ground, that, upon the form of the genitalh the segregation 

 of species depends, and, further, that changes in the 

 process of development, which would amount to the 

 formation of a new species, must of necessity be reflected 

 in the form of the genitalia, if that development is to be 

 made permanent. Thus, while fully admitting that the 

 final classification can only be arrived at upon the study 

 of all the characters, we feel confident that the present 

 arrangement marks a big step towards the goal, and our 

 confidence is strengthened by the close agreement of our 

 results with those of Mr. E. Meyrick, which were reached 

 by the study of other structural characters. 



A word must be said with regard to the names 

 employed for the different parts of the genitalia. The most 

 recent work of importance on the subject is contained in 

 Professor N. J. Kusnezov's " Introduction to the Fauna 

 of Kussia," Petrograd, 1915, wherein ha treats of the 

 names of the parts as used by various authors. This work 

 was published directly after the publication of " The 

 Genitalia of the British GeometridcE," but the author was 

 only acquainted with the previous volume en the British 

 Noctuidcv. We are therefore unable to accept his names 

 for the parts that had already been named in ' The 

 Genitalia of the British Geometridcc." 



After full consideration of what has been written in 

 criticism of the names employed in that work, we find no 

 reason for changing them, and we accordingly employ them 

 in this present volume, referring our readers to the former 

 for definitions and descriptions. We are quite 

 satisfied that the parts of the Tortricid genitalia 

 are homologous with those found in the Geometridce, and 

 we are averse to creating new names for mere 

 modifications of the same organs. Some day it 

 may come to be generally recognised, that, as we believe, 

 the genitalia in all orders of insects are built upon a common 



