LIST OF ILLUSTRATIONS. 



In all the figures of flowers, unless otherwise specified, the letters 

 refer to the same parts, viz. : — pistil, / — style, /' — stigma, st— 

 stamen, y^— filament, /'—anther, a — petals, pe — corolla, co — 

 sepals, s. — calyx, ca — ovary, o — ^honeygland, h — pollen, /o. 



Geranium sylvaticum . . I 



1. Stigma of the Alder (after Axell) . 9 



2. Stigma of the Hop >. >, • 9 



3. Stigma of the Wheat , . , , 9 



4. Stigma of the Willow , , , > • 9 



5. Stigma of the Flax ,> ,, 9 



6. Stigma of Nuphar ,> ,. 9 



7. Seciion oi Plantago viajor ,, ,, . 10 



8. Section oi Plumbago Europca ,, ,, . 10 



9. Section of Poterium sanguisorba ,, ,, . 10 



10. Section of Sanguisorba officinalis ,, ,, . . . 10 



11. Mouth-parts of a Wasp 13 



12. Front part of head of Prosopis, seen from below, with the 



mouth-parts extended (after Miiller) .... 14 



13. Prosopis (after F. Smith) . ... 14 



14. Mouth-parts of Polistes (after Miiller) . 14 



15. Mouth-parts of Andrena, seen from below ,, ,, . . 15 



16. Mouth-parts of Halictus ,, ,, ■ IS 



17. Mouth-parts of Panurgus ,, ,, . IS 



18. Mouth-parts of Halictoides ,, ,, IS 



19. Mouth-parts of Chelostoma ,, ,, • IS 



20. Head of Humble-bee (Bombus agrorum), with the mouth- 



parts extended (after Miiller) .... 16 



21. Left hind-leg of Prosopis ,, ,, . . . -17 



22. Left hind-leg of Sphecodes ,, ,, '7 



23. Sphecodes (after Westwood) .... -I? 



