BATOCRINIDZ. | 379 
Basal cup trilobate, more than twice as wide as long, flat at the bottom, a 
little contracted at the upper end. Radials more than four times as large as 
the costals, a little wider than long. Costals two, all of nearly equal size, 
but the first quadrangular, the second pentangular; wider than long. Pal- 
mars in two ranges ; the upper supporting the free arms, except those next 
to the anal side, which are axillary and sustain two post-palmars; there 
being five arms to each posterior ray, and twenty-two to the species. The 
anal plate is followed by two rows of three plates each, above which the 
post-palmars meet in lateral contact. At the other interradii the first inter. 
brachials, which are almost as large as the radials, are followed by one or two 
small pieces arched over by the palmars. Arm openings directed horizon- 
tally, arranged at equal distances around the calyx, with a slight depression at 
the posterior side. Arm structure not known. Ventral disk hemispherical, 
a little shorter than the dorsal cup; composed of rather large, tuberculous 
plates of nearly the same size. Anal tube almost central, wide at the base ; 
its length not known. 
Horizon and Locality. —Upper Burlington limestone; Burlington, Iowa. 
(A rare species.) 
Type in the Museum of Comparative Zodlogy. 
Batocrinus tuberculatus W. and Sp. (nov. spec.). 
Plate XX VIII. Figs. 10a, b. 
A very graceful species, rather below medium size. Calyx higher than 
wide, gradually expanding from the basals to the top of the distichals, and 
thence more rapidly to the arm bases. Plates of the dorsal cup tuberculous, 
with well defined sharp nodes in the centre, those of the brachials forming a 
sort of interrupted obscure ridge. 
Basal cup distinctly trilobate, deeply depressed at the interbasal sutures, 
flanging outward at the lower end, and depressed at the bottom. Radials 
about as wide as long, with a large transverse node. Costals small, both 
together very little more than one third the size of the radials; the first 
smaller than the second, quadrangular ; the upper pentangular. Distichals 
two, followed by three palmars, which support the free arms. Arm bases 
directed horizontally, forming an uninterrupted line around the calyx. Arms 
twenty, equidistant, short, rather delicate, flattening at their upper ends, and 
curving inward; their lateral margins indented, and their backs lined by two 
