;N^0. 64] DIPTERA OF CONNECTICUT: MORPHOLOGY 111 



into the common ejacnlatory duct. In all of the Cyclorrhapha exam- 

 ined by the writer (including a series from the Syrphidae to the 

 higher muscoid types) this common efferent duct, ed^ loops up from 

 the insect's left side over the top of the hind gut (see Fig. 14, H, and 

 Fig. 9a, A) to the insect's right side before it discharges ventrally 

 through the aedeagus, and this fact is "proof positive" that the ninth 

 segment undergoes a circumversion (^yhile the eighth sternite becomes 

 inverted) in a clockwise direction in these flies, as was mentioned be- 

 fore. 



The surstyli or edita, 55, of Fig. 13, E, of PoUenia., or Fig. 13, D, 

 of Hylemyia, etc., are "appendages" of the ninth tergite which serve 

 as accessory claspers in mating. The}^ are Avell developed in such 

 lower Diptera as the ptycliopterid Bittacomor-'pha shown in Fig. 10, K, 

 and are quite long in certain anthomyids such as the one shown m 

 Fig. 7, K, while in the housefly shown in Fig. 10, L, they are broad 

 and stout, and have the appearance of a divided sternite of the genital 

 segment for which they were mistaken by Berlese (1909) and Hewitt 

 (1914). 



The surstyli, 55, of Fig. 13, E, and Fig. 13, D, are designated as 

 the styli of the "gonopods" (i. e., the distimeres of the genital for- 

 ceps) by Hendel (1928) in his diagram of the terminalia of a typical 

 schizophoran, and Awati (1915) also considers that the surstyli of 

 the Cyclorrhapha represent the so-called "genital styles" (or distal 

 segments of the genital forceps) of the lower Diptera, in which, ac- 

 cording to Awati, the basal segments of the forceps {cxi of Fig. 12, G) 

 represent the divided "ninth sternite". Metcalf (1921) likewise refers 

 to the surstyli as the "styli" in the Syrphidae, and Berlese (1909) 

 calls them the mesostyli in the syrphids. Huckett (1924) homologizes 

 the surstjdi with the distimeres or dististyli (distal segments of the 

 genital forceps) in the anthomyids. and Cole (1927) considers that 

 the surstyli represent the distal segments of the genital forceps in 

 some cases, and homologizes them with the distimeres, or so-called 

 harpes, harpagones, etc., of lower Diptera, Patton (1932-1935), on the 

 other hand, homologizes the surstyli with the "coxites", or basimeres 

 of the genital forceps of the lower Diptera, and all of these investi- 

 gators regard the surstyli as parts of the genital forceps of the lower 

 Diptera, although the surstyli are appendages of the ninth tergite, 

 while the genital forceps of the lower Diptera are sternal structures 

 homologous with the parameres of the Hymen optera and Coleoptera. 



Balfour-Browne (1932) considers that the surstyli, 55, and cerci, 

 <?e, of Fig. 13, E, are parts of the same structure in the blowfly, and 

 Lowne (1895) refers to the cerci and surstyli as the internal and 

 external valves of the "progenital" segment in the blowfly. Wesche 

 (1906) refers to the surstyli as the forcipes inferiores in the higher 

 Diptera, and Newstead (1911) calls them the edita in Glossina. 

 Wesche (1906) states that the surstyli have been called the zygapoph- 

 yses and claspers by some investigators, and Hendel (1928) states 

 that they are called the paralobes by Pandelle, and the valvulae later- 

 ales by Schraeder. 



