574 THE CEINOIDEA CAMERATA OF NORTH AlVEEEICA. 



length provided with short hooks. Eegular interbrachials : 1, 2, 3 ; the 

 first almost as large as the radials ; the plates of the upper row interlock- 

 ing with those from the tegmen. The anal piece is followed by 2, 3, and 

 4 plates. Interdistichals one. Tegmen short, the interambulacral plates 

 and orals flat, all of nearly the same size ; the ambulacral pieces the smaller, 

 a little convex and formed into ridges. Anal tube of medium size, the plates 

 covered with a minute central tubercle. Column moderately large, the nodal 

 joints widest, their edges convex, and bordered by small nodes. 



Horizon and Locality. — Upper Burlington limestone; Burlington and 

 Pleasant Grove, Iowa. 



Types in the collection of Wachsmuth and Springer. 



Remarks. — This species differs from A. temiisculptiis, with which it has 

 its closest affinities, in the mode of ornamentation of the dorsal cup, the 

 wider interspaces between the rays at the arm regions, and in having flat 

 instead of spiniferous plates in the tegmen. It also occurs at a different 

 geological horizon. 



Actinocrinus daphne Hall. 

 riate LVI. Ficj.l. 



1864. Hall ; 17tli Rep. N. Y. State Cab. Nat. Hist., p. 52. 



1875. Hall ; Geol. Surv. Ohio, Palsont., Vol. II., Pavt H., p. 162, Plate 11, Fig. 11. 



1881. W. and Sp. ; Revision Palseocr., Part II., p. 143. 



Calyx of medium size, its exact form indeterminable owing to the crushed 

 condition of the specimens ; the base truncated only to the width of the 

 column ; the rays but slightly lobed ; the arms given off in clusters as in 

 A. tenuisculjHus, with moderately wide interspaces between the rays. Plates 

 rather delicate ; their surface marked by radiating ridges running from the 

 centre of the plates to their margins, where they meet those of adjoining 

 plates. The ridges passing up the radials and brachials, and down to the 

 basals, somewhat more prominent. 



Basals rather large, forming a spreading cup with a slightly projecting, 

 nan-ow rim around the lower margin, which is readily taken for the upper 

 stem joint ; interbasal sutures indistinct. Eadials longer than wide ; the 

 costals wider than long ; the first hexagonal, smaller than the second, and 

 less than two thirds the size of the radials. Distichals smaller than the first 

 costals, supporting at one side an arm, at the other two palmars with two 



