ad Sane 
a 
Se 
apne —— 
764 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
striz vertically arranged, and all continued to the basals, where the corre- 
sponding ones meet with those from adjoining radials at acute angles; the 
striz in well preserved specimens showing a rhombic arrangement. 
Basal cup rather flat, presenting a shallow basin; the columnar attach- 
ment very small. Radials a little longer than wide; the lower faces a little 
convex; facets shallow, occupying about one half the width of the plates. 
Structure of the disk and arms unknown. 
Horizon and Locality. — Lower Burlington limestone; Burlington, Iowa. 
Lype in the Museum of Comparative Zoblogy. 
Dichocrinus cinctus Mitier and Gurtey. 
Plate LX XV. Fig. 5, and Plate LXX VII. Figs. 4a, b, ¢. 
1890. Mutter and Gurizy; Journ. Cincin. Soc. Nat. JERS Oe SUUR. p. 21, Plate 4, Figs. 10 to 12. 
A small and slender species. Calyx fusiform, widest across the middle 
of the radials, whence it tapers both ways; cross section circular; suture 
lines indistinct; surface of plates highly ornamented. The radials are 
covered with five or six longitudinal ridges, which follow the median 
portions of the plates to near the foot of the basals. The ridges do not 
quite reach the top of the radials, and their upper ends are rather obscure ; 
but toward the lower end, and especially upon the basals, they grow quite 
prominent, and terminate in a sort of thickened collar around the column 
facet, giving to the specimens an appearance as if the inner part of the 
base consisted of an independent set of plates. The longitudinal ridges 
are faced laterally by horizontal ones, which traverse the interradial sutures, 
and enter the margin of the adjoining plate. 
Basal cup obconical, rising to two fifths the height of the calyx, the 
upper angles slightly bending inward; radials somewhat projecting next to 
the facet into a lip; facets directed upward, not occupying more than one 
third the width of the plates. Costals short, very closely united. Arms free 
after the first bifurcation ; simple, slender, long, and uniserial throughout; 
joints convex, slightly cuneate, and very short; the two proximal ones 
united by syzygy, with striated, apposed faces (Plate LXXVIL., Fig. 4c). 
Pinnules in close contact, and of moderate length and width. Anal plate 
longer than the radials, and more inflected at the upper end. It supports 
a number of small irregular plates, which form a small protuberance enclos- 
ing the anus; the latter opening out laterally. Ventral disk low-pyramidal : 
( 
