BOTH THE SEXES IN DIPTERA. 351 



above name for the same reasons as in the case of the forcipes interiores. They are 

 only anterior so far as regards the penis itself — as regards the insect, they are often, as in 

 Lollchopiis in posterior positions. 



Bibionlda;. — In Bibio hortulamis I think these organs are represented by the bands 

 supporting the penis (PL 23. fig. 4). In Scalopse notala their extremities are columnar, 

 springing from a broader base ; the column is capped by a bunch of sensory hairs, and 

 there is a seta lower down (PI. 23. tig. 6). 



Tipulklce. — It is impossible with the facts at my command to say definitely that the 

 lateral arms of the theca in Tipula oleracea are not these organs, but at all events 

 their function seems supplied by the bunches of setae on the dorsal sides of the abdomen 

 (PI. 24. fig. 24). They seem absent in Flijchoptera scutellaris. 



Bolichopodidce. — I cannot identify these organs among the related families till we 

 reach the Dolichopodidse. In the genera DoUchopus and Foecllobothrus, in the 

 remarkable group of weapons situated between the forcipes superiores and the forcipes 

 inferiores, are generally a pair of smooth large-headed organs with sensory setae (PI. 25. 

 fig. 47) ; also a pair with a leaf-like venation, whose presence is not easy to account for 

 (PL 25. fig. 48). 



Si/rphklce. — In Catahomba pyrastrl they are two hairy plates articulated to the theca 

 (PL 25. fig. 53). In Syritta jiipkns they seem atrophying, being represented by two 

 weak lateral bands, which, however, carry a sense-organ (PL 26. figs. 56, 57). In 

 Eristalis tenax they seem quite atrophied, two minute tubercles carrying scattered 

 setce only remaining. 



Miiscidce. — In the Muscidse they are at their greatest and most characteristic 

 stage, but are occasionally absent, as in Olioieria lateralis, where small tubercles and 

 bristles mark their site (PL 29. fig. 112). In Sarcophaga carnarla they are developed, 

 but more of a hook shape, and though they are studded with hair-sockets, the hairs 

 appear to be absent, but the inner side of the part appears to be soft and membranous 

 (PL 26. fig. 60). In Follenia rudis, Pabr., tlicy are very characteristic both in shape 

 and pubescence (PL 26. fig. 62). They are approximately of the same type in Callip//ora 

 erythrocepluda, in Lucilia ccesar, Linn., and in Anthomyia radlcmn. In Glossina they 

 are not articulated, and are fused with the forcipes interiores in G. paljjulis and 

 G. tachinoides (PL 27. fig. 86) ; in the former species they carry most remarkable 

 hairs *. In G. pallidipes, Austen, they are two broad plates with very long fine hair 

 arranged symmetrically on the anterior side of the central organ (PL 27. fig. 78). 



In the Cordyluridne the parts often cirry long seta; as in Scatophaga litorea. Fall. 

 In Norcllia spiiilmana, Pall., they seem to have exchanged places and functions as well 

 as shape with the forcipes (PL 28. fig. 89). In Facellia fucornm, Fall., they are absent, 

 their places, exactly as in OUcieria, being marked by single bristles. 



LonchmdcE. — They can be traced in L. nigrimana and Toxoiieura miillebris at the base 

 of the penis, probably in an atrophying state (PL 30. fig. 122). 



Sepsldce. — In Sepsis and Nemopoda they seem absent, tliough I have an imperfect 



* "Genitalia of the Tsetse-fly, Qlossina palpalis," Journ. Quek. ilicr. Club, Nov. 1905, p. 236. 



