BATOCRINIDZ. . 405 
half its diameter occupied by the column. Radials large, a little wider than 
long, the upper face concave. First costals narrower and shorter than the 
radials, twice as wide as long, upper and lower faces convex. Second costals 
generally a little longer than the first. Distichals 2 x 2; followed in the 
three anterior rays by two rows of two palmars, which support four arms; 
in the two posterior rays, in one or both divisions, at one side by one palmar 
and two post-palmars, at the other by two palmars, a structure which gives 
to these rays five to six arms, or twenty-two to twenty-four to the species. 
Arms stout, long, incurving, and biserial from the second free plate; they 
gradually increase in width, being at two thirds their length more than twice 
as wide as at the base, and perfectly flat. Also the plates increase upwards 
in length, and their outer faces become transversely angular. Interbrachials 
two; the first very large, the other quite small. Anal plate followed by 
three and two pieces. The upper row at all five sides is arched by the 
palmars and post-palmars. Structure of ventral disk not known. 
Horizon and Locality. — Upper part of Keokuk group; Bono, Lawrence 
Co., Ind. 
Types in the collection of Wachsmuth and Springer. 
Eretmocrinus pregravis S. A. Mixer. 
Plate XXXIV. Figs. 9, 10. 
1892. S. A. Mittzr; Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 37, Plate 6, Figs. 5 and 6. 
A large, very knobby and robust species, in its ornamentation resembling 
Lobocrinus Yandelh ; but the calyx more globular, less distinctly lobed, and 
with a different arm formula. Dorsal cup saucer-shaped, abruptly spreading 
from the base up, the plates heavy and covered with large angular knobs, 
some of which are arranged horizontally, others longitudinally. 
Basals short, forming a hexagon with acute angles; the lower surface 
slightly excavated for the reception of the column, and pierced by a com- 
paratively large axial canal. Radials twice as wide as long, covered with 
prominent transverse nodes, whose tips reach to the level of the lower 
margins of the basals. The node of the intervening anal is round, and the 
plate itself longer than the radials. First costals linear, less nodose than any 
of the other calyx plates, and sometimes completely flat. Second costals 
smaller than the first, depressed pentangular; their nodes subtriangular. 
The posterior and antero-lateral rays have but one distichal in their posterior 
