HEXACRINID&. gags 
Dichocrinus dichotomus Hatt. 
1859. Hatz; Suppl. Geol. Rep. Iowa, p. 85 (diagram Plate 1, Fig. 5). 
> 1881. W. and Sv.; Revision, Paleocr., Part IL., p. 88. 
According to Hall, the calyx is shallow cup-form, the basals occupying 
one third its height. Radials wider than long, the lower margin of the facet 
slightly thickened. Costals extremely short and narrow, occupying scarcely 
the fifth part of the width of the radials at the top. Arms dichotomizing 
twice or oftener, uniserial in the lower portions; composed of cuneate plates, 
which gradually interlock upward. Surface of plates “punctate or marked 
by slight rounded depressions, separated by narrow, elevated lines.” 
Horizon and Locality. — Warsaw limestone, Warsaw, III. 
Remarks. — This species was described from a crushed specimen in the 
collection of the late Professor Worthen, from which the characters cannot i 
be satisfactorily ascertained. I 
Dichocrinus Humburgi 8. A. Mitzer. | 
1891. 8S. A. Mitter; Geol. Surv. Missouri, Bull. 4, p. 26, Plate 3, Figs. 9 and 10, and Adv. Sheets 
17th Rep. Geol. Surv. Indiana, p. 36, Plate 6, Fig. 38. | 
Described from two specimens, which are only preserved to the second 
palmars, and, according to Miller, “show considerable variation in size and 
relative proportions,” the radials of the one “only about one half longer 
y) 
than wide,’ in the other “twice as long as wide.’ Basal cup a little less iH 
than half the length of the calyx, obconical, truncated, and shghtly concave 
_— 
at the bottom, the column not filling the lower concavity, the re-entering | 
angles “hardly discernible on either side.” Radials expanding but little, | 
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the facets occupying nearly the entire width of the plates. Costals “ one,” 
thin and axillary. Distichals two. Arms twenty, uniserial so far as observed. 
Anal plate a very little smaller than the radials, the upper end contracting. 
Surface of plates smooth. 
Horizon and Locality. — Lower part of Warsaw limestone; Boonville, Mo. | 
Type in the collection of Mr. R. A. Blair, of Sedalia, Mo. I 
Remarks: — The two specimens alluded to above not only differ in the 
proportions of the plates, but also the re-entering angles meeting the basi- 
radial suture, which in the one were said to be “hardly discernible,” are in Ne 
the other, according to figure, unusually deep. The specimens evidently at 
98 
