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GENUS IV. HORMATHIA (Gosse). 
Base adherent; greatly expanded. 
Column pillar-like, much corrugated, surrounded 
by a single horizontal row of warts. 
Disk slightly concave ; scarcely exceeding the 
column. 
Tentacles moderately long and slender; perfectly 
retractile. 
There is but a single known species, H. Mar^arilcs. 
