ORDER II CRINOIDEA—CAMERATA 141 
the lower. Costals one to each ray, very minute, trigonal; they are roofed 
over by the distichals, which rest with their sides upon the &, but are laterally 
in contact with one another. Processes of the tegmen thorn-like and less 
prominent than in Pterotocrinus. Arms two to four. Anus sub-central. Con- 
fined to the St. Louis Limestone of North America. 
Family 3. Actinocrinidae. Roemer. 
Base monocyclic. Basals three, sub-equal ; radials united laterally, except at the 
posterior side, where they are separated by a large anal plate. Fixed brachials large, 
similar in form to the radials. Interradials abundantly represented ; 
the first row interposed between the primary brachials, and consisting 
of a single plate in each of the interrays except the posterior ; the 
second row consisting of two or three plates, and usually succeeded 
by additional rows. Plates of the tegmen numerous, and forming a 
rigid vault. Orals markedly asymmetrical ; anus sub - central, 
eccentric, or marginal, with or without an anal tube. Ordovician 
to Middle Sub-Carboniferous. 
HN) 
kitliyyy 
[The Actinocrinidae, Roemer, according to Wachsmuth and 
Springer, fall naturally into two subdivisions, which are elevated 
by them in their forthcoming Monograph to the rank of inde- 
pendent families. The relations between the two sections, which 
are designated as groups A and 6 in the original, and the genera 
embraced by them, are as follows :— Fia. 242. 
Patelliocrinus lepto- 
A. (AcrrNocrrinipaB, s. str.), [RA hexagonal, succeeded by two ee cana on 
interbrachials without a second anal. (Actinocrinus, Cactocrinus, Natural size (after 
a : ; : s A A ’ Angelin). 
Amphoracrinus, Televocrinus, Steganocrinus, Physetocrinus, Strotocrimus.) ~~ 
B. (Barocrryipak, W. and Sp.), JRA heptagonal, succeeded by two interbrachials 
which enclose a secondary anal. (Batocrinus, Eretmocrinus, Dorycrinus, Agaricocrinus, 
Alloprosalocrinus, Barrandeocrinus, Habrocrinus, Desmidocrinus, Periechocrinus, Megisto- 
crinus, Abacocrinus, ete. | 

(SECTION A.) ACTINOCRINIDAE. 
Actinocrinus, Miller (Fig. 243). Calyx pyriform or ovate; plates of the 
dorsal cup generally ornamented with striae passing from plate to plate. B three, 
equal, forming a hexagon. Three of the # six-sided, generally higher than 
wide ; the posterior pair heptagonal. First costals nearly as high as wide ; 
second costals axillary, supporting both distichals and palmars, and frequently 
higher orders of brachials. J very numerous, passing insensibly into the 
tegmen ; anus sub-central, and borne at the end of a large, strong anal tube. 
Arms biserial ; not bifurcating in their free state, or rarely so; and given off 
in clusters from lateral expansions of the calyx. Pinnules long, slender, and 
laterally in contact. Column long, round ; its joints frequently sharply edged, 
and with striated upper and lower faces. Abundant in Sub-Carboniferous of 
North America and Europe. 
Cactocrinus, W. and Sp. Like the preceding, except that the arms form a 
continuous ring around the calyx, and the /& of the dorsal cup are separated 
from those of the tegmen. Sub-Carboniferous ; North America. 
Amphoracrinus, Austin. Dorsal cup, saucer-shaped or almost flat ; tegmen 
