BATOCRINID &. O37 
Megistocrinus nobilis W. and Sp. 
Plate XLVI. Figs. 6, 7, Sa, 6, and Plate LI. Fig. &. 
1890. W. and Sp.; Geol. Rep. Illinois, Vol. VIII., p. 169, Plate 16, Figs. 6 and 7. 
1890. §. A. Minter; North Amer. Geol. and Paleont., p. 260. 
Syn. Megistocrinus parvus W. and Sp.; Geol. Rep. Llinois, Vol. VIII., p. 171. 
Somewhat smaller than the preceding species. Calyx subglobose, nearly 
as wide as high; the tegmen depressed hemispherical. Dorsal cup to the 
middle of the radials slightly flattened, but still convex; the costals and 
proximal distichals gently curving; the higher brachials bending outward 
and curved transversely, forming ten lobes around the calyx, correspond- 
ing to the main divisions of the rays. Plates heavy, a little concave ; suture 
lines somewhat grooved, those between the basals and radials deeper than 
the others. 
Basals small, forming a hexagon, of which only a narrow rim is visible 
beyond the column. Radials hexangular in outline, a little wider than long, 
the upper and lower lateral faces of equal length. First costals as large as 
the radials; the two posterior ones pentangular, the others hexangular. 
Second costals smaller than the first, and pentangular. First distichals as 
large as the axillary costal; those of the second row somewhat smaller; suc- 
ceeding distichals biserial, the plates alternating, and decreasing rapidly in 
length upward. There are four platesin one series and five in the other, 
both followed by two series of short transverse palmars, which to the third 
plate take part in the calyx, and bifurcate again above the fifth or sixth. 
Arm facets arranged in ten pairs, large, and directed upwards. Arms short 
in proportion to the size of the calyx, bifurcating three or four times, the 
tips infolding ; they are robust at their bases, but diminish in size with each 
bifurcation, and are composed of moderately short pieces. Pinnules short 
and rarely preserved. Regular interbrachials in five or six ranges: 1, 2, 2, 
3, 3, 2, with slight variations. Interdistichals in three or four rows; the 
first generally resting upon the second distichals, rarely upon the first. The 
first anal plate longer than the radials; the three plates above as large as 
the first interbrachial of the other sides; followed by four or five plates, and 
these by numerous others of indefinite arrangement. Ventral disk from 
almost flat to moderately convex; the plates flat, of almost uniform size 
and irregular arrangement. The orals, if represented at all, indeterminable, 
68 
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SSS Ee 
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