430 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
erably higher than the radials, and supports 3, 2, and 1 plate, the latter 
resting between the arm-bearing palmars. Plates of the tegmen nodose and 
of uniform size; the anal tube rather stout, and composed of slightly convex 
pieces, which at intervals are interspersed with tuberculous pieces. Column 
decreasing in size downward, the joints long. 
Horizon and Locality. — Keokuk group; Indian creek, Montgomery Co., 
Ind. 
Types in the collection of Wachsmuth and Springer. 
ftemarks. —This species resembles Dizygocrinus biturbinatus Hall, from 
which it differs in the arm formula. Specimens in which the arms all are 
single have not as yet been discovered. 
Dizygocrinus euconus (Mzrex and Worruey). 
Plate XXXV. Figs. 7a, b. 
1865. <Actinocrinus (Alloprosallocrinus) euconus —M. and W.; Proceed. Acad. Nat. Sci. Phila., p- 164. 
1875. Batocrinus (Alloprosallocrinus) euconus —M. and W.; Geol. Rep. Illinois, Vol. V., p- 368. 
1881. Batocrinus euconus —W. and Sr.; Revision Paleocr., Part IT., p. 166. 
Syn. Batocrinus subconicus —WortHEN ; Geol. Rep. Illinois, Vol. VIIL., p. 84, Plate 13, Figs. 4 and 4a. 
In general form resembling Adloprosallocrinus. Dorsal cup very slightly 
convex, the sides spreading abruptly from the top of the basals to the arms. 
Base small, projecting, circular in outline, with a shallow depression for the 
reception of the column. Surface of plates smooth, without ridges or other 
elevations. Suture lines indistinct. Radials hexagonal, about twice as wide 
as high. First costals quadrangular, smaller than the second. Distichals 
two, followed in the two antero-lateral rays by two rows of two palmars, and 
four single arms; while the anterior ray, which has an additional distichal at 
each side, and no palmars, has two arms. The posterior rays have palmars 
in the division next to the anal side and three arms, there being sixteen arms 
to the species. Structure of the arms unknown. Interbrachials three at the 
regular sides, and six above the anal plate, the upper row at all sides arched 
by the arm-bearing brachials. Ventral disk regularly conical, twice as high 
as the dorsal cup, composed of rather large, slightly convex pieces; the pos- 
terior oral erect, and forming the base of the anal tube. The tube stout at 
the base and nearly central. 
Horizon and Locality. — Warsaw limestone ; Spergen Hill, Ind., Union Co. ; 
Ills., and Taylor Co., Ky. 
Lype in the Illinois State collection, Springfield. 
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