590 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Horizon and Locality.— Lower Burlington limestone ; Burlington, Iowa, 
and Lake Valley, New Mexico. 
Type in the (Worthen) Illinois State collection, Springfield. 
ftemarks. — With the excellent material before us, we have attempted in 
vain to separate from this species Actinocrinus planobasilis Hall, Actinocrinus 
quadrispimus White, and Amphoracrinus divergens, var. nultiramosus M. and W. 
We admit that in some of the specimens the radials and costals are com- 
paratively shorter, the number and branching of the arms slightly different, 
and the surface ornamentation somewhat coarser or almost obsolete ae UNG 
these characters appear to be independent of each other. Nor can the fork- 
ing of the oral spines, upon which Meek and Worthen proposed a variety, be 
considered a valid distinction, because it occurs as well in the smaller speci- 
mens of the type of A. guadrispinus, as in the typical form of Amphoracrinus 
dwergens. | 
Amphoracrinus viminalis (Hatz). 
Plate LIV. Fig. 8. 
1863. <Actinocrinus viminalis — Hawn; 17th Rep. N. Y. State Cab. Nat. Hist., p. 54, and. 1875, Geol. Surv. 
Ohio, Paleont., Vol. IT., p. 165, Plate IT., Figs. 12 to 14. 
1881. <Amphoracrinus viminalis— W. and Spr.; Revision Paleocr., Part II., p. 155. 
Below medium size. In the form of the dorsal cup, style of ornamenta- 
tion, as well as the general structure and mode of branching of the arms, 
resembling the preceding species. Dorsal cup depressed turbinate, the sides 
rapidly and uniformly spreading from the truncated base to the top of the 
costals, above which the brachials form free lobes, which droop to about the 
first bifurcation of the arms, leaving only the basals and radials visible from 
a side view. Plates almost flat, except for the general curvature, but owing 
to the rather deep grooves at the sutures they have the appearance of being 
slightly convex; their surface obscurely granulated. 
- Basals forming a very short, subhexangular cup, which slightly projects 
over the sides of the column; the interbasal sutures distinct but not grooved. 
Radials two thirds as long as wide, and as large as, or larger than, both cos- 
tals together; the lower sloping sides much longer than the corresponding 
upper ones. First costals quadrangular, three times as wide as long; the 
second smaller than the first, broadly triangular in outline; they are followed 
by 2X2 short, quadrangular distichals, which are connected laterally by 
