i8 4 
explanation of PLATE XII 
E^ - 1 ‘ External mouth parts of Stomoxys calcitrans seen from the 
side, x 36, about, a , labrum; a 1 , ventral ridge of labrum 
bearing sensory hairs; a 1 , dorsal hairs ; b, hypopharynx; 
c, labium; c 1 , labella ; g, palpi; h, apodeme of labrum; 
i, large tracheal tube or sac. 
Flg - 2 —Labella everted, dorsal aspect. The left half shows the 
characteristic scale-like structure of the epidermis. x200- 
F, g- 3 - Labella everted, ventral aspect. Details of epidermis omitted, 
x 200. 
big. 4—Labella closed, dorsal aspect, x 200. 
Fig. 5.—Labella closed, ventral aspect, x 200. 
