BATOCRINIDZ&. 395 
at the posterior side, where there are three in the first row, and two or three 
in the second. Ventral disk never as high as the dorsal cup, and in some 
specimens fully one fourth smaller. Posterior oral and radial dome plates 
more prominent and larger than the surrounding plates. Anal tube moder- 
ately large and subcentral. 
Hlorizon and Locality. — Lower Burlington limestone; Burlington, Iowa. 
Types in the Museum of Comparative Zodlogy. 
Eretmocrinus calyculoides (Hatz). 
Plate XXXIV. Figs. 1a, b, 2, 8, 4. 
1860. <Actinocrinus calyculoides — Hatt; Suppl. Geol. Rep. Iowa, p. 17 ; Photogr. Plate 3a, Figs. 2, 3, 4 
(N. York State Bull. No. I.). 
1873. Batocrinus (Eretmocrinus) calyculoides — Mxrnx and WortuEn; Geol. Rep. Illinois, Vol. V., p. 368. 
1881. Hretmocrinus calyculoides —W. and Sp.; Revision Paleocr., Part II., p. 172. 
Calyx below medium size, depressed subpyriform, as wide as high. 
Dorsal cup obconical, truncate at the base, the sides gradually expanding 
from the top of the basals to the height of the first palmars, whence it 
spreads abruptly outward so as to place the arm bases at right angles to 
the diameter of the calyx. Plates flat, the surface devoid of ornamentation, 
and the suture lines obscure. 
Base short, slightly lobed; the lower end somewhat projecting and form- 
ing a sharp edge; the lower face flat, except the median part which 1s mod- 
erately excavated for the reception of the column. Radials almost twice 
as large as both costals together, nearly as long as wide; the upper face 
concave. Distichals 3 X 2 in the anterior ray, and two arms; the other 
rays have 2 X 2 distichals, followed by two palmars and four arms. Palmars 
in contact laterally, very short, and curved like free arm plates, having a 
deep sulcus at each side. Arm facets proportionally large, lunate, directed 
outward, and arranged in groups, there being wider interspaces between the 
rays than between their subdivisions. Arms long, incurving, and biserial 
from their bases up. To the height of about 3 cm. they are subcylindrical, 
when they grow flat and widen gradually, reaching at two thirds their 
height a width of about 6 to 7 mm., which in the upper portions is reduced 
again to 3 mm. The arms in the flattened parts, up to their tips, are 
knife-like, sharp at both sides, and serrated along the edges; the plates are 
short near the calyx, but increase to more than twice their length as the 
arms flatten out. Interradials three, in two rows, except at the posterior 
