122 SMITHSONIAN INSTITUTION 



Suborder SAGENOCRINOIDEA 



Family LECANOCRTNIDAE Springer 



SAGENOCRINOIDEA WITH INFRABASALS MORE OR LESS ERECT, FORMING AN ESSENTIAL PART OF 

 THE CALYX WALL. CROWN USUALLY SHORT, ROTUND. 



Analysis of the Genera 



I. Rays in contact except at anal side. 

 Arms dichotomous. 



RA rhombic, obliquely to lower left of r. post. R. 

 Anal x alone. 



Arms interlocking. IBr 2 (exceptionally i) Lecanocrinus. 



NoRA. 



Anal x alone, or followed by small triangular plate. 



Arms not interlocking, usually rounded, with dextrorse twist. 



IBr 2 Mespilocrinus. 



II. Rays above radials partly separated by solid plates arched over by 

 brachials. 

 Arms heterotomous. IBr 2. 



Base highly specialized. IBB enveloping BB. 



Anal x and large iBr followed by others. 

 RA under r. post. R, between BB. 



io main rami, with ramules Homalocrinus. 



NoRA. 



20 main rami, with ramules Calpiocrinus. 



Arms usually dichotomous. IBB of usual form. IBr 2. 



RA irregularly under r. post. R, above line of BB (exceptionally 

 oblique, or wanting) . 

 Anal x and iBr i large alone, or followed by others Anisocrinus. 



III. Rays above radials separated by solid plates followed by perisome. 



Arms dichotomous. No RA. IBr 2. 



Anal x and large iBr followed by others abreast and perisome, 



or directly by perisome Hormocrinus. 



IV. Rays above radials separated by perisome only. 



Arms heterotomous. IBr 2. 



RA rhombic, obliquely to lower left of r. post. R. 

 Anal x followed by perisome. No iBr. 



io main rami with irregularly branching ramules Cholocrinus. 



Arms dichotomous. 



RA rhombic, obliquely to lower left of r. post. R. 

 Anal x followed by others passing into a tube. 



No iBr, areas filled with perisome, sometimes not exposed. 



IBr 2 Asaphocrinus. 



Anal x alone, followed by perisome. 



No iBr, areas wide filled with perisome. IBr I to 4 Pycnosaccus. 



No RA, anal plate, or iBr. 



iBr areas wide, filled with perisome. IBr 2 to 4 Nipterocrinus. 



