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 the}^ are concerned in the act 

 of respiration. 



Besides the well known wingless genus Chionea, and the 

 Flea, Sheep-tick, and Braula, Loew, the eminent German ento- 

 mologist, enumerates several European species of Tipula, the 

 females of which have the wings rudinientar}- ; and also a spe- 

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

 sexes. " Ps^'llomyia, Apterina and Elachiptera, and species 

 of Tachista, Chersodromia and Geomyza have rudimentary 

 wings in both sexes ; in other forms the wings are only abbre- 

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

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

 Rhamphomjda, Idioptera and Tipula)." 



Fig. 270. Diagram of a iinng wlthtwo siihmar{/inul and five posterior cells (^Cladura 

 indivisa). Cells: — 1, costal; 2, subcostal; 3, marginal; 3*, inner marginal; 4, snb- 

 niarginal; 5, second submarginal; 0-10, first to fifth posterior; 11, discal; 12, first 

 li.isal; 13, second basal; 14, anal; 15, axillary; 10, spurious. Veins:— h I, auxiliary; 

 <■ 7», first longitudinal; h, n, o, second longitudinal; h i, prwfurca; k n, anterior 

 branch of tlic second longitudinal vein; k o, posterior branch of the s(!cond longl- 

 tiulinal vein; z /;, petiole of the first submarginal cell; ii^, third longitudinal; dq 

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

 tliis fork, ending in r, is 5Ir. Loew's anterior intercalary vein; s t, fork of the 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;/!?, sixth longitudinal; g w, 

 seventh longitudinal. Cross-veins: — .r, humeral; x x, subcostal; .cx.c, marginal; 

 X*, small, or anterior cross-vein ; x**, great cross-vein. — From Osten Sacken. 



e f 



Fig. 270. 



Fig. 271 (1). Wing of Ortalis. — a, transverse shoulder- vein ; 6, auxiliary vein; c, 

 ''> Ci ft 'i"f* '*> first, second, thii-d, fourth, fifth and sixth longitudinal veins; ?, 

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

 p, anterior basal transverse vein ; q, posterior ba.sal transverse vein ; r, rudiment 

 of tlie 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; 7, discal cell; A', first or large basal cell; L, second basal cell, or 



