BOTH THE SEXES IN DIPTERA. 341 



Cecidomylidce and MijcetophiUdce. — They are clearly present in the Cecidomyiidae and 

 the Mycetophilidse. In the genus Sc'iara they are quite valvular in appearance, and are 

 on the ventral side of the abdomen in their true inferior position (PI. 23. fig. 1). 



Bibio. — They are simple in Bibio and Scatopse (PI. 23. figs. 5, 7j. 



TipuUdcB. — In the Tipulidte they are remarkably developed. In Tipula oleracea, 

 Linn., the part consists of two hooks and a plate, forming an extraordinarily complicated 

 process (PL 24. fig. 25); the plate has a sense-organ, consisting of a number of socket- 

 like depressions and enclosed in a chitinous ring. In each socket is a membranous bulb 

 (PL 24. figs. 27, 28). 



Bhyplius. — The part is complicated and strongly chitinized in B. fenestraUs, Scop., 

 hairy and smaller than the f. superioresin R. pvnctatus, Fabr. 



Stratlomijiid(P. — In the Stratiomyiidfe, where the genitalia of the two sexes are 

 exteriorly much alike, these parts are simple and quite on the ventral side ; this is 

 markedly so in Chloromylaformosa, Scop., and Ilichrochrysa pol'ita (Linn.). 



Tabaniis. — In Tabanns bromius, Linn., two pairs of organs are found, and those on 

 the ventral side I homologize with this part ; they are normally bent at a right angle to 

 the median line, an unusual position (PL 29. fig. 109). 



Asil'uhe. — In the Asilidse they are smaller than the dorsal processes. In an un- 

 determined Australian Asilid the part has a hook articulated to it (PL 24. fig. 36). 



Empidce. — In the Empidae these parts are absent in B. stercorea, Linn., but are 

 represented as relatively small in most of the genera. 



Boliochopodidoi. — In the Dolichopodidge, where the " so-called fan " is well-developed, 

 this part appears to consist of two hyaline j^lates under the hypopygium (PL 25. fig. 43j. 



Syrphldo'. — They vary much in form in the Syrphidte, but are not complicated ; they 

 are usually simpler and much less developed than those in Syritta pipieiis (Linn.) 

 (PL 25. fig. 54). 



MiiscidtB. — In the whole of the Muscidae they are prominent on the dorsal side, and 

 form useful specific characters ; in Glossina at least four species can be differentiated 

 from these organs alone (PL 26. figs. 61, 65 ; PL 27. figs. 76, 77, 79, 80). 



Muscidce Acalyptratce. — They are also present in those families where, the female 

 having developed a telescopic horny ovipositor, the penis has been modified into a long 

 ribbon-like structure (PL 28. fig. 96). 



Romology with the ovipositor. — In the majority of flies these organs are on the eighth 

 segment of the abdomen, and correspond with the ventral egg-guides or valves of the 

 ovipositor, also on the eighth segment of the abdomen. This is very clear in Chlorunij/ia 

 formosa (Scop.). From their position, as Lowne points out *, they " correspond with tlie 

 inferior blades of the ovipositor in Locusto," or with the ventral valves in Tipiila 

 oleracea i. 



* Note.— In my two earlier papers on Scatophaga and Glossina I have called these parts the Forcipes superiores, 

 transposing the adjectives. As my studies had been confined to the iluscida?, where these hooks are always more 

 prominent, important, and articulated on the dorsal side of the hypopygium, this seemed the more reasonable 

 nomenclature. Study of the other families and of the ovipositor has enabled me definitely to settle the homology 

 of the part with that formulated t)y Dziedzicki. 



t ' Blow-fly,' p. 7:<2. 



.-)0* 



