BATOCRINID&. 493 
and the more extravagant form of the anal protuberance. A. Wortheni is a 
much larger species, and its anal area throughout is perfectly flat. 
Agaricocrinus nodosus Merk and WortHen. 
Plate XLLIIT. Fig. 9. 
1869. Merk and Wortuen; Proceed. Acad. Nat. Sci. Phila., p. 167. 
1873. Msn and Wortuen; Geol. Rep. Illinois, Vol. V., p. 897, Plate 10, Figs. Ya, 0. 
Closely resembling A. excavatus, and perhaps a mere variety of that 
species. It agrees with it in the general form of the calyx, the convexity 
of the dorsal cup, and the form and arrangement of the basals and radials; 
the first costals, however, are somewhat shorter, and always quadrangular 
owing to the greater length of the first interbrachials; while the second cos- 
tals for the same reason are generally octagonal. The latter plates, like the 
first interbrachials, are larger, and their upper portions, which do not take 
part in the basal concavity, are strongly convex or even nodose. Also the 
first distichals, which next to the axillary costals constitute the largest plates 
of the calyx, are decidedly convex, and so to some extent are the inter- 
brachials of the second row, which are narrow and rise to a level with the 
arm bases. Second distichals small and cuneate, not extending out to the 
full width of the first, the outer ends being occupied by the succeeding arm 
plate, which meets it from the opposide side. The posterior rays have 
toward the anal side but one distichal, which is axillary, and supports 
from each side a palmar. Arms twelve, not quite as stout as in A. exca- 
vatus, and the anal process less protuberant. 
Forizon and Locality.— Upper part of the Upper Burlington limestone, 
Pleasant Grove, Des Moines Co., Iowa. 
Type in the Museum of Comparative Zodlogy. 
Remarks. — This and the preceding species were placed by us in Part II. 
of the Revision (p. 112) with Agaricocrinus americanus. with which they both 
have close affinities. 
Agaricocrinus bullatus Hatt. 
Plate XII. Figs. 2a, b, ¢, d. 
1858. Hatt; Geol. Rep. Iowa, Vol. I., Part IL, p. 562, Plate 9, Figs. 11a, 4. 
Syn. Agaricocrinus pentagonus —Hat1, 1860; Suppl. Geol. Rep. Iowa, p. 57; and Whitfield, 
Amer. Mus. Nat. Hist. N. York, 1893, Vol. I., p. 25, Plate 2, Figs. 17, 18. 
Of medium size. Calyx depressed pyramidal, distinctly pentangular 
below the arm bases, and rather deeply concave at the bottom. The con- 
