864 ME. WALTER WESCHE ON THE GENITALIA OF 



DoUchopodkl(C. — In Bolichopus griseipennis and D. festivus the spiracles are in the 

 anterior part of the segment. 



Syrphid<s. — In Syritta this segment has no structure to notice except a single pair of 

 spiracles at the anterior part. 



Mtiscidce. — In Musca domestica three transverse setose plates at the posterior part of 

 the segment, anterior to them three fine long rods, two of which are fused together at 

 their anterior ends. I cannot find any sj)iracles on this segment (PI. 29. fig. 107). 



In CalUphora erythrocephala there is a dorsal plate opposed by a longer ventral plate ; 

 the posterior corners of the dorsal plate bear two pairs of spiracles close to each other. 

 This is a striking character, which I find also in ProtooalUphora groeiilandlca, Zett., and 

 Lucilia sericata, Meig., as well as in the Anthomyids, Hydrotcea dentipes (Fabr.), 

 Ophyra leucostoma, Wied., and Anthomyia plunialis, Linn. 



Folietes lardaria has no spiracles on this segment, the only structures being three 

 transverse setose plates. 



In JJlidia nigripennis, on this part are three plates, and a pair of spiracles is laterally 

 arranged (PL 28. fig. 96). 



Aberrant forms. — I shall now describe two ovipositors which are very unlike the 

 usual plan of the part. 



In the Tachinid Phorocera serrivenMs, Rond., or concinnata, Meig., a remarkable form 

 is found. The valvulge superiores are fused and formed into a single highly chitinized 

 hook, which is bent in under the abdomen and appears much like the penis in many 

 flies. Another process is found on one side with setae, and on the other side another 

 asymmetric part. Close to the hook are paired spiracles. The insect was in the vivi- 

 parous stage, the abdomen being full of fully-formed larvae (PI. 30. figs. 118, 119). 



Lauxania cenea, Eall., is also very divergent from the general type. The dorsal edge 

 is furnished with the usual paired organs (valvulae superiores) ; opposite these the ventral 

 plate is drawn out into a single strong lanceolate process, having on either side two 

 plates which may be the homologaes of the valvulse inferiores (PL 30. fig. 121). 



The Peceptacula seminis. 



Number. — The number of these organs varies from one to four ; but in the Muscidae 

 it is nearly always three. When the organ is single it is usually of large size. 



Nomenclature. — They are sometimes known as spermathecap, but Dufour calls them 

 " glandes sebiflques." I am under the impression that " receptacula seminis " is Lowne's 

 name for the parts. 



BiblonidcB. — In Pibio hortulanus and Biloplms febrilis (Linn.) they are three in 

 number and globiilar in shape. In Scatopse notata oval, relatively large, and single 

 (PL 23. figs. 3, 11). 



Chironomidce. — In a few females of Chironomus that I have examined I cannot find 

 any ; but in the genus Ceratopogon three are found. 



Cnlicidce and Tipulidce. — In the Culicidse and Tipulidae these organs are globular and 

 three in number. 



