1918] 



Morphology of Genitalia of Insects 



129 



tive pairs of genitalia, a most generalized condition. The use of 

 the word generalized may be objected to in a case of such 

 extreme specialization, but certainly the relation between 

 somites and appendages is a primitive characteristic in itself, 

 and one extremely prominent in this group. 



Table of Sclerites and Appendages. 



SOMITES appendages 



Hepialus humuli 7, 8, 9, 10, 11 I, II, III, IV. 



Female t+ t+ t4- t+ t— +* — — — 



s+ s+ s+ s+ s — 



Male t+ t+ t+ t+ t— + _ _ _ 



s+ s-\- s+ s+ s — 

 Pryonoxystus robinice 



Female t+ t+ t+ t+ t+ _ _ _ _ 



S+ S+ S+ S+ S.+ 



Male t+ t+ t+ t+ t+ + + + — 



s+ s+ s+ s+ s+ 

 A gratis ypsilon 



Female t+ t+ t+ t+ t+ _ _ _ _ 



s+ s+ s+ s4- s+ 



Male t+ t+ t+ t+ t— + + + — 



s+ s+ s+ s+ s — 

 Anosia plexippus 



Female t+ t+ t+ t+ t— _ _ _ _ 



s+ s+ s+ s+ s — 



Male t+ t+ t+ t+ t— + + + — 



s+ s+ s+ s+ s — 

 Phlegethontius sexta 



Female t+ t+ t+ t+ t+ _ _ _ — 



s+ s+ s+ s+ s+ 



Male t+ t+ t+ t+ t+ + + + — 



s+ s+ s+ s+ s+ 



i. Diptera. — The Diptera differ among themselves largely in 

 presenting both very generalized and specialized conditions. 

 The specialization, so far as appendages is concerned, is again 

 one of reduction. The best illustration of generalization is seen 

 in the female of Tipula abdominalis and specialization is evident 

 in the tabanid. A caudal view (Plate XVI) illustrates extreme 

 specialization by reduction with scarcely any appendages indi- 

 cated except the cerci, Appendage IV. In this as well as in all 

 cases of this type of specialization both the anal and the genital 

 openings occupy their typical position. The male shows greater 

 specialization both in Appendage IV and in the other appen- 

 dages, especially in the one forming the case for the ejaculatory 

 duct, Appendage II, but even here, comparatively speaking, 

 specialization by modification and enlargement of parts is 

 fairly slight. 



