b 
BATOCRINID &. 413 
Pinnules proportionally large. Interbrachials two to three; the first quite 
large, rising to the top of the first distichals. First anal plate narrower 
than the radials ; followed by two rows of three plates, which are arched by 
the palmars. Ventral disk depressed convex, the interambulacral spaces 
slightly depressed; the orals and radial dome plates considerably larger 
and more convex than the intervening plates. Anal tube composed of 
almost flat pieces ; central, rising considerably beyond the tips of the arms. 
Horizon and Locality.— Lower portion of the Upper Burlington lime- 
stone; Burlington, Iowa. 
Types in the collection of Wachsmuth and Springer. 
DIZYGOCRINUS W. and Sp. (nov. gen). 
(AiZvyos two abreast, xptvov a lily). 
Calyx depressed-subglobose, biturbinate or subconical; the ventral disk 
generally as high as the dorsal cup, and sometimes considerably higher. 
Plates smooth, granular, or obscurely striated. Basals very short, forming 
a slightly projecting circular rim or shallow basin. Radials proportionally 
smaller than in Batocrinus,; the first costals quadrangular, the second pen- 
tangular or rarely heptangular. The upper brachials either form a con- 
tinuous ring around the calyx, or are separated (rarely) between the rays 
by a narrow interbrachial piece; the faces supporting the arms are excavated 
into subcircular or lunate facets, which are directed outward. Arms long 
and biserial, given off from the calyx either singly or in pairs. When the 
arms are paired, they start from a diminutive axillary, and the proximal arm 
plates and this axillary rest upon the same facet; when simple, a large 
cuneate plate takes the place of the three small pieces. Regular interra- 
dials from two to four, at the anal side five to eight. Anal tube almost 
central, slender, and rarely rising above the tips of the arms. Respiratory 
openings small. 
Distribution. — This genus, so far as known, is restricted to the Subcar- 
boniferous of America; it is represented in the Upper Burlington limestone 
by four species, reached its climax in the Keokuk group, and disappeared in 
the Warsaw limestone. 
Type of the genus. — Dizygocrinus indianensis (uyon and Casseday). 
fiemarks. — Most of the species for which we propose this genus were 
described originally by Hall under Actinocrinus, whence they were removed 
by Meek and Worthen, and placed under Batocrinus. Dizygocrinus euconus 
