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806 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
rally occupies a radial position; but it does not agree with A, Shumardi. Tn 
this species there are only two plates in radial succession; the plate which 
we described as the “second” radial rests upon two contiguous plates, which 
are both interradial. 
The accessory pieces were multiplied by the addition of new rings above 
the basals. This is well shown by the small specimen of A. Wortheni, and 
by some of the smaller specimens of A. amphora, in which the plates of the 
last ring are yet trigonal, while in the larger specimens, with additional 
rings, they are heptagonal. 
Acrocrinus Shumardi Yanpe tt. 
JECTS OP. OO a RNa Why aro 
1847. Yanpext and Saumarp; Contributions Geology Kentucky, Plate 1, Fig. 3 (figured without descrip- 
tion or name). 
1855. Yanprnt; Amer. Journ. Sci. and Arts, Vol. XX. (new ser.), p. 185 (with figure). 
1885. W. and Sp.; Revision Paleocr., Part III., p. 122. 
Syn. Acrocrinus urneformis — Hat; 1858, Geol. Rep. Iowa, Vol. I., Part II., p. 690, Plate 25, 
Figs. 9a, 6. 
A large species. Calyx urn-shaped, apparently more than twice as long 
as wide; the plates thin, almost flat, and without ornamentation. 
Basals forming a large basin; the lower face rather broadly truncated, 
and extended outward into a small rim; the interbasal suture slightly 
grooved. ‘The plates separating the basals from the radials arranged in 
fourteen to twenty rings, more or less, each ring containing from twenty-five 
to thirty plates, except the upper one which has but eighteen. They are 
arranged in a similar manner as in A, Wortheni, gradually increasing in size 
upward, and the lower ones longer than wide, the upper as wide as long. 
Radials irregularly heptagonal, larger than any of the preceding plates, short 
but extremely wide, their width being three to four times their height; the 
upper face of the radials is excavated to fully three fourths its width, form- 
ing a deep, rounded facet, which encloses the costals and both distichals. 
Anal plate a little longer than the radials, and like these supported by four 
plates. Costals one, minute, trigonal, occupying about one tenth the width 
of the facet. Distichals and palmars two, transversely linear; the latter but 
half the width of the distichals. Arms apparently eight to the ray, erect and 
biserial. The structure of the disk has not been observed, but it was doubt- 
less flat, and the anal opening, as shown by the specimens, frequently was 
covered by a Gasteropod. Column of moderate size, composed of rather 
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