58 SPECIALISATION IN WING OF GLOSSINA. 



and Eclmiomyia, since the former have an exposed, the latter a 

 protected metathoracic stigma. In venation, however, Glosstna 

 is more specialised than the Anthomyinse that in Girschner's 

 arrangement are grouped with it, since it is provided with a 

 " Spitzenquerader " (bent-iip terminal portion of the fourth vein), 

 which, joining the margin of the wing before the apex, leaves 

 the latter entirely membranous ; this condition is in Girschner's 

 opinion a protection to the veins in most intimate connection 

 with the respiratory system.* In respect of venation, too, as 

 also in having the membrane of the wings rilled instead of smooth,"]" 

 Glossina is more specialised than its immediate allies, Stomoxys, 

 Hiematdbia and Lyperosia, in which the third and fourth veins 

 both reach the apex of the wing, the fourth vein being only 

 slightly bent up at its extreme tip, well beyond the posterior 

 transverse vein, while the membrane of the wings is not 

 rilled. 



It is stated by Girschner J that the chastotaxy of the sterno- 

 pleurae in his family " Anthomyidse " (which includes the groups 

 " Coenosiinse " and "Muscin?e") differs very much, and is even 

 variable in the species of the same genus, so that it is of only 

 subordinate value for systematic purposes. The author in 

 question goes on to say : — "It is, however, characteristic of all 

 Anthomyids that, in the cases in which the sternopleura shows 

 only three macrochtetse, the order of arrangement is invariably 

 1 : 2, i.e. the larger number of bristles always occurs on the hind 

 border of the sternopleux'a." As will be seen from Fig. 1 1, p. 69, this 

 is precisely what we find in the case of Glossina. In Girschner's 

 family " Tachinidpe," however, when three sternopleural bristles 

 are present, the characteristic arrangement is always 2:1, or 

 the three bristles stand in a row, as in Sarcophaga and 

 Brachycoma.^ 



In conclusion, since Girschner has introduced an element of 

 confusion by employing old family names in new senses, it is 

 sufficient for present purposes to remember that, in terms of the 

 simplest taxonomy, the genus Glossina belongs to the sub-family 



* Cp. Girschner, loc. cit. pp. 299-300. 



t Cf. Hough, " Biological Bulletin," Vol. I. (1899), p. 20, note 1 :— 

 " These rills are very fine grooves in the surface of the wing which run in 

 a sort of radiate manner toward the border. They are very numerous. A 

 rilled wing denotes a higher stage of development, a more recent form, 

 than an unrilled wing." 



X Loc. cit. p. 302. 



§ Girschner, loc. cil. p. 303. 



