P 
BATOCRINID&. All 
base; the upper palmars abruptly curving upwards, and deeply excavated 
to form the arm facets. Ventral disk near its periphery flat or even concave, 
the plates nearest the margin highly tuberculous, projecting outward and 
upward. Anal tube stout, composed of heavy plates, which are surmounted 
by a short central spine. Interbrachials numerous, consisting of from six to 
eight pieces at the regular sides, and of about eleven to thirteen at the 
posterior one. There are frequently also from one to two interdistichals, 
Column composed of large, rather high joints with distinctly convex edges. 
Horizon and Locality. — Burlington and Keokuk Transition bed, Des 
Moines Co., Iowa, and Nauvoo, Ills. 
Type in the Museum of Comparative Zodlogy. 
Remarks. — This variety forms a transition between Lutrochocrinus Christyi 
and £. planodiscus. 
Eutrochocrinus planodiscus (Hatz). 
Plate XX XIT, Figs. 4a, 6. 
1860. <Actinocrinus planodiscus — Hat; Suppl. Geol. Rep. Lowa, p. 45. 
1873. Batocrinus planodiscus — Munk and WortuEn; Geol. Rep. Illinois, Vol. V., p. 367. 
1878. Batocrinus planodiscus — W. and Sp., Proceed. Acad. Nat. Sci. Phil., pp. 231 and 233. 
1881. Batocrinus planodiscus — W. and Sp.; Revision Paleocr., Part I1., p. 167. 
Of the type of . Christyi, but more closely approaching its variety 
E. trochiscus, with a greater expansion of the calyx than even in that form ; 
conical in the lower portions. From the first costals to the third palmars 
the plates are arranged almost horizontally, the post-palmars decidedly curve 
upwards. Plates slightly convex, their surfaces smooth. 
Basals as in #. Christyt. The radials comparatively smaller than in that 
species; the costals larger, especially the second. Distichals in two ranges, 
as large as, or larger than, the costals. Palmars three, supporting two rows 
of large post-palmars separated by interbrachials, interdistichals, and fre- 
quently by interpalmars. Arm openings forty, eight to each ray; support- 
ing forty apparently delicate arms. According to Hall, the species has 
fifteen interbrachials in nine ranges, nine to eleven interdistichals, and five 
to six interpalmars. A specimen in our collection has only from six to 
seven interdistichals, four interpalmars, and about eighteen plates above the 
anal piece. Ventral disk depressed, deeply concave, except the median 
portions, which support the anal tube and are conical. The radial dome 
plates are more convex and larger than the interambulacral pieces. Posterior 
