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X. The Genitalia of both the Sexes in Diptera, and their Belation to the Ai-mature 

 of the 3Iouth. By Walter Wesche, F.B.3I.S. {Communicated by John 

 HoPKiNSON, Esq., F.L.S.) 



(Plates 23-30.) 



Eead 21st June, 1906. 



When, five years ago, I made some dissections of the genitalia of the males in 

 Scatophaga lutaria, Fabr. *, and ^S*. stercor^aria, Linn., I was much hampered by the 

 absence of any systematic nomenclature. Huxley, in his ' Anatomy of Invertebrated 

 Animals,' passed by the genitalia of the male cockroach with a mere allusion to the 

 complexity of the parts t. 



L. Dufour X in his, at all events, comprehensive review of the genitalia in Diptera, 

 never attempts to grapple with the separate parts, contenting himself by saying: 

 " L'armature copulatrice, receptacle de la verge, est une machine des plus compliques, 

 destinee a se porter hors un corps lors de I'union des sexes. Les nombreuses pieces 

 plus ou moins symetriques, cornees ou coriacees qui la composent, combinent leur action, 

 soit entre elles, soit avec les organes cxternes de la femelle pour consommer I'acte de la 



fecondation." 



Packard is no help, either in his larger works, or in his small paper on the homologies 

 of the ovipositor and the homologous parts in the male insect §. 



Kirby and Spence classify the ovipositors, giving them some very unwieldy names, 

 but make no analysis of the pa,rts of the male || ; an omission to be regretted, as they 

 are, at the least, of equal interest, and in their way of equal symmetry and beauty, with 

 the armature of the mouth-parts, though more difficult to dissect out. 



But in a paper on the genus Fhronia of the Mycetophilidoe by A. Dziedzicki^ I 

 found a scheme of nomenclature for the external valves of the genitalia of both sexes, 

 but not for the complicated parts that are attached to the penis of the male, that 

 combination being caUed the " appendix interna " or " adminiculum." The only careful 

 and complete study of this part exists in Dr. B. Thompson Lowne's monograph on the 

 Blow-fly ** ; he has named all the parts as they exist in this insect, and given admirable 

 figures of the male armature, drawn on a large scale, so as to be easy of comprehension. 

 So with the material drawn from Dziedzicki, from Lowne, and a small contribution 

 from Miall and Denny's ' Cockroach,' and my own resources, I am able to formulate a 



* Journal of Quekett Micr. Club, April 1903. t p. 350 (1877 edition). 



t "Recherches anatomiques at physiologiques sur les Diptercs," 1851, Mem. Pres. Ac. Kci. Paris, tome xi. 



p. 198. 



§ Proc. Boston Soc. Nat. Hist., xi. 1868. 

 II Description of plates 15 & 16, 1828 edition. 

 ^ Hor. Soc. Entom. Ross., tome xxiii. 1889. 

 *• ' The Anatomy, Physiology, Morphology, and Development of the Blow-fly,' 1895. 



SECOND SERIES. — ZOOLOGY, VOL. IX. 5" 



