7 ow 
HEXACRINID A. 763 
Dichocrinus coxanus WorTHEN. 
Plate LXXVI. Fig. 9. 
1883. WorrHEn; Geol. Rep. Illinois, Vol. VII., p. 313, Plate 27, Figs. 7. 
1885, W. and Sp.; Revision Paleeocr., Part III., p. 120 (Proceed. Acad. Nat. Sci. Phila., p. 342). 
A very small and slender species of the type of D. ornatus. Calyx ovate, 
almost pointed at the lower end, constricted across the costals; greatest dia- 
meter a little above the basi-radial suture. Surface of the plates covered 
with irregular longitudinal ridges, from three to four to each plate, which run 
parallel to the lateral borders of the radials, and are continued along the 
basals to the column. 
Basals as long as the radials; forming a rather high, obconical cup, with 
a very narrow columnar attachment. Radials longer than wide, their lower 
faces moderately convex, the lateral faces nearly parallel, the upper margins 
constricted and to nearly one half their width excavated for the facets. 
Costals two, very short, forming a syzygy. Arms ten, slender, rounded on 
the back; composed of slightly cuneate pieces. Pinnules long. All other 
parts unknown. 
Hlorizon and Locality. — Upper part of Keokuk limestone (Crawfordsville 
division), Hamilton, Ilinois. 
Type in the collection of Mr. L. A. Cox, Keokuk, Iowa. 
fiemarks. — Dichocrinus ornatus, with which this species has the closest 
affinities, has twenty arms instead of ten, the calyx is less contracted at the 
arm bases, broadly truncated at the lower end, and it comes from a different 
horizon. 
Dichocrinus pisum Meek and Wortuen. 
Plate LXXVI. Fig. 5, and Plate LXXVII. Fig. 10. 
1869. Merzx and Worrnen; Proceed. Acad. Nat. Sci. Phila., p- 69. 
1873. Merx and WortHeEn; Geol. Rep. Illinois, Vol. V., p. 441, Plate 3, Figs. 2a, 0, ¢. 
1881. W. and Sp.; Revision Paleocr. Part IL., p. 84 (Proceed. Acad. Nat. Sci. Phila., p. 258). 
Of the type of D. plicatus, but the calyx, instead of globular, subquadran- 
gular in outline, the basal portions more or less flattened, and the sides along 
the radials but very slightly convex. It also resembles D. dneatus in the 
style of ornamentation, but the ridges are coarser and more prominent, and 
the basal cup proportionally smaller and less conical. Height one fourth 
less than the width. Plates thin; the radials covered by from six to eight 
Ke 
