ACTINOCRINID 2. | 559 
tion B is composed of a single plate. In this respect the genus Actinocrinus, 
as now restricted to the species of section A, differs from all the other genera 
of the family, one or two species of Sleganocrinus excepted. 
A consultation of J. S. Miller’s Natural History of the Crinoidea, p. 94, 
shows clearly that his description applies only to section A. He says: 
“When the arms deprived of their fingers project laterally from the sub- 
globose body at the summit of the column, they bear some resemblance to 
the rays or spokes fixed in the nave of a wheel.” This is quite character- 
istic of the typical species Actinocrinus triacontadactylus, and there cannot be 
the least doubt as to which group should retain the name. Tor the species 
of section B we propose elsewhere the genus Cactocrinus. 
Actinocrinus urna, and A, Humboldti Troost, are catalogue names. A, viatt- 
cus White, which is probably closely allied to A. tenwisculpius, is not 
sufficiently well preserved for description. 8S. A. Miller's new genus Blairo- 
crinus is identical with Actinocrinus as now restricted. His Actinocrinus seda- 
liensis is described from a very imperfect specimen, and the casts which he 
refers to that species very probably belong to a different species. 
Actinocrinus multiradiatus Saumarp. 
Plate LIT, Figs. 3, 4a, 6, 5 and 6. 
1857. Suumarp; Trans. Acad. Sci. St. Louis, Vol. I., p. 75, Plate 1, Fig. 5. 
1858. Hat; Geol. Rep. Iowa, Vol. I, Part IL., p. 579, Plate 10, Fig. 9. 
1881. W. and Se.; Revision Paleocr., Part IL, p. 144. 
Calyx of medium size, distinctly lobed from a summit or basal aspect. 
Dorsal cup to the top of the first costals slightly convex, and one fourth to 
one third higher than from there to the base of the anal tube; the second 
costals curving abruptly outward. Distichals and palmars horizontal and 
rounded on the back. They form, together with the plates of the tegmen 
‘overlying them, brachial extensions of the calyx; while the interradial 
plates between them follow the general curvature of the calyx. Plates of 
the cup highly ornamented with strong, somewhat undulating ridges, which 
in sets of from one to four run from near the middle of the plates to the 
outer margins, where, crossing the sutures, they unite with those from 
adjoining pieces, and form a number of sets of from two to three concentric 
triangles. The radials generally have above the centre of the plates a trans- 
verse node, from which four prominent ridges proceed to the basals; three 
