POLYZOA. 



65 



by having a notch in the lower margin of the orifice (Fig. 14, Case A 2. 

 Schizoporella unicornis) . 



In many of the Escharina, the front wall of the cell is produced Case B 1. 

 into a stout process or mucro at the lower margin of the orifice (genus 

 Mucronella), or, again, a collar or tube grows up round the primary 



Fig. 14. 



AttVx 



Lp -P^^];. 



Schizopurella unicornis, magnified. 

 Fig. 15. 



Retepora heaniana. 



orifice, thus giving rise to a secondary orifice {Smittia, Porella, etc.. 

 Case B 1). 



In the CelleporidcB (Case B 1) the cells are typically pitcher-shaped Case B i. 

 and arranged vertically, and tend to be heaped up from overcrowding. 



Cellepora pumicosa forms thick pumice-like masses composed of 



F 



