G. C. CRAMPTON 207 



THE GENITALIA OF MALE DIPTERA AND MECOPTERA 



COMPARED WITH THOSE OF RELATED INSECTS, 



FROM THE STANDPOINT OF PHYLOGENY 



BY G. C. CRAMPTON 



MdSKdcliiiscUs AgricuUurdl CoUrge, Amherst, MasfiucJtusetfs 



For identifications and material of Diptera, I am deeply in- 

 deljted to Dr. C. P. Alexander, Dr. J. M. Aldrich, and Dr. C. W. 

 Johnson, and I am likewise deeply indebted to Dr. Bethune- 

 Baker for the loan of a specimen of Micropferyx (EriocephaJa) 

 caUheUa, and to Dr. P. A. Bnxton, for a fine series of Micropteryx 

 (EriocephaJa) sepella. 



There have been published a number of papers dealing with 

 the genitalia of male Diptera, such as the fine pa])er by Metcah" 

 on the Syrphidae, Snodgrass on the Tipuhdae, Edwards on the 

 Culicidae, etc., and several investigators such as Berlese, Crami> 

 ton, Newell, Wesche, and others have compared the parts of 

 the genitalia of male Diptera with those of lower insects. In 

 most cases, however, no attempt has been made to trace the 

 origin of the modifications met with in the Diptera through a 

 series of intermediate forms to a basic plan common to all 

 insects, and until this is done, we cannot arrive at a correct 

 interpretation of the parts in the Diptera and related forms. 

 I would therefore use as the l)asis of th(; following discussion, 

 the fundamental plan of the genitalia of male insects in general, 

 described in the Canadian Entomologist,^ and I would trace the 

 modifications of this fundamental plan through the Hymenop- 

 tera and Mecoptera (which furnish the intermediate types, 

 connecting the Diptera with the lower forms) to the dipteran 

 types, giving consideration to the conditions met with in certain 

 Hemii)teia, Lepidoptera, Trichoptera, etc., when the condition 

 exhibited l)y these forms has a liearing upon the interin-etation 

 of the parts in the Diptera. 



1 LIl, 1920,1) 180— see also correction on p.-igo 72 of ]JII, 1921. 



TRANS. .AM. KXT. SOC, XLVUI. 



