52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



Column 

 I. Entire column present. 



1. Column jointed. 



2. Column not. composed of short cylindrical ossicles with radial 



crenellae. 

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

 2. Column without a terminal stem plate. 

 1. Radicular cirri present. 



1. Cirri absent. 



Disk 



2. Disk naked. 

 2. Orals absent. 



1. Mouth central. 



A rms 



2. Arms with IBr series. 



1. Arms with IBr series in which the outer element is axillary. 



2. The first bifurcation is on the second post-radial ossicle. 



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 are of equal length. 



1. All the arms terminate in a growing tip. 



Pinnules 



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



1. All of the pinnules similar. 



1. Pinnulation of the arm bases more or less deficient. 



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. 



holopoduxe . 

 Calyx 



1. Calyx in the form of a cup, protecting the viscera dorsally and 



laterally. 



2. No basals. 



2. No infrabasals. 



