TJic Periodicity of Proyrcssii'c Mutations. 655 



XylonrCtuxum 



Kn^iih 



Fig. 149. Schematic pedigree of progressive formation of 

 species; based on Ocnotlicra LuDiarihi'ana. The upper 

 group is a reduced form of Fig. 148. and contains the 

 same new species. Onagra is the sub-genus to which 

 Ocnottiera Lainarcluana belongs. Euocnothcra, Ktiriffi*! 

 and Xyloptciiniui are other sulvgenera of Orih>tlii'iii. 

 The two small groups of lateral branches which ha\i- 

 been intercalated are intended to rcjirosent the sexrral 

 intermediate periods of mutation. Tlie figure can be 

 continued downwards in a similar manner. 



