178 



THE AMEBIC AX NATURALIST [Vol. LIU 



from isopod forebears, but the sympbylid and isopod 

 characters which appear in certain insects were inherited 

 from their ultimately common ancestry, and the relative 

 positions of the different ancestors of insects in the ''he- 

 reditary areas" of this common ancestry {i. e., whether 

 their hereditary areas were contiguous to those of the 

 ancestors of isopods or to the ancestors of the Symphyla, 

 etc.) determines whether certain of the insects descended 

 from them shall resemble isopods or S>Tiiphyla, etc., and 

 the same principle applies in the successively larger as 

 well as in the smaller groups of living things. 



EEFEREXCES CITED 

 The Morphology of Triarthrus. Amer. Jour. Scl, 16, p. 166. 

 The Apoaida\ 



