BATOCRINID ZA. 459 
majority of specimens only to the right; while the antero-lateral rays have 
two successive distichals and no palmars. Distichals and palmars are dis- 
tinctly rounded off at the sides, like free arm plates. Arm facets semi-ovate ; 
the ambulacral openings directed slightly upwards, arranged in groups of 
four, two, and three (sometimes four in the anterior ray). The interspaces . 
between the rays are wide, abruptly and deeply depressed, especially at the 
anal side, and those between the various ray divisions are deeply notched. 
Arms in pairs, two from each arm opening, long for the genus, incurving, flat- 
tened at the upper end, and every fourth plate giving off laterally from oppo- 
site sides sharp spines, 2 cm. in length. Interbrachials three, rather large, 
the two of the second row on a level with the arm bases. Anal area very 
wide, forming a low elongate ridge, grooved along the sides, which extends 
up to the posterior oral and contains the anus. First anal plate as long as 
wide, followed by two other anals of smaller size, the two latter sustaining 
an interbrachial at each side. Ventral disk hemispherical, with six long, 
slender, sharply pointed spines. The posterior oral, or plate bearing the 
middle spine, large and central, the other orals rather small and pushed 
anteriorly. The five radial spies are followed by two small secondary 
radial plates, and in rays with four arms by tertiary ones, which enclose 
an interdistichal. Anus opening out laterally, placed at midway between 
the posterior oral and the arm regions. Column very gradually sloping 
downward, with small cirri at the lower end, one to a joint, and at irregular 
intervals. The nodal joints of the upper portion of the stem are longer and 
considerably wider than those of the lower end; they project conspicuously 
over the internodal pieces, but gradually decrease in length and width, and 
at 5 cm. from the calyx have the same form and size as the others. The 
last two internodes in one of the specimens both contain seven joints. 
Horizon and Locality. — Upper and Lower Burlington limestone, Burling- 
ton, Iowa. 
Type in the (Worthen) [llinois State collection, Springfield. 
Remarks. — There can be no doubt that Actinocrinus divaricatus and 
A. decorns, both described by Hall, and afterwards placed by us under 
Dorycrinus, are mere variations of this species, as may be seen by com- 
paring a large number of specimens. The former is a very mature form, 
in which the anterior ray obtained an additional pair of arms; in the latter, 
which came from the Lower Burlington bed, one or both posterior rays have 
but three arm openings, and, as a rule, the spines are shorter. The type 
