RHODOCRINIDAL RoOEMER (1855). 
Dicycuic. LOWER BRACHIALS AND INTERBRACHIALS FORMING AN IMPORTANT PART OF 
THE DORSAL CUP. RADIALS SEPARATED ALL AROUND BY AN INTERRADIAL PLATE 
WHICH IS FOLLOWED BY WELL-DEFINED, REGULARLY ARRANGED INTERBRACHIALS. 
Analysis of the Genera. 
Infrabasals 5. Basals 5. 
A. ANAL INTERRADIUS GENERALLY WITH ADDITIONAL PLATES. 
1. Arms uniserial. 
a. Arms not branching. 
Basals exposed ina side view . . . . . . . . + RHAPHANOCRINUS- 
2. Arms biserial. 
a. Arms branching. 
Calyx obovate; anus without a tube; interbrachials 
numerous, two in second row; interdistichals gen- 
erally present . . . . . + + + + + +. + ARCHEOCRINUS. 
Calyx depressed globular, anus at end of a tube, first 
interradials frequently separated from basals by 
supplementary pieces. No interdistichals. Arms 
probably given off from brachial prolongations of 
thecalyx .... ++ +. + + + + « « DIABOLOCRINUS. 
Calyx globose, flattened or concave below ; two or three 
interbrachials in second and succeeding rows; no 
interdistichals. 
Ventral disk narrower than dorsaleup. . . RuopoOCRINUS. 
Ventral disk equal to, or exceeding dorsal cup; 
tubular appendages suspended from mar- 
ginofdisk . .-.... + -. . . GILBERTSOCRINUS. 
b. Arms not branching. 
Calyx globose, arms long and heavy ; interdistichals 
TENN OG 6 9 6 0 6 o-n 8 mo a oO oy aMzqadNofoyoprbuspory 
B. ANAL INTERRADIUS WITHOUT ADDITIONAL PLATES. 
1. Arms biserial. 
a. Arms not branching, dorsal cup broadly truncate at the bot- 
tom, radials sometimes not all separated; arm facets 
directeditupward si. iene. 7 el ee «eo LynrI0cRINvs. 
b. Arms branching. 
One costal; interdistichals few. . . . . + + = + ANTHEMOCRINUS. 
Two costals; rays produced into long trunks giving off 
armlets from opposite sides . - - + + «+ + « RIPIpOCRINUS. 
C. ANAL INTERRADIUS UNKNOWN. 
Arms uniserial, branching frequently ; infrabasals very small . DrAmENocrINUS. 
