9. Fore-leg of Platychirus albimanus, ♂ 10. Fore-leg of Platychirus clypeatus, ♂ 11. Platychirus, ♂ and ♀, quadrate spotting 12. Melanostoma mellinum, ♀ triangular spotting 13. Larva of Microdon 14. Wing of Helomyza pallida 15 & 16. Diagram of a fly's leg. _Vide_ C, I, on page 91. 15. As viewed from behind 16. As viewed, horizontal section (through A-B) 4 (_b.f._) base of femur (_t.f._) tip of femur (_b.t._) base of tibia (_t.t._) tip of tibia (1) upper or outer side (2) under or inner side (3) hinder side (4) fore side (5) upper fore side (6) upper hind side (7) under hind side (8) under fore side 17 & 18. Base of wing, illustrating the difference in O, 6^1 respectively in 17. Urophora 18. Trypeta 19. Profile of Drosophila 20. Profile of Ceratomyza denticornis 21. Profile of Tichomyza fusca 22. Antennæ of Notophila cinerea; note the "thorn" on second joint 23. Antennæ of Hydrellia griseola 24. Antennæ of Tichomyza fusca 25. Profile of Hydrellia griseola 26. Profile of Ochthera mantis 27. Wing of Borborus equinus 28. Wing of Limosina sylvatica 29. Section of a collector's net, showing 4 (_a_) the small end of a large net; (_b_) a detachable muslin bag; (_c_) elastic closing the bag; (_d_) transparent celluloid end 30. A small bag, closed and detached 31. Box for carrying bags [Illustration: PLATE VII. (APPENDIX).] NUMBERED LIST OF FAMILIES, _Together with references to the Analytical Table and Notes._ The sequence of the numbering indicates some proximity of relationship, in most cases at least, in respect of some particulars. Nos. Refs. FAMILIES—Notes I —. PULICIDÆ: fleas regarded as flies with atrophied or undeveloped wings. About 30 native species. II 3. CECIDOMYIDÆ: mostly gall-gnats, minute and midge-like, or very frail, slender and gnat-like. _Cecidomyia destructor_ is the notorious Hessian-fly, injurious to cereal crops. III 10. MYCETOPHILIDÆ: fungus-gnats; 34 genera; many common species. The marvellous "army-worm," the larvæ of _Sciara militaris_, which (being not a feeder on fungi) may be classified either separately or as belonging to this family, has been observed travelling in Continental forests in millions, described as massed together with a viscous mucus in bands said to be as large as 5 or 6 inches wide, 1 inch deep, and 50 or more feet long! IV 11. BIBIONIDÆ: 40 species of small and medium sizes; commonly the males are black, but the females of some species coloured; _Bibio marci_, of a largish size, pubescent, and black, sometimes appears in great numbers on fine spring days, as likewise do some smaller black species of the same genus; ocelli absent; semi-blind. V 13. SIMULIDÆ: midge-like flies, mostly with wings, limbs, and bodies of short length; the largest, _Simulium reptans_, only 2-3 mm., is common; its larvæ are aquatic. Some foreign species are called sand-flies and are much dreaded poisonous blood-suckers.