366 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
A. 
Those in which the ventral disk is highly differentiated, the 
plates being large and heavy, and in which the arms do 
not branch beyond a minute axillary at the arm opening . . . BATOCRINITES. 
B. 
Those in which the ventral disk is composed of small, irregu- 
larly arranged plates, and the arms generally branch after 
Becominetitceue ate eles doe. aon « PERLECHOCRINITES, 
A. BATOCRINITES. 
BATOCRINUS Cassepay. 
1854. Cassepay; Zeitschr. der Deutsch. Geol. Gesellsch., Vol. VI. p. 237. 
1857. Picter; Traité de Paléont., Vol. IV., p. 324. 
1862. Dugsarpin and Hurt; Hist. naturelle des Zoophytes Echinod., p. 142. 
1865. Mernx and Wortusn (Subgenus of Actinocrinus) ; Proceed. Acad. Nat. Sci. Phila., p- 153. 
1866. Mszx and Wortuen (Subgenus of Actinocrinus); Geol. Rep. Ilinois, Vol. II., p. 150. 
1869. Merx and Worruun ; Proceed. Acad. Nat. Sci. Phila., p. 350. 
1873. Mex and Worturn; Geol. Rep. Illinois, Vol. V., p. 364. 
1878. W.and Sp.; Proceed. Acad. Nat. Sci. Phila., p. 329. 
1879. Zitre.; Handb. der Paleontologie, Vol. I., p. 370. 
1881. W. and Sp.; Revision Paleoer., Part II., p. 162 (Proceed. Acad. Nat. Sci. Phila., p. 336). 
1885. Stemmann; Elemente der Paleontologie, Part I., p. 157. 
1890. S.A. Miter; North Amer. Geol. and Paleont., p. 227. 
1892. S.A. Mrtner; Adv. Sheets of the 18th Geol. Rep. Indiana, p. 23. 
Syn. Actinocrinus Gn part) SHumarp, Hatt, Wurre, McCursney, and Merk and WortHEen prior 
to 1865, QuENsTEDT as late as 1885. 
Syn. Uperocrinus (in part) Mrrx and Worruen, 1865; Proceed. Acad. Nat. Sci. Phila., p. 153. 
Calyx biturbinate to subglobose; the rays not lobed. Plates heavy, the 
surface more or less convex and frequently nodose, but otherwise not orna- 
mented. Basals three, proportionally large, forming a hexagonal cup 
thickened at the lower margin, and generally projecting laterally. Radials 
very large. Costals two, small, quite frequently anchylosed ; the first qua- 
drangular, almost linear; the second pentangular. Distichals and palmars 
as large as, or larger than the costals. Palmars are always represented, 
except occasionally in the anterior ray. The posterior rays frequently have 
post-palmars, which do not occur in the other rays. Arm openings equidis- 
tant, directed horizontally. Respiratory pores twenty, two above each 
interradius, and two to each interdistichal space; placed at a somewhat 
higher level than the arm openings. Arms twenty to twenty-six; in species 
with more than twenty arms the extra number is divided between the two 
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