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706 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Dichocrinus polydactylus Cassepay and Lyon. 
Plate LXXVILI. Figs. 1a, b. 
1860. Cassrpay and Lyon; Proceed. Amer. Acad. of Arts and Sci., Vol. V., p. 18. 
1881. W. and Sp.; Revision Paleocr., Part IT., p. 84. 
Syn. Dichocrinus expansus Mrex and Wortuen (not De Koninck and Le Hon 1853); Proceed. 
Acad. Nat. Sci. Phila., p. 344; also Geol. Rep. Illinois, Vol. V., p. 500, Plate 14, Fig. 1. 
Of the type of D. lachrymosus. Calyx expanding rather rapidly along the 
basals, thence more abruptly to the top of the radials, where its width is once 
and a half its height. The calyx in a dorsal aspect is sharply hexagonal, 
owing to the convexity of the radials and anal plate, especially in the upper 
parts where the median portions are conspicuously gibbous, producing an 
angular depression along the interradial sutures. The basi-radial and inter- 
basal sutures are also slightly grooved, and the margins of the plates some- 
what beveled. Surface of plates- ornamented with scattered, irregular, 
wart-like nodes, which show a tendency to form vertical rows. Similar 
markings occur upon the radials, where they start from the projecting 
upper rim and run to the lower end of the plates. 
Base large, its height almost one half that of the entire cup; its lower 
face surrounded by conspicuous nodes, which are sometimes confluent and 
form a rim around the lower margin. Radials nearly twice as wide at the 
upper end as at the lower, the upper face almost equal to the length of the 
plates; the facet bounded by a heavy, thickened rim. Anal plate wider and 
longer than the radials, strongly convex in the middle, somewhat inflected 
at the top. Costals two, twice as wide as long. Distichals three; the first 
and second, like the first and second costals generally united by syzygy, 
their suture lines being less distinct than those between the other brachials ; 
the third distichal largest and axillary ; it supports on its outer face a simple 
arm, which slopes obliquely upward, and on the inner face two palmars 
arranged almost in vertical line with the distichals, and resembling them in 
form and size. The second palmar bifurcates again, giving off in the same 
manner as the preceding axillary an arm from the outer side, and from the 
inner two or three post-palmars, which support two simple arms, making 
four arms from each main division, or eight from each ray. Arms biserial 
from the fourth or fifth plate; they are long, rounded on the back, and 
taper very slightly; pinnules closely set and of moderate length. Ventral 
disk higher than the dorsal cup, composed of comparatively large plates ; 
