BOTH THE SEXES IN DIPTERA. 



Si'c 



as a sensory organ. It liomologizes with the superior valves of the ovipositor in Tipula 

 or with the paired valves in 3Iusca, possibly with Huxley's " podical plate" in 

 Perlplaneta orientalls, Linn. 



{c) LaMIN/E superiores. 



structure. — This part consists of paired processes, often of a separate plate on tlie 

 anterior edge of the cavity containing the genitalia. Structurally it is strongly chitinized 

 and often with hooked bristles, sometimes with bunches of hair; so far as my observa- 

 tions have gone, the plate is always without spiracles. 



Nomenclature. — It is so called by Dziedzicki, who also names the segment on which 

 the part rests the " Lamina basalis." 



Ilycetophilldce. — It is well-marked in the genus Fhroiiia, but seems absent in other 

 genera of the Mycetophilidae, nor can it be differentiated in the Culicidge. 



TipulidcB. — It is obvious in Tipula oleracea, where the ventral edge of the abdomen 

 opposite the forcipes is studded with a number of tubercles ; but it does not seem 

 developed in the Stratiomyiidsp, Tabaaidae, Asilidae, Bombylidse, Empidae, Dolichopodidae, 

 or the Syrphidje (PI. 24. fig. 24). 



Muscidce. — In most of the Muscidse it is very evident and varies ^\ith species. In 

 Echinomyia fera (Linn.) and Phytomelaiiocej)hala, Meig., small plates with antei'ior clefts 

 are found. In Sarcophaga it is very marked, often having long hairy lateral processes 

 on the anterior edge, though in the nearly related Sarcophlla latifrons, Fall., it is hardly 

 perceptible. In Musca domestica, Linu., two marked lateral processes project, but in 

 Stomoxi/s calcitrans (Liun.) and Pollenia rudis, Fabr., only cleft hairy plates represent 

 the part. It can be ditferentiated, but is not prominent, in Calliphora enjihro- 

 cephala, Meig. 



In Glossiiia, where the whole of the last segment is turned in under the abdomen, 

 the forcipes inferiores rest against an arched horny baud which represents this part; 

 but in G. morsitans, Westw., where the whole ventral surface consists of a coriaceous 

 membrane without any chitinous plates, there is in the usual situation of this part a 

 lunule of chitin with strong short bristles thickly spread over it ; this is absent in 

 G. palpalis, Des. 



It has soft-haired, bulbous tubercles, small in size, in Morellia hortorum. Fall., 

 and Hyetodesia obscurata, Meig. In Hydrotcea, where the legs have many contrivances 

 for holding the female, it is but little developed. The most striking elaboration of the 

 part that I am acquainted with is on the abdomen of a small undetermined fly of the 

 genus Anthumyla that was common inside the houses in Maryborough, Queensland ; on 

 this insect are two pectinated arms, articulated on to the segment opposite the genitalia 

 (PL 26. fig. 60). 



Sejiskloi. — In an undetermined species of iSemopoda from Jersey this part is much 

 developed ; on it are two pairs of hairy ijrominences, a pair of membranous tubercles, 

 somewhat like palpi in structure, and a pair of barbs (PI. 29. tig. 103). 



Cordyluridie. — In Scatopliaya lllorea, I'all., and JSurellia spinimana are characteristic 

 developments of this part (PL 27. tig. 87 ; PL 28. fig. 1)7). 



