ACTINOCRINID&. 561 ‘| 
Actinocrinus pernodosus HAL. 
Plate LV. Figs. 2a, 0. 
1858. Haz; Geol. Rep. Iowa, Vol. I., Part II., p. 608, Plate 15, Figs. 3a, 6, and Plate 16, Fig. 7. 
1881. W. and Sp.; Revision Palxocr., Part IT., p. 145. 
Nearest to A. verrucosus, but of larger size, the plates heavier and de- 
cidedly more nodose. Calyx a little higher than wide, uniformly spreading 
from the broadly truncated base to the top of the second costals, whence the 
rays spread obliquely outward. The interbrachial spaces curve slightly 
inward, and form deeply depressed areas, which give to the calyx from a 
ventral aspect a strongly pentalobate outline. Tegmen short, depressed 
convex. Plates of the dorsal cup massive and highly elevated, the surfaces 
rising obliquely from the suture lines to near the centre of the plates, and 
thence abruptly to their summits, there forming conspicuous nodes, which 
upon the radials and brachials are transversely arranged. From these 
nodes, broad ridges proceed to adjoining plates, two — exceptionally three — 
from the radials to the basals, while there is but one between the other 
plates. These ridges and nodes give to the surface a rugose and rough 
appearance. 
Basals large, projecting outward, and forming with their lower margins a 
strong rim around the top of the column, which is deeply notched between 
the plates. Radials as long as wide, or longer; their sloping upper faces 
much shorter than the lateral ones. First costals less than half the size of 
the radials, nearly as long as wide; the second as wide as the first, but only 
half as long. Distichals small, giving off an arm to one side, and two pal- 
mars to the other; the latter supporting on their axillary two arms, which 
are free from the second plate. Distichals and palmars quite short, angular 
on the back, and separated from adjoining brachials of the same ray by deep 
grooves, formed by the incurving sides of the plates. Arms six to the ray, 
stout, long, and apparently simple throughout. Regular interbrachials: 1, 
2, 3, followed by a number of smaller plates, which gradually pass into 
interambulacrals, and decrease in size upwards. The anal plate, which is 
smaller than the radials, is followed by 2, 3, and 5 pieces. There are no 
interdistichals between the main divisions of the rays. Orals and all ambu- 
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