BOTH THE SEXES IN DIPTEEA. 361 



at their base — these are the valvulae siiperiores ; the valvulae int'eriores seem atrophied, 

 but there are signs in the interior of P. albimana of the presence of the lamella 

 anterior. 



Stratiomyiidcc. — In Beris oallata the valvulae superiores are two-jointed, which is very 

 uiju«ual, the valvula? inferiores very minute, a similar arrangement existing in B. nigra, 

 Meig. (PI. 24. figs. 34-, 35). In Stmdonij/s chamcBleon all the parts are present but 

 relatively small. The valvulae superiores have a curious sense-organ on the apex. 



Tabanidte. — In Tabamis boviims, Linn., all the valves are hairy, and, as in aS*. chamceleoii, 

 relatively small ; the valvulae inferiores appear to have fused, but the plate is notched 

 on the median line (PI. 30. fig. 126). 



Empidce. — In SUara cilipes only a pair of hairy processes are present (PI. 25. fig. 42). 

 In Empis cliioptera, Pall., these processes are adhering to a membrane, the segment or 

 apparent segment consisting of a dorsal and a ventral plate. These may represent the 

 other valves and plate. 



DoUchopodidcB. — In DoUchoptis a very remarkable development of this part is found ; 

 two horny valves (v. superiores) are laterally placed, and below them are two ciliated 

 lunules (v. inferiores). The valvulae superiores are articulated on to a plate, cleft in the 

 middle ; on this is a remarkable series of blunt spines, presumably of use in coitus 

 (PI. 25. fig. 52). They are a feature of the ovipositor in this family, and are often 

 double and treble the length of those in _D. grlseipennls. These contrivances for 

 holding the partner in coitus, common enough in the male, are quite rare in the other 

 sex. In the Bombylid Comptosia ocellata. New., the valvulae inferiores have a number 

 of long blunt hooks, Pegomijia bicolor has pads of hair, and Norellia .spininiana (to 

 which I shall again refer) has rows of short blunt spines on the abdomen (PI. 28. fig. 90). 



Sijrphid(e. — In the Syrphidae the valves are hairy and rather insignificant, but the 

 plate is difficult to differentiate. 



Muscidce. — In the calyptrate Muscidae the dorsal valves are liairy ; they are opposite 

 to a plate which is probably a fusion of the ventral valves, and they are attached to 

 a strip of cliitin which has, and sometimes has not, a suture in the middle (Mitscu 

 domestica and Calliphora erythrocepJiala) (PI. 29. fig. 106). 



When the ovipositor is of the Ortalid type, generally a pair of hard short valves are 

 present, carrying a few sensory setae, the remaining parts not being distinguishable 

 (PI. 28. fig. 95). 



Cordyluridce. — In Snatopihaga stercoraria the valvulae superiores arc very haii-y and 

 each carries a long seta ; the valvulfc inferiores are hoi'ny plates, genuine egg-guides, 

 and the lamella is well-marked (PI. 30. fig. 131). 



In Norellia spinimana are only two setose valves and two plates (PI. 28. fig. 90). 



Geotmjzidce. — In Anthomyza pallida, Zett., the valvulae are peculiar ; they are 

 chitinous pLitcs, studded with blunt spines ; opposite to them arc two valves; the plate 

 is difficult to diflFerentiate in my preparations (PI. 28. fig. 100). In an unnamed slide 

 in my collection (an Anthoniyid) the dorsal valves have two short, strong, socketed 

 setae on each, besides many hairs ; the otlicr parts are of the Musca domestica type, 

 but with very fine rods. 



A 



