408 Transactions of the Society. 



some length in a paper published in the Journal of this Society,* 

 but will supplement those observations by a few general rules, 

 that will, I hope, enable the student to glean facts from his 

 preparations. 



1. When the mandibles and maxillae are present the insect is 

 a blood-sucker, as Culcx, Tabanus, or Simnlmm. 



2. When the labium is without teeth and has only a simple 

 arrangement of tracheos, and the mouth is armed with maxillae and 

 with maxillary palpi, the insect is predaceous, as in Empis. 



3. When the labium is without teeth, but has well developed 

 tracheal, and the mouth is armed with maxillae and with maxillary 

 palpi, the insect feeds on the pollen of flowers, as in Syrphus. 



4. When the labium is without teeth, or maxilhe, and the palpi 

 present (well developed) are labial, the insect feeds on the juices 

 or the smaller pollen of flowers, as in Trypeta, or Pipunculus. 



N.B. — The palpus is labial when unattached to the stipes or 

 cardo of the maxilla — in Calliphora labial, in Syrphus or Culex 

 maxillary. 



5. When the mouth-parts are as in Rule 4, except that the 

 labella or paraglossae of the labium have strongly chitinised teeth 



* " The Mouth-parts of the Nemocera and their Relation to the other Families 

 in Diptera," January 1904. 



EXPLANATION OF PLATE VII. 



Fig. 14. — Part of the abdomen of Conops quadrifasciata Deg. 6 . This and 

 the next two figures are drawn from pinned specimens to show the ordinary 

 appearance as seen when examined with a simple lens. 



Fig. 15. — Part of the abdomen of C. quadrifasciata 9 to show the curious 

 unpaired organ that is appended to this part in the female. 



Fig. 16. — Part of the abdomen of C. flavipes L. 9 , to show an even more 

 remarkable development of the appended lobe. 



Fig. 17. — Part of the abdomen of C. flavipes L. 9 , drawn from a prepared 

 specimen, to show the complicated spinose armature of the part. 



Fig. 18. — Trophi of Norrellia spinimana Fin. 9 . (The mouth does not differ 

 in the sexes.) Raptorial type, to illustrate Rule 5. This insect is placed in the 

 Cordyluridse, and a lateral view is given of the trophi. 



Fig. 19. — The teeth of N. spinimana drawn from a higher magnification. 

 They are very strong and highly chitinised, and may be compared with those on 

 the paraglossae (labella) of the blow-fly (Calliphora erythrocephala Mg.). 



Fig. 20. — Trophi of Lyperosa (?) 9 . This is a Sinhalese insect, and is, though 

 much smaller, closely allied to our blood-sucking Stomoxys, the chief point of 

 difference being the larger relative size of the palpi in Lyperosa ; the male arma- 

 ture does not differ from that of the female. Blood-sucking Muscid type, to 

 illustrate Rule 8. Lateral view. 



Fig. 21. — Part of the paraglossae of Hydrotea occulta Mg. 6 , highly magnified, 

 to show the situation and character of the teeth characteristic of the general 

 feeder. Armature identical in both sexes. To illustrate Rule 6. This insect 

 belongs to the Anthomyia family, and the preparation shows the dorsal side upper- 

 most. 



Fig. 22. — Trophi of Tabanus sudeticus Zlr. 9 . The males are without the 

 mandibles. A blood-sucker of the most pronounced type. To illustrate Rule 1. 

 Dorsal view. 



