ORDER III CRINOIDEA—FISTULATA 159 
Arms simple or branching, uniserial, interlocking, or occasionally biserial, and all 
having large pinnules. Devonian and Carboniferous. 
Poteriocrinus, Miller. Dorsal cup obconical; plates thin and plicated around 
their margins so as to form triangular pits at the angles. J/6 equal; B high. 
Three of the & hexagonal; the posterior and the right postero-lateral ones 

] b (35 Tr’ fh) 
GOR | 
Da( >) \\ 
\ brN/f Oe 
Fic. 264. 
Diagrain showing arrangement 
of plates in the dorsal cup of 
Scaphioerinus. 

Fig. 263. FIG. 266. 
Scapliocrinus unieus, Hall. Sub- Diagram of Graphiocrinus. ib, In- 
Carboniferous (Keokuk Group);  frabasals; 6, Basals; r, Radials ; 
Crawfordsville, Indiana. Natural a, Anal; br, Brachials (after 
size. Bather). 

heptagonal, and rising above the level of the others. 
Articular facets crescent-shaped, and rarely occupy- 
ing the full width of the plates. Anal and radianal 
both present. Ventral sac very large, tubular, and 
extending to the full length of the arms; its two 
lowermost plates partially incorporated into the sac. 
Arms long, branching, composed of cuneate joints, 
alternately arranged. Column round or obtusely 
pentagonal. Upper Devonian and Sub-Carbon. 
Lophocrinus, v. Meyer. Devonian ; Nassau. 
Scaphiocrinus, Hall (Hydriocrinus, 'Trautsch.), 
(Figs. 263, 264, 269). Dorsal cup low cup-shaped 
to saucer-shaped. Arrangement of plates and mode of articulation as in the 
preceding ; but the upper faces of the & form a horizontal line, and are 
completely occupied by the lower faces of the first brachials. Costals one 
or two; the axillaries provided with transverse ridge and fossae similar to 
Fic. 265. 
Woodocrinus macrodac- 
tylus, de Kon. Perfect 
specimen from the Car- 
boniferous Limestone 
of Yorkshire (after de 
Koninek). 
