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THE AMERICAN NATURALIST [Vol. XL V 



Much more striking evidence upon the matter has been 

 recently obtained by Tower in intercrossing Leptinotarsa 

 decemlineata, L. multitineata, L. oblongata and other 

 species in their habitats in southern Mexico, and at the 

 desert laboratory. Among other divergences one of the 

 three first generation intermediates characteristic of 

 these cultures was lacking from the Tucson cultures, 

 although two other such forms were included. 10 In a 



comprehensive treatment of the entire subject with espe- 

 cial reference to modifications in dominance Tower says : 



