394 
(4) Genus Stomoxys. — (a) Palpi very small, bear¬ 
ing some hairs; not projecting beyond the epistome. 
( b ) Proboscis is bent at its base like an elbow joint. 
{c) Arista plumose dorsally, distally forms a fine hair. 
(d) Third and fourth long veins reach the apex. The 
fourth is bent beyond the posterior cross vein. Wings 
diverge widely. 
S. calcitrans .—The £ stable 5 fly, is common about 
farm yards. 
Fig. 125. Stomoxys, shewing resting position 
of Wings, x 2. (After Austen) 
Structure of Proboscis .—In Stomoxys calcitrans as 
in Qlossina the cutting mechanism of the proboscis 
lies in the labella. The structure of these is even 
more complex than in Glossina, but consists essentially 
of five very strong teeth on each side. These can be 
completely everted and by rotation of the proboscis 
tear through the skin. The proboscis proper consists 
of ( a ) labrum, ( b ) labium, and (c) hypopharynx. The 
relationship of these parts is shewn in the figure. 
(5) Genus Glossina {tsetse-flies)* — Abdomen 
generally, but not always, has pale but well-marked 
dark-brown bands interrupted in the middle. 
* The data of this section are compiled from A Monograph of the Tsetse Flies, 
by E. E. Austen, and from an article in the British Medical Journal , September 17, 
1904, by E. E. Austen. 
