BATOCRINIDZ. , 443 
convex ; in some species quite prominent and the surface slightly rugose, in 
others almost flat and perfectly smooth. Suture lines grooved. 
Base short, hexagonal in outline, rounded at the bottom, the column facet 
slightly excavated, the interbasal sutures impressed. Radials wider above 
than below, deeply notched for the reception of the first interbrachial, the 
upper face concave. Costals rather large for the genus, together about equal 
to the size of the radials; the upper larger and generally heptagonal. Dis- 
tichals two, smaller than the costals, the axillaries supporting 2 X 2 palmars, 
and normally four arms to the ray; frequently, however, the anterior ray 
has but two or three arms, and an additional fixed distichal in place of pal- 
mars. Arm openings directed obliquely upwards; the interspaces separating 
the rays a little wider and deeper than those between the openings of the 
same ray. Arms from eighteen to twenty, long, rounded on the back, grad- 
ually tapering but not infolding, and composed from the calyx up of two 
rows of transverse pieces. Pinnules long and cylindrical. Interbrachials 
from five to seven; the lower wider than long, and generally not rising 
to the full height of the second costals. There are two comparatively large 
plates in the second row, and one in the third, followed by one or two 
irregular pieces, which separate the rays at the arm bases. Anal plate con- 
siderably longer than the radials, supporting three plates in the first, and 
three to four in the second range; the succeeding ones irregularly arranged 
and interlocking with the mterambulacral plates. Ventral disk depressed 
conical. Orals and radial dome plates a little larger than the interambulacral 
pieces; arranged in the usual way. Anal tube stout and very long, rising 
in some specimens as much as 6 cm. beyond the tips of the arms; the plates 
smooth. Column round, of medium size, the nodal joints rounded at the 
edges, the others considerably narrower near the calyx, but attaining the 
same width farther down. 
Horizon and Locality. — Lower Burlington limestone; Burlington, Iowa, 
and at several places in Missouri. 
Type in the (Worthen) Illinois State collection, Springfield. 
Remarks.-— We regard Batocrinus cassedayanus M. and W., as a mere | 
variation of this species; the plates, although more convex than in the typi- 
cal form, are arranged in exactly the same way. 
