564 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
off another arm and two post-palmars with two arms. The second arm is 
_ free from the second plate, the two upper ones from above the first. Higher 
brachials separated by deep longitudinal grooves, formed by the lateral in- 
curving of the respective plates; post-palmars very short, resembling free 
arm joints. Structure of the arms unknown. Interbrachial spaces narrow, 
the plates of the regular sides arranged: 1, 2, 3, 3, 3, 3; the anal plate, 
which is smaller than the radials, is followed by 2, 3, 4, and several higher 
rows, of which the exact arrangement cannot be ascertained. Interdistichals 
three or four; rather large. The form of the tegmen is given by Hall as 
“conical, rising gradually from the arm bases to the base of the central 
proboscis.” This appears so in the flattened specimen, but we doubt if its 
natural form was conical. Plates around the summit moderately large and 
tuberculiform, those covering the brachial extensions somewhat smaller, the 
interambulacral pieces still smaller and but slightly convex. 
Horizon and Locality. — Same as last. 
-Lype in the (Worthen) Illinois State collection. 
Actinocrinus multiramosus W. and Sp. (nov. spec.). 
Plate LILI. Fig. 1, and Plate LV. Fig. 8. 
(°) Syn. Aetinocrinus grandis 8. A. Miter, 1890 (not Lyon 1859); Desc. New Genera and Spee. of Echinod., 
p. 25, Plate 5, Fig. 1, and Plate 6, Fig. 1. 
A large species of the type of A. Lowei Hall, with which it closely 
agrees in the mode of ornamentation; differing, however, in the more slender 
form of the calyx, the number of palmars and distichals, in being less dis- 
tinetly lobed, and in having within the calyx three bifurcations in place of 
four. Calyx obconical to the top of the first costals, broadly truncated at 
the base; the distichals and higher orders of brachials given off in clusters, 
bending outward and obliquely upward to the bases of the free arms; the 
interbrachial spaces deeply depressed, and the interspaces between the 
main divisions of the ray deeply grooved. Ventral disk depressed-convex, 
occupying from one fourth to one third the height of the calyx, and sur- 
mounted by a strong tube which rises abruptly from the summit. Plates of 
the dorsal cup heavy and convex, their surfaces covered with sets of well 
defined ridges which traverse the suture lines, and also by large nodes. 
The nodes are placed near the middle of the plates, and those upon the 
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