50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



2. A ligamentous articulation between the ossicles of the IBr series. 



2. Division series composed of a fixed number of ossicles. 



2. The arms occupy the entire distal border of the radials. 



1. All the arms of equal length. 



1. All the arms terminate in a growing tip. 



1. All the arms are provided with ambulacral grooves. 



Pinnules 



1. Pinnules more or less sharply triangular in cross section. 



1. All of the pinnules similar. 



2. All of the proximal pinnules present. 



1. Side- and covering-plates highly developed. 



1. All of the pinnules provided with ambulacral grooves. 



General 



2. Skeleton composed of less than a million ossicles. 



PHRYNOCRINID^E 



Calyx 



2. Calyx forming a platform upon which the viscera rest, more or 

 less supported by the arm bases. 



1. Calyx reduced by the moving inward of all the calyx plates 



(half). 



2. Calyx reduced by the eversion and imbrication of the calyx 



plates (half). 



1. Basals present. 



1. Five basals. 



1. Basals separate. 



1. Five radials. 



2. Interradials absent. 

 2. Anal x absent. 



2. Interbrachials absent. 



Column 

 1. Entire column present. 



1. Column jointed. 



2. Column not composed of short cylindrical ossicles with radial 



crenellse. 

 2. Column including modified columnals, a proximale or nodals. 



1. Column terminating in an expanded terminal stem plate. 



2. Radicular cirri absent. 

 1. Cirri absent. 



