ACTINOCRINID^ (Roemee). 



(Emended and restricted by W. and Sp.). 



Monocyclic. The lower brachials with well defined interbrachials between 



THEM, forming AN IMPORTANT PART OF THE DORSAL CUP. EaDIALS IN CONTACT 

 EXCEPT AT THE POSTERIOR SIDE, WHERE THEY ARE SEPARATED BY A HEXAGONAL 

 ANAL PLATE, WHICH IS FOLLOWED BY TWO INTERBRACHIALS WITHOUT A SECOND 

 ANAL. BaSALS forming A HEXAGON. 



Analysis of the Geneva. 

 Basals 3, equal. Arms biaerial, branching alternately from the main divisions of the rays. 



A. Anus at the end of a tube. 



1. Interbrachials connected with the interamhulacrals. 

 a. Calyx lobed, interradial spaces depressed. 



Anal tube long, central. The branching in the calyx 

 above the distiohals at alternate sides from every 

 second or third plate. Bifurcations of the free arms, 

 if any, at long intervals Aetinocrinus. 



Kays produced into arm-like tubular extensions, rising to 

 the full height of the crown, giving off arms from 

 alternate sides Steganocrinus. 



Anal tube short, exoentric. Ventral disk largely pre- 

 dominating over the dorsal cup. Eays widely sepa- 

 rated. Arms heavy, generally bifurcating in the free 

 state, the branches divergent Amphoracrimis. 



2. Interbrachials not connected with the interamhulacrals. 



a. Calyx not lohed, arms about equidistant, given off in a more 



or less continuous ring around the calyx; anal tube long, 



central. Bifurcations beyond the costals from every brachial 



in the calyx ; arms simple. 



Arms directed upward. Ventral disk conical, gradually 



passing into the tube Cactocrinus. 



Arms very numerous, their lower portions directed out- 

 ward, incorporated into the calyx, and forming a broad, 

 flanging, continuous rim Teleiocrinus. 



B. Anus without a tube. 



a. All bifurcations in the calyx given off from the first brachial 

 of successive orders. 

 Interbrachials connected with the interambulacrals ; in- 

 terspaces between the rays and their subdivisions 

 channeled ; arms arranged in groups ; ventral disk 

 hemispheric, anus excentric Physetoerimus. 



