NO. IO PHYLOGENETIC STUDY OF RECENT CRINOIDS — CLARK 47 



PENTACRINITID.E 



Calyx 



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



less supported by the arm bases. 

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



1. Basals present (minority). 



2. Basals absent (majority). 



1. Five basals. 



1. Basals separate (minority). 



2. Basals fused into a single calcareous plate (majority). 



1. Infrabasals present as individual plates (minority). 



2. Infrabasals absent, or fused with other plates (majority). 



1. Five radials (majority). 



2. Ten radials (minority). 



1. Interradials present (minority). 



2. Interradials absent (majority). 



1. Anal x, bearing a process, present (minority). 



2. Anal x, bearing a process, absent (majority). 



1. Interbrachials present (large minority). 



2. Interbrachials absent (small majority). 



Column 



2. Original column discarded in early life. 



2. Column not composed of short cylindrical ossicles with radial 



crenellge. 

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

 (1. Column terminating in an expanded terminal stem plate.) 

 (2. Radicular cirri absent.) 

 2. Cirri present. 



Disk 



1. Disk entirely covered with plates (minority). 



2. Disk naked, or with scattered granules (majority). 



1. Orals present (minority). 



2. Orals absent (majority). 

 2. All five orals of the same size. 



1. Orals with their inner edges upturned (minority). 



2. Orals a spherical triangle (majority). 



1. Mouth central (majority). 



2. Mouth more or less excentric (minority). 



