The structure of the internal Genitalia of some 

 male Diptera 



by 



P. E. Keuchenius. 



With Plates XXIII— XXV. 



Introduction. 



The internal genitalapparatus of Diptera has been during the 

 last decennaries, a subject, that has not interested zoologists, there- 

 fore our knowledge of it may be called very incomplete. In this publi- 

 cation I state the results of my research of the male genitalia, while 

 in a following article (with which I have already made a beginning) 

 I hope to treat the female genitalia. 



For most of what is known to us at present aboiit the internal 

 genitalapparatus of Diptera, we are indebted to the extensive and 

 accurate work of Dufour (1851). In his work he acquainted us only 

 with the morphological structure of the genitalia. So far as I have 

 been able to verify, some of his descriptions are not quite correct, 

 which does not in any way detract from the value of his brilliant 

 researches. Besides the work of Dufoue, there exist still older re- 

 searches about the morphology of the internal genitalapparatus of 

 Diptera, written by e. g. Swammerdam (1752), Suckow (1828), 

 Meigen (1818 — 1838) and Loew (1841), while in the last decennaries 

 descriptions are known of only a few Diptera -species e. g. by 

 Stuhlmann (1905), Tüllock (1906) and Hewitt (1907). 



However, all the authors mentioned fail to give details about the 

 fine histological structure of the male genitalia, and our knowledge of 

 them is very scarce, compared with what is known about their mor- 

 phology. Of the histological structure we find descriptions concerning 

 Calliphora erythrocephala e. g. by Lowne (1895) and Brüel (1897), 

 while Cholodkovsky (1905) in his publication has written more com- 



Zeitschrift f. wissensch. Zoologie. CV. Bd. 33 



