The Mouth-parts of the Nemocera, etc. By W. Wesche. 33 



I find some characters exist, but they are of so minute a 

 nature, and depend so much for their visibility on the way in 

 which they have been mounted, that they are of little or no value 

 in differentiating species. Yet there is one character that sharply 

 separates Anopheles from the other genera: the mandibles are 

 serrated at the tip. This part in the other species seems in an 

 atrophying state, and is often exceedingly difficult to make out. 

 The rare presence of the mandibles in the males, I shall discuss 

 in Group 2, to which section they belong. 



Tor an excellent description and plate of the mouth-parts of 

 Anopheles maculipennis, I refer the reader to Dr. G. H. F. Nuttall's 

 and Mr. A. E. Shipley's paper on the " Structure and Biology of 

 Anopheles." * 



In the Culicidse, omitting Corethra, the parts are specialised 

 for blood-sucking, and especially the blood of man. An examina- 

 tion of the tropin of another pest, Cimex lectidaria, shows an 

 interesting correspondence in the fine serration and delicate struc- 

 ture of the maxilla?, enabling the insects to punrture the skin 

 without inflicting pain, or attracting the attention of the victim. 



In the female C. pipiens, the maxillary palpi are apparently 

 two-jointed, but I can trace the remains of two more on the lower 

 joint, making them conform to the Nemocera type of four joints. 



In the Brachycera, are the Tabanidre ; they have been so 

 much studied that little need be said about their very beautiful 

 tropin. I have figured Chrysops ccvcutiens L. (pi. IV. fig. 2), as 

 there are on the dorsal side of the labium two short rows of hairs, 



* Journal of Hygiene, i. No. 4, 1901, p. 461, pi. ix. 



EXPLANATION OF PLATE IV. 



1. Trophi of Pangoniq lonyirostris $. Seen from the dorsal side. 



2. Maxilla and palpus of Chrysops excutiens L. 



3. Mandible of C- excutiens. 



4. Labium of C. excutiens. Dorsal view, showing the palpigers. 



5. Palpigera of C excutiens, enlarged. 



0. Labrum and liypopharynx of C. excutiens. 



7. Maxilla and palpus of Simulium reptans L. 



8. Mandible of S. reptans. 



9. Labium, with two minute teeth, of S. reptans. 



10. Hypopharynx of 8. reptans. 



11. Labium of S reptans. In the centre is seen the wrinkled membraue, which is 



possibly the epipharynx, Dors-U view. 



12. Maxilla and palpus of Asitus crabroniformis L. 

 I'd. Mandible of A. crabroniformis. 



14. Labium of A. crabroniformis. Lateral view. 



15. Labrum of A. crabroniformis. Dorsal view. 



16. Ciliated hypophannx of A. crabroniformis. 



17. Trophi of Sciara thomx L. Dorsal view. 



18. „ cf Hybos femoratus Mull. Lateral view. Only one of the maxillae sb< ws. 



19. „ of Leptis scolopacca L. Dorsal view. 



Feb. 17th, 1904 D 



