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BATOCRINID &. 419 
brachials, which are covered with small tubercles, for distinct plates. Whether 
any multiplication of arms took place in this species is not known. 
Dizygocrinus Whitei W. and Sp. 
Plate XX XTIT. Figs. 10a, b, and Fig. 11. 
1881. Batocrinus Whitei — W. and Sp.; Revision Paleocr., Part IT., p. 169. 
Syn. Batocrinus spergenensis 8. A. MintER, 1891, Adv. Sheets, 17th Rep. Geol. Surv. Indiana, p. 60, 
Plate 10, Figs. 5 and 6. 
Calyx small, depressed globose; the dorsal cup equal to, or but little 
higher than, the ventral disk; the arm regions slightly projecting. Surface 
of plates ornamented. The radials and brachials have along their median 
lines a well defined ridge, and at each side of this ridge, toward the sides of 
the plates, an angular node, which appears in the specimens as if forming an 
independent plate. Ridges or rows of small tubercles occur also on the 
interbrachials, some of them proceeding from the centre of the first plate 
to the radials, others to the higher interbrachials. 
Basals short, forming a projecting circular rim, with a shallow striated 
depression for the reception of the column. MRadials twice as wide as long; 
the sloping upper sides shorter than the corresponding lower ones. Costals 
considerably shorter and narrower than the radials; the first quadrangular, 
the second pentangular. Distichals 2 X 2, of similar form, but smaller than 
the costals; in the anterior ray supporting the arms; in the other rays 
followed by two rows of palmars. The upper faces of all arm-bearing plates 
are directed outward, and formed into circular, rather large facets with 
a notch at the upper end. The surface of these facets is slightly concave, 
and grooved at the inner margin. Arms eighteen, single, infolding, gradu- 
ally tapering, and constructed from the second free plate of two series of 
moderately long pieces. Pinnules very long, composed of joints three times 
longer than wide. Interbrachials: 1, 2, 1, sometimes with an additional 
narrow piece between the arms. Anal plate somewhat higher than the 
radials, and followed variously by 3, 3, and 2 plates or by 8, 2, and 1; the 
latter being generally the case in specimens from the Keokuk group, 
the former in those from the Warsaw limestone. Plates of the ventral disk 
of nearly equal size, all covered with a sharp central tubercle. Anal tube 
long, extended beyond the tips of the arms, constructed of convex plates 
interspersed with slightly nodose or spinous pieces. Column slender; com- 
posed of large and smaller joints, the larger ones with convex edges. 
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