268 Annals Entomological Society of America [Vol. XII, 



and species, but the specialist is seldom interested in these 

 structures except in so far as they afford good taxonomic 

 characters in the groups with which he is concerned, and does 

 not trouble himself to inquire into their homologies with the 

 corresponding parts in other orders. The natural result of 

 this is a multiplicity of terms and a great lack of unanimity 

 in their application. 



The most fundamental upheaval of our generally accepted 

 ideas of insect classification that has occurred in comparatively 

 recent years is the system advocated by the eminent student 

 of fossil insects, Anton Handlirsch. This system, which was 

 first proposed in 1903,^ and elaborated in 1908 in his monu- 

 mental work, "Die fossilen Insekten, " is well known, and its 

 deviations from previously accepted views are due mainly 

 to the study of the fossil record. His division of the old class 

 Insecta (Hexapoda) into five classes — Collembola, Campo- 

 deoidea, Protura, Thysanura and Pterygogenea — is not based 

 directly upon palaeontological evidence, but on general con- 

 siderations of structure; but the splitting up of the old order 

 Orthoptera is founded upon the actual fossil record, so that the 

 question as to whether or not the findings of comparative 

 morphology support his views becomes one of considerable 

 importance. 



The present study of the genitalia and associated parts of 

 the groups commonly called Orthoptera is offered as a con- 

 tribution to this subject and, at the same time, an effort has 

 been made to clear up certain general questions on the homolo- 

 gies of the parts concerned. 



Before proceeding with the discussion of the terminal 

 abdominal structures, it may be useful to give a brief summary 

 of Handlirsch's views in so far as they relate to the origin and 

 relationships of the various groups still commonly known as 

 Orthoptera, i. e., the Blattidse, Mantidce, Phasmidse, Acrididae 

 and Acrydiidse (Tettigidas)*, together with such other groups as 

 may appear to be more or less closely related to them. 



The earliest undoubted insect remains belong to the Car- 

 boniferous era. They are all winged insects of comparatively 

 large size, some of them very large. Eleven orders are recog- 



1 Handlirsch, 1903. Zur Phylogenie der Hexapoden. Vorlaufige Mitteilung. 

 Sitzb. K. Akad. Wiss., Bd. 112, Heft 8, Abt. 1, pp. 716-738, Taf. 1. 

 * The Acrydiidae of Most Authors. 



