426 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
and not a distinct species, is clearly shown by the fact that one of our speci- 
mens has but a single paired arm; in another all the arms are paired except 
one, and that we find all variations between these extremes. 
(?) Dizygocrinus Gorbyi S. A. Miter. 
1891. Benne A. Minter; Ad. Sheets 17th Rep. Geol. Surv. Indiana, p. 63, Plate 10, 
ig. 10. 
Of. medium size. Calyx globose, height and width as eight to eleven; 
the arm bases projecting, the ambulacral openings directed upwards. Sur- 
face of plates convex, the radials and brachials transversely angular; the 
suture lines beveled. | 
Basals forming a hexagonal disk, two thirds wider than the diameter 
of the column, the plates upright, exposing a height about equal to the 
distance from the column to the upper margin. Radials very little longer 
than wide, the upper face slightly arcuate. First costals quadrangular, about 
one fourth wider than long; the second wider and longer than the first, 
two of them pentangular, the others hexangular. Distichals 2 X 10, gener- 
ally wider than long, the upper ones larger; nine of them bear a palmar; 
the one of the anterior ray supporting directly an arm. Arms nineteen, 
simple, long, rounded on the back. Pinnules composed of ten to twelve 
long joints. Regular interbrachials three; the first large, nine-sided; the 
two upper smaller. Anal side composed of nine plates; the anal plate the 
largest of the cup; followed by 3, 3, and 2 plates, which decrease in size 
upward. Ventral disk conoidal, covered with convex plates. Anal tube 
almost central, small, cylindrical ; composed of rather large, slightly convex 
plates. Column round, of medium size. 
Horizon and Locality. — Lower part of the Warsaw limestone; Boon- 
ville, Mo. 
Type in the collection of Prof. 8. 8. Gorby at Indianapolis. 
fiemarks. — This species needs to be compared with the type, as Miller’s 
description, from which we give an extract above, does not agree with his 
figure. This is especially the case with regard to the proportions of the 
basals, radials, and costals. The “upright” basals are not seen at all in the 
figure; the radials, and costals, which were said to be but very little wider 
than long, appear extremely short, the distichals are unusually large, and 
are followed by two palmars in the calyx, not by one as described. 
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