

ORDER ii VCRINOIDEA CAMERATA 1 4 1 



the lower. Costals one to each ray, very minute, trigonal ; they are roofed 

 over by the distichals, which rest with their sides upon the R, but are laterally 

 in contact with one another. Processes of the tegmen thorn-like and less 

 prominent than in I'terotocrinus. 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, 

 xiiiiilnr in for/n fo the radials. Interradials abundantly represented ; 

 the first row interposed between the primary brachials, and consisting 

 < if 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. 



[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 B in the original, and the genera 

 embraced by them, are as follows : Fl - 242 - 



Patelliocrinus lepio- 



A. (ACTINOCRINIDAE, s. str.), IRA hexagonal, succeeded by two gSSrian; ^Sfttiand'. 

 interbrachials without a second anal. (Actinocrinus, Cactocrinus, ^Jjjj* size (after 

 Amphoracrinus, Teleiocrinus, Steganocrinus, Physetocrinus, Strotocrinus.} 



B. (BATOCRINIDAE, W. and Sp.), IRA heptagonal, succeeded by two interbrachials 

 which enclose a secondary anal. (Batocrinus, Eretmocrinus, Dorycrinus, Agaricocrinus, 

 Alloprosalocrinus, Barrandeocrinus, Habrocrinus, Desmidocrinus, Periechocrinus, Megisto- 

 crinus, Abacocrinus, etc.] 



(SECTION A.) ACTINOCRINIDAE. 



Actinowinus, 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 R 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. IR 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 IR 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 



