: 
* \ 
eee & 
HEX ACRINID &. gO) 
Radials once and a half as long as wide, widest across the middle; the upper 
faces deeply excavated to more than one half the width of the plates. Costals 
two, closely anchylosed and very short, their combined length less than their 
width; the lower plate, and partly the upper, resting completely within the 
facet, the distal faces of the upper but slightly angular. Distichals three; 
the two lower plates so closely anchylosed that the suture line is frequently 
obsolete. The costals and distichals, in place of taking the usual outward 
curve, bend slightly inward, so as to make the width of the specimen directly 
above the radials less than the width of the cup. Arms twenty (not twelve, 
as stated by Casseday and Lyon), closely folded at their proximal ends, 
recurving above the second bifurcation, and the tips hanging downward, 
exposing the ambulacra. Pinnules long. Anal plate of the same width as 
the radials, but the lower margin distinctly angular, and the upper concave ; 
it is followed by numerous small plates forming a small, rounded protuber- _ 
ance. Position of the anus almost marginal. Column round. 
Horizon and Locality. — Keokuk limestone; Crawfordsville, Ind., and 
Hardin Co., Ky. 
Types in the collection of the late Major Lyon at Jeffersonville, Ind. 
Remarks. — The specimen which Professor Worthen erroneously figured 
in the Hlinois Geol. Report of 1876 under this name has but ten arms, while 
D. ficus has twenty. Besides, it differs quite essentially in the form of the 
calyx. Curiously enough, Worthen described his specimen as having five 
radials and six costals, evidently supposing, as Casseday and Lyon did, that 
the anal plate supported two arms. 
This species approaches D. pendens in its tendency to pendent arms; but 
the latter is larger, the dorsal cup proportionally wider, the base shorter, and 
bowl-shaped instead of obconical. 
Dichocrinus pentalobus (Cass. and Lyon). 
Plate LX X VILL. Figs. 11a, }, c. 
1860. Cotyledonocrinus pentalobus — CassEDAY and Lyon; Proceed. Amer. Acad. of Arts and Sci., Vol. 
Ves pecos 
1865. (?) Cotyledonocrinus pentalobus —SuuUMARD; Catal. Paleeoz. Foss. N. Amer., p. 360. 
1877. Cotyledonocrinus pentalobus — 8. A. Mitimr; Catal. Amer, Paleoz., Foss., p. 92. 
1881. (?) Cotyledonocrinus pentalobus — Revision Paleocr., Part II., p. 78. 
Calyx elongate; plates thin and without ornamentation. Basals large, 
forming a sub-ovoid cup with a thickened rim around the lower margin; 
bottom but partly occupied by the column. Radials gradually increasing in 
et Sy te A 
ee 
= So ae 
a ay EERIE TIT ENS ES 
ea Ee eae oan 
