Ethology = 0819: — 
Habits, behaviour 
Plankton 
Symbiosis 
Variation and Aetiology = 0823 : 
Variation. . 
Phylogeny 
Distribution = 0827 
Recent : — 
Atlantic and adjacent seas 
Indian and adjacent seas 
Pacific and adjacent seas 
Arctic and Antarctic . . 
Freshwater . . 
Geological : — 
Secondary 
Primary 
III. Systematic = 0831 : — 
Hydrozoa( = Hydromedusae) 
Graptolithida 
Scyphozoa Scyphomedusae) . 
Anthozoa 
Alcyonaria 
Zoantharia 
Ctenophora . . 
