558 THE CEINOIDEA CABIERATA OF NORTH AMERICA. 



convex. Orals separated by perisoinic plates, and larger than the surround- 

 ing pieces ; the posterior one subcentral, wider than high ; the others some- 

 what larger and elongate. Covering pieces of first and second orders 

 irregular, and difficult to distinguish from the superimposed interambulacrals, 

 but those of the higher orders are regularly arranged in two rows. Anal 

 tube nearly central. 



Hoiizon and Localilt/. — Transition bed between the Burlington and Keo- 

 kuk groups. Pleasant Grove, Iowa, Nauvoo, Ills., and Canton, Washington 

 Co., Ind. 



Remarks. — The specimen figured by Worthen as Actinocrimis lohatus 

 Hall, in the Geological Report of Illinois, Vol. VIII., Plate XII., Fig. 8, is 

 a small example of Actinocrinus magnijicus W. and Sp. 



Actinocrinus verrucosus H.iLL. 

 Plaie LII. Figs. 2a, h, c. 



1858. Hall; Geol. Rep. Iowa, Vol. I., Part II., p. 578, Plate 10, Figs. 7a, i. 

 1881. W, aud Sp. ; Revision Pateocr., Part II., p. Ii6. 



Syn. Actinocrinus asterius McChesset ; Descr. New Spec, of Foss., p. 13, aud Trans. Cliicago Acad. 

 Sci.^ Vol. I., p. 9, Plate 5, Fig. 6. 



Approaching in size the two preceding species, but diiFering widely in the 

 proportions of the calyx, the greater convexity of the plates, and their sur- 

 face markings. Calyx distinctly lobed, its height from the base to the foot 

 of the anal tube about equal to the width at the ends of the brachial exten- 

 sions. The'sides o£ the dorsal cup spreading uniformly to the top of the 

 first costals, thence abruptly outward, bringing the plates forming the 

 brachial extensions into a strictly horizontal position. The plates between 

 the lobes are raised slightly above the general surface of the plates be- 

 low, forming a low rim around the upper margins of the dorsal cup, difler- 

 ing in this from the two preceding species, in which this part is impressed, 

 and the brachial appendages are more prominent. Tegmen almost as high 

 as the dorsal cup ; pj^ramidal, rising evenly from the outer margins of the 

 lobes to the summit. Plates of the dorsal cup tumid, and the middle of the 

 radials, first costals, anal plate, and first interbrachials, elevated into a promi- 

 nent node, which, except on the interbrachials, is transversely disposed. 

 From the nodes of the radials and anal plate sometimes two rounded ridges 



