LIST OF ILLUSTRATIONS. 



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

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

 stamen, /filament, /'anther, a petals, /* corolla, co 

 sepals, s. calyx, ca ovary, o honeygland, h pollen, po. 



K1Q. PAGE 



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- Section of Plantago major ,, ,, . . . 10 



8. Section of Plumbago Europea ,, ,, . . .10 



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



10. Section of Sanguisorbn officinalis ,, ,, . . . 10 



11. Mouth-parts of a Wasp 16 



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



mouth-parts extended (after Miiller) . . . .17 



13. Prosopis (after F. Smith) 17 



14. Mouth-parts of Polistes (after Miiller) . 17 



15. Mouth-parts of Andrena, seen from below ,, ,, . . 18 



16. Mouth-parts of Halictus ,, ,, . . 18 



17. Mouth-parts of Panurgus ,, ,, - 18 



1 8. Mouth-parts of Halictoides ,, ,, 18 



19. Mouth-parts of Chelostoma ,, ,, ' 18 



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



parts extended (after Miiller) 1 9 



21. Left hind-leg of Prosopis ,, ,, 2O 



22. Left hind-leg of Sphecodes . . . . 2O 



23. Sphecodes (after Westwood) . . . .20 



