160 THE AMERICAN NATURALIST [Vol. LVI 



The classes into which the families are grouped are as 

 follows: Phytophaga, Saprophaga and Harpactophaga. 

 In addition to these three important ones, the species 

 attacking mammals and those whose family habits are 



obscure have been grouped separately. In the Phytoph- 

 aga have been placed those species which feed upon 

 the higher plants. In the Saprophaga will be found 

 those forms which feed for the most part upon disor- 

 ganized tissue, vegetable and animal decay and such 



