ANNALS 



OF 



The Entomological Society of America 



Volume XV MARCH. 1922 Number 



THE TERMINAL STRUCTURES OF ORTHOPTEROID 

 INSECTS: A PHYLOGENETIC STUDY 



E. M. Walker, 

 Toronto. 



PART II. 



The Terminal Abdominal Structures of the Male. 



The external genitalia of male insects are so variable in 

 structure even within the limits of a single family, that it is a 

 very difficult matter to trace the homologies of their component 

 parts; and much detailed study of many types from all orders 

 must be done before the subject can be placed upon a satis- 

 factory foundation. The difficulties experienced in the present 

 work in comparing the various types of Orthoptera alone have 

 been such that it was found desirable to give a relatively large 

 amount of time and space to this order, and as a result the 

 other orders have necessarily been somewhat sacrificed. Some 

 of them, such as the Plecoptera and Dermaptera, have been but 

 superficially treated, owing to lack of material. It is hoped 

 that these neglected groups will receive their due share of 

 attention at another time. 



In addition to the gentlemen to whom acknowledgments 

 were made in the Introduction to this paper, I have to thank 

 Mr. Morgan Hebard and Dr. R. J. Tillyard for the loan or 

 gift of specimens, and Prof. C. R. Crosby for the loan of books 

 from the Library of Cornell University. 



My chief regret in connection with the present investigation 

 is that much of the literature on the subject has been inaccessible 



