vr 
HEX ACRINIDZ. 801 
Lyori’s. Pterotocrinus rugosus is probably also identical with this species, 
but as the type specimen is fragmentary and badly crushed, no critical com- 
parison is possible, and we think it advisable to accept Wetherby’s name. 
Pterotocrinus acutus, var. bifurcatus (WETHERBY). 
Plate LX XIX. Figs. 9a, b. 
1879. Waetnersy ; Journ. Cincin. Soc. Nat, Hist. (October No.), Plate 11, Figs. la, 4, ¢. 
1881. W. and Sp.; Revision Paleocr., Part IL., p. 91 (Proceed. Acad. Nat. Sci. Phila., p. 265). 
This variety agrees in the general arrangement of its plates with P. acu- 
tus, but differs from it m the form of the dorsal cup and the form of the 
appendages.. The cup is higher and more conical; the basals proportion- 
ally deeper, their lower faces distinctly excavated, and sharply edged around | 
the margin. The appendages are long and extremely heavy throughout; 
they bifurcate widely, in such a way that the divisions from adjoining rays 
meet at their ends and sometimes overlap each other. Column small, filling 
scarcely one half of the basal cavity. 
Horizon and Locality.— Kaskaskia group; Sloans Valley, Pulaski Co., Ky. 
Type in the collection of Prof. A. G. Wetherby. 
Pterotocrinus crassus Mrrex and WorrTHEn. 
Plate LXXIX. Fig. 8. 
1860. Dichocrinus (Pterotocrinus) crassus —Mrnk and Wortuen; Proceed. Acad. Nat. Sci. Phila., p. 382. 
1860. Péerotocrinus crassus — Mexnx and Wortuen; Geol. Rep. Illinois, Vol. II., p. 290, Plate 28, 
Figs. 2a, 6. 
1881. Péerotocrinus crassus — W. and Sp.; Revision Paleocr., Part II., p. 91. 
This species has its closest affinities with P. pyramidalis Lyon and Cass., 
but is somewhat larger, the basal cup deeper, the arms longer and heavier. 
Dorsal cup basin-shaped, more than twice as wide as high, very broad at the 
_base, the sides less spreading than in any of the preceding species, and some- 
what constricted at the basi-radial suture. | 
Basals very large, forming a rounded shallow cup, distinctly concave 
below, and widening gradually from the rounded lower margin to the con- 
stricted upper face. Radials a little convex, broader than long, considerably 
wider above than below; their upper faces slightly concave, supporting the 
costals, distichals, and the outer palmars of the first row. Anal plate sub- 
quadrangular, contracted above, the upper end inflected. Costals very small, 
101 
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