ACTINOCRINIDiE. 555 



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 Steganocriniis 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 tj'pical species Actinocrinus triacontadacti/lus, and there cannot be 

 the least doubt as to which group should retain the name. For the species 

 of section B we propose elsewhere the genus Cactocrinus. 



Actinocrinus urna, and A. Hwiiboldti Troost, are catalogue names. A. viati- 

 cus White, which is probably closely allied to A. tenuiscidj^tiis, is not 

 sufficiently well preserved for description. S. A. Miller's new genus Blairo- 

 crimes is identical with Actinocrinus as now restricted. His Actinocrinus secla- 

 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 Shumakd. 

 Plate LIT. Figs. 3, 4C', I, 5 and 6. 



1857. Shumard ; Trans. Acad. Sei. St. Louis, Vol. I., p. 75, Plate 1, Kg. 5. 



1858. Hall ; Geol. Rep. Iowa, Vol. I., Part H., p. 579, Plate 10, Pig. 9. 

 1881. W. and Sp. ; Revision Pateocr., Part II., p. 144. 



Calyx of medium size, distinctly lobed from a summit or basal aspect. 

 Dorsal cup to the toj) 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 jjlates 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 



