HEXACRINIDZ. 769 
Dichocrinus crassitestus Wutte. 
Plate LX XVI. Figs. 6a, b, c. 
1862. Wuuirr; Proceed. Bost. Soc. Nat. Hist., p. 19. 
1881. W.and Sp.; Revision, Paleocr., Part IL., p. 83. 
Of moderate size. Calyx up to the arm bases once and a half as high 
as wide; cylindrical along the radials, obconical below; the posterior side 
extended into a short conical tube, supported by the large anal plate ; 
ventral disk depressed-convex; plates perfectly smooth; the suture lines 
rather obscure. . 
Basal cup fully one third the length of the calyx; conical, the sides 
straight, the lower end sufficiently truncated to form the columnar attach- 
ment. Radials twice as long as wide, the sides parallel or nearly so, the 
lower margins convex (at the anterior plate obtusely angular); the upper 
faces excavated to three fourths their width, slightly sloping at the ends. 
Costals two, linear, their combined length less than their width, and so 
closely anchylosed that the lines of union are seen with difficulty; upper 
face of the second plate very obtusely angular. Distichals 2 X 10, nearly 
one half narrower than the costals, equally short, and anchylosed in a similar 
manner. Arms four to the ray, rather delicate, twice as long as the calyx; 
composed throughout of a single series of short joints, united by parallel 
sutures. Pinnules of moderate size. Anal plate of the same width as the 
radials, but considerably longer ; its lower face distinctly angular, the upper 
truncated, slightly sloping to the sides, and supported by three medium-sized 
plates, which form the base of an anal tube. The tube is rather short, 
conical, placed at the margin of the disk, but bending inward to a position 
between the arms. The plates of the interradial series are not numerous ; 
the three in contact with the radials are followed by two interambulacrals, 
and these by a third. Column small, composed of circular joints, which 
increase in length downward, the nodal joints longest and widest. 
Horizon and Locality. — Upper Burlington limestone; Burlington, Iowa. 
Type in the Museum of Comparative Zodlogy. 
femarks. — This species differs from all others heretofore described in 
the form of the costals and distichals, and in having an anal tube. 
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