500 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
the arm regions and the summit of the posterior oral is pierced by the anal’ 
opening. Orals in contact laterally, large and highly convex; the posterior 
one twice as large as the smaller orals, or larger and equally tumid. 
Horizon and Locality. — Keokuk group; Keokuk, Iowa; Barren and 
Metcalf Cos., Ky.; White’s creek near Nashville, Tenn., and Indian creek, 
Montgomery Co., Ind. 
Types in Professor Wetherby’s collection. 
fiemarks. —'This species is readily recognized by its stellate form, the 
very slight concavity of the dorsal cup, and by the form and arrangement of 
the plates. 
Agaricocrinus elegans WeTHERBY. 
Plate XL. Figs. 3a, 6. 
1881. Wetnersy; Journ. Cincin. Soc. Nat. Hist., Vol. IV., p. 179, Plate-5, Figs. 4, 4a, 0b. 
1885. W.and Sp.; Revision Paleocr., Part IIT.; p. 106. 
Nearest to A. crassus, but smaller and less robust. Calyx depressed, 
pentalobate in a dorsal aspect, with rather. deep recesses between the 
rays; the base moderately excavated. Plates of the dorsal cup slightly 
tumid, basals and radials excepted; the principal plates of the ventral 
disk highly convex. 3 
Basals hidden by the column. MRadials smaller than the costals. First 
costals quadrangular, hexangular or heptangular, as wide as long; the sec- 
ond costals wider than the first, and about as long. First distichals axillary 
in one or both divisions of the posterior rays, supporting 2 X 2 moderately 
large palmars; the other rays have two successive distichals, which interlock 
with those of opposite series, and with the arm plates above. Arm facets 
tending slightly upward, confluent to the second arm plates. Arms three to 
four in the posterior rays, and two in the other rays. First interbrachials 
comparatively short, generally rising to the first costals, sometimes to the 
second. The plates of the second row long, reaching to near a level with 
the arm openings; they support a row of three or four smaller plates, which 
are partly interbrachial, partly interambulacral. Anal area extremely wide ; 
the first plate narrower than the radials, and but very little longer, the three 
succeeding ones almost as large; the latter support three smaller plates, and 
these numerous other plates, which form together a longitudinal, slightly 
elevated ridge, which at half way to the orals is pierced by the anus. Ven- 
tral disk pyramidal. Orals large and highly convex, the posterior one in 
