360 DIPTERA. 



The function of the halteres, or "poisers," is still problema- 

 tical. Hicks and Leydig consider them as organs of hearing, 

 while Goureau and Loew think they are concerned in the act 

 of respiration. 



Besides the avcU known Avingiess genns Chionea, and the 

 Flea, 8Iieep-tick, and Braula, Loew, the eminent German ento- 

 mologist, enumerates se-s^eral European species of Tipula, the 

 females of wliieh have the wings rudimentar}^ ; and also a spe- 

 cies of Limnolna (Idioptera). Epidapus is wingless in both 

 sexes. "Psyllom^'ia, Apterina and Elachiptera, and species 

 of Tachista, Chersodromia and Geomyza have rudimentary 

 wings in both sexes ; in other forms the wings are onl}- abbre- 

 viated in both sexes CSciomyza), or in those of the male or fe- 

 male are smaller than in the other sex (species of Empis, 

 Ehamphomyia, Idioptera and Tipula)." 



Fig. 270. Diagram of a wing loith two subniarginal and Jive posterior cells ( Cladura 

 indivisa). Cells: — 1, costal; 2, siibcostal; 3, marginal; 3*, iiiuer marginal; 4, sub- 

 marginal; 5, second subniarginal ; C-10, first to fifth posterior; 11, discal; 12, first 

 basal; 13, second basal; 14, anal; 15, axillary; 16, spurious. Veins : — b I, auxiliary; 

 c m, first longitudinal ; 7i, n, o, second longitudinal ; h i, prsefurca ; Jc n, anterior 

 branch of the second longitudinal vein; k o, posterior branch of the second longi- 

 tudinal vein; «7j, petiole of the fii-st submarginal cell; ip, third longitudinal; dq 

 rs t, fourth longitudinal; q r, fork of its anterior branch; the posterior branch of 

 this fork, ending in r, is INIr. Loew's anterior intercalary vein ; s f, fork of tlie pos- 

 terior branch of the fourth vein ; the branch of this fork, ending in t, is Mr. Loew's 

 posterior intercalary vein; e «, fifth longitudinal; / r, sixth longitudinal; g w, 

 seventli longitudinal. Cross-veins: — a:, humeral; x x, subcostal; vCa-x, marginal; 

 X*, small, or anterior cross-vein; a;**, gre;at cross-vein. — From Osten SacJcen. 



Fig. 270. 



Fig. 271 (1). Wing of Ortalis. — a, transverse shoiilder-vein ; b, auxiliaiy vein; c, 

 d, e, f, g and h, first, second, third, fourth, fifth and sixth longitudinal veins; i, 

 small or middle transverse vein; Ic, hinder transverse vein; ?, m, n, o, costal vein; 

 p, anterior basal transverse vein; q, posterior basal transverse vein; r, nidiment 

 of the fourth trunk; s, axillary incision ; A, B, and C, first, second and third costal 

 cells; D, marginal cell; E, submarginal cell; F, G and H, first, second and third 

 posterior cells; /, discal cell; A', first or large basal cell; X, second basal cell, or 



