbasal sutures, and the sides of the plates are bordered by conspicuous 
ridges, which are prolonged to the upper part of the radials. Radials and 
costals large, longer than wide; the radials larger than the costals. Dis- 
tichals two. Palmars free from the fourth plate. Arms twenty, simple, 
long, slender, gradually tapering to their tips, and beyond the fourth or fifth 
plate strictly biserial. The first pinnule is given off from the second pal- 
mars, and all succeeding brachials are pinnule-bearing. Interbrachials: 1, 2, 
2, 2, 2, ec.; the lower one considerably the larger. Interdistichals: 1, 1, 1; 
interpalmars: 2 to 3. Anal interradius the widest, the lower plates some- 
what larger than the corresponding plate of the four other sides. It con- 
tains three plates in the second and all succeeding rows, the middle series 
marked by a somewhat interrupted longitudinal ridge. Similar but shorter 
ridges proceed from the first anal plate to adjacent radials. Construction of 
ventral disk, and position of anus not known. Column slightly decreasing 
in size downward; round; composed of rather long joints with convex 
edges; the nodal joints considerably thickest. At three inches from the 
calyx, each internode contains seven to eight joints, of which every second 
or third is nearly as large as the nodal ones. 
Florizon and Locality. —Trenton limestone, Ottawa, Canada. 
Types in the Canada Survey Museum at Ottawa; collected by Mr. John 
Stewart. 
We take pleasure in dedicating this elegant species, the type of a new 
genus, to our friend Mr. Walter R. Billings, the author of several important 
papers on Crinoids, to whom we are indebted for many favors. 
Periglyptocrinus priscus (Brcuines). 
Plate XXTI. Fig. 2. 
1856. Glyptocrinus priscus — Vi. Bruurncs; Geol. Surv. Canada (Rep. of Progress), p. 287; also 1859, De- 
cade LV. p. 56, Plate 7, Figs. la, 4, ¢. 
1881. Glyptocrinus priscus —W. and Sr.; Revision Paleocr., Part IT., p. 189. 
1883.  Glyptocrinus priscus —S. A. Mituer; Journ. Cincin. Soe. Nat. Hist., p, 225. 
1883. (?) Archeocrinus priscus — W. and Sr.; Revision Paleocr., Part III., p. 301. 
