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406 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
divisions, which is followed by 2X2 palmars and two arms; but in the 
anterior divisions by 2 successive distichals and a single arm. ‘The anterior 
ray, which has but one arm in both divisions, has 2 X'2 distichals. Arm 
facets subcircular, concave, very large, and the surface covered with radiating 
strie. Ambulacral openings quite small. Interbrachials: 1, 2, 1, 2 at the 
regular sides, and 3, 3, 2, 2 on the anal side; the upper row on a level with 
the arm bases. Ventral disk inflated, considerably higher than the dorsal 
cup, the conical upper end passing gradually into the anal tube. The plates 
of the tegmen decrease slightly in size toward the periphery, and are covered 
with sharp nodes as large as those of the dorsal cup. Orals excentric; the 
posterior one quite large. Anal tube stout and composed of large plates 
with sharp elongate nodes; it is almost central at the base, but curves a little 
to one side. Structure of arms and column unknown. 
Horizon and Locality.— Keokuk group; White’s creek Springs, near 
Nashville, Tenn., Pilot Knob, near Louisville, Ky.; Barren Co., Ky., and New 
Ross, Montgomery Co., Ind. 
ALLOPROSALLOCRINUS Cass. and Lyon. 
1860. Casszpay and Lyon; Proceed. Amer. Acad. Arts and Sci., p. 29. 
1866. SHumarp; Catal. Paleeoz. Foss. North Amer., Part L., p. 358. 
1873. Manx and WorrHen (in part); Geol. Rep. Illinois, Vol. V., p. 368 (not M. and W., 1865, Proceed. 
Acad. Nat. Sci. Phila., p. 164). 
1879. Zitren; Handb. der Paleontologie, Vol. L., p. 370. 
1881. W. and Sp.; Revision Paleocr., Part II., p. 118 (Proceed. Acad. Nat. Sci. Phila., p. 287). 
1890. S.A. Minter; North Amer. Geol. and Paleont., p. 229. 
Syn. Conocrinus Troost; List of Crin. of Tenn. (not defined). 
Calyx conical, almost flat below the arm bases. Basals three, equal. 
Costals two, but generally so closely anchylosed that the line of union is 
invisible, and there is virtually but one plate. Distichals one or more, 
either followed by palmars, or directly supporting the arms. The arm-bear- 
ing plates in contact laterally, except upon the anal side, where they are 
separated by the second anal. Arms few to the ray, arranged in groups; 
their facets very large, subcircular and deeply notched at the upper end for 
the reception of the ambulacra. The interbrachials, so far as observed, 
consist of one large plate, except at the anal side, where the first anal is 
followed by a second, which at each side has two short interbrachial pieces. 
Ventral disk conical, its upper end gradually passing into the anal tube, 
which is stout and almost central. The ambulacra subtegminal, their main 
trunks covered by superimposed interambulacral pieces, which are followed 
