ECHINODERMA TA—CRINOIDEA . 49 5 



l^^\ Arms simple z.^^^. 



2i^^^. Armstwenty or morc.XIX. Woodocrinus. 



^^'^ . Arms usually ten i). 



l). Basals equal a). 



a). IRA and RA present. 



XX. Eupachycrinus. 

 a). IRA and RA absent. 



XXII. Erisocrhius. 

 i). Posterior basal elongate. 



XXI. Ceriocrinus. 



33. Right posterior radial compound XI. Dendrocrinus. 



B. Lower brachials taking part in the calyx II. 



II. All plates of calyx united by close suture. Mouth and food groove closed 



( Camerata') 3. 



3. Lower brachials and interbrachials forming an important part of the dorsal 



cup e. 



e. Interradials poorly defined, with many of them mere irregular supple- 

 mentary pieces LIII. Reteocrinus. 



e. Interradials well defined 44. 



44. Dicyclic cc. 



cc. Radials in contact except at the posterior side It- 



f f . Anal side but slightly elevated. Anus without a tube. 



LIV. Thysanocrinus. 



If. Anal side bulging. Anus at end of a tube ***. 



*^*. Rays produced into tubular extensions, IB large. 



LV. Lanipterocrinus. 

 ***. Rays branching in regular way. IB small. 



LXIII. Siphonocrinus. 



cc. Radials separated all around fff. 



f f f . Arms branching 4* . 



4*. Ventral disk narrower than dorsal cup 4''^. 



4^''. Three interbrachials in second row. 



LVII. Rhodocrmus. 

 i/\ Two interbrachials in second row. 



LVIII, Archceocrinus. 

 4*. Ventral disk equal to or exceeding dorsal cup. Tubular 

 appendages suspended from margin of disk. 



LX. Gilbertsocrinus. 



fif. Arms not branching.. 5*. 



5^. Lower distichals with pinnules incorporated in calyx. 



I^ V I . Hercocrinus. 



5*. Lower distichals without pinnules LIX. Lyriocrinus. 



44. Monocyclic dd. 



dd. Radials in contact all around 4f. 



4f . Arms borne in compartments formed by partitions attached 



to the tegmen 6*. 



6*. Partitions extending to tips of arms. 



LXVII. Eucalyptocrinus. 



6^. Partitions enclosing only the lower portions of the arms. 



LXVIII. Cal/icrinus. 



