264 



H. TETLEY. 



hairy, more pointed than in the female, and has no central strengthening rod of 

 chitin. Its breadth is covered with rows of minute hairs or spines which lie in a 

 direction perpendicular to the edge of the blade. On either side of the apex is an 

 area free from hairs (fig. 10), in which lie the curved rod-like structures shown in 

 the figure. 



(4). Hypopharynx (text-fig. 11). — This has the apex much broader than in the female, 

 and it ends abruptly and does not taper. The salivary duct runs down the middle 

 and opens at a distance of *4 mm. from the apex. 



Fig. 11. Apex of hypopharynx of <$ ; 

 greatly enlarged. 



(5). Labium, — Similar to that of the female, except that the teeth on the pseudo- 

 tracheae of the labella seem to be rather more slender as a rule, but the difference is 

 very slight. 



IV. Measurements, 



in 



Millimetres, of the Mouth-parts of both Sexes. 









Labium. 



Mandibles. 



Maxillae. 



l 



Hypo- 

 pharynx. 



Lbrepi- 

 pharynx* 





$ 



? 



<J 



$ 



$ 



? 



3 



? 



<J 



? 



Length 



»j • 

 Greatest width 



Width in 

 middle . 



47 

 42*5 



49 

 42 



— 



left right 

 10 10 



•53 -54 

 •30 -30 



left right 

 9*5 9-5 



•24 -30 

 •14 -16 



left right 

 9-8 9-6 



•35 -37 

 •18 -13 



9-5 

 •40 



9'5 



•40 

 •10 



9-5 



1-04 



•58 



9-3 



•66 

 •46 



V. Conclusions as to the Feeding-habits of the Species, 



From an examination of the mouth-parts of both sexes of Pangonia longirostris 

 it will be seen that the sexual differences are : — 



(1) That mandibles are completely absent in the male (as in all other male 

 Tabanidae), but are present in the female as strong organs toothed at their apices. 



(2) The maxillae of the male are loosely attached to the head, lying in a membranous 

 area and with no articulation with the head skeleton, and are hairy to the apex ; 



