5G 8T0M0XYS, AND OTHEK ALLIES. 



of the wings, the branched hairs on the arista, the bulb at the 

 base of the proboscis, and the remarkable male genitalia), Glossina 

 occupies a position altogether unique.* On the other hand, if 

 we consider the characters afforded by the proboscis and the 

 feathering of the arista, the affinity between Glossina and the 

 genera with which it is associated in the system of Brauer and 

 von Bergenstamm appears to be incontestable. The blood- 

 sucking habit is common to all, and correlated with this we find 

 a rigid, horny proboscis, which is carried in a horizontal position. 

 The palpi, however, which in Glossina are so remarkably modified 

 to form, in the living insect, a perfect sheath for the proboscis, 

 are in Stomoxys of the ordinary Muscid type, being exceedingly 

 slender, short (not projecting beyond the buccal cavity), and in 

 no way affording any protection to the proboscis. In Hsematolia, 

 as represented by H. siimulans, Mg., the palpi, while apparently 

 capable of forming a partial sheath for the proboscis, are dis- 

 tinctly shorter than that organ and expanded at the tips, while 

 the tip of the proboscis itself bears a few short hairs, and the 

 modified fleshy labella are plainly visible — as, though on a 

 smaller scale, they also are in the proboscis of Stomoxys. So far 

 as can be judged from Rondani's description and figure,f the 

 palpi and proboscis of Beccanmyia resemble those of Hsemafohia 

 stimulans, though the palpi do not appear to be expanded at the 

 tips. Lastly, in Lyperosia, Rond., as represented by Lyj)erosia 

 {Hsematobia) irritans, Linn., of Europe and North America, the 

 palpi, though flattened from side to side, as in Glossina, are not 

 expanded at the tips, while they form a complete sheath for the 

 proboscis, which they equal in length. As to the proboscis itself, 

 though the tip still bears a few minute hairs, the labella are 

 so reduced as to be practically invisible, their position, when 

 examined under a low power, being merely indicated by a slight 

 constriction, as in the case of the proboscis of Glossina. 



So far as regards pi-oboscis and palpi, therefore, Glossina 

 approaches Lijperosia more nearly than any other genus yet 

 mentioned. Moreover, in Hsematobia the arista bears three or four 

 short hairs on the under side as well as those on the upper, but 

 Lyperosia | agrees with Glossina in having the arista feathered 



* The aberrant mode of reproduction described by Col. Bruce (cf. 

 Chapter I., p. 24) forms a further proof of divergence, and constitutes an 

 approximation, so far as it goes, to tlie group of Diptera known as the 

 PupiPARA {Hippobosca, Ornithomyia, etc.). 



t " Ann. Mas. Civ. Gouov." iv. (1873), p. 287, 



X As also Sloinoxfjs. 



