564 ANGIOSPERMAEDICOTYLEDONES 



The stamens are curved inwards in the bud, but when the floret opens they 

 extend one after the other, and their anthers dehisce, while the style has so far 

 attained to scarcely half its length. When the anthers have withered, the style 

 elongates to its full length, and the stigma becomes receptive. Automatic self- 

 pollination is consequently impossible. 



Besides stocks bearing hermaphrodite florets, there are also somewhat smaller 

 female ones. Such florets possess stamens reduced to a greatly varying extent, 

 and they are not infrequently double. In some localities female stocks are rare; 

 elsewhere they are commoner; Magnus says they number about 10% at Homburg, 

 while Schulz states that they may even reach about 30 % at Brunswick and Halle. 

 Turner (Nature, London, xl, 1889) says the florets are trimorphous. Warnstorf 

 (Verh. bot. Ver., Berlin, xxxviii, 1896) describes the pollen-grains as very large, 

 white, spherical, adherent owing to the presence of short spinose tubercles, up to 

 93 fj, in diameter. 



Visitors. Herm. Muller (H. M.) and myself (Kn.) observed the following in 

 North and Central Germany. 



A. Coleoptera. Chrysomelidae: 1. Cryptocephalus sericeus Z., gnawing the 

 florets (H. M.). B. Diptera. (a) Bombyliidae : 2. Exoprosopa capucina F., freq. 

 in July (H. M.). (b) Empidae : 3. Empis livida Z., very numerous, skg. (H. M.). 

 (c) Muscidae : 4. Lucilia species (H. M.) ; 5. L. cornicina F. (H. M.). (d) Syrphidae 

 6. Eristalis arbustorum Z., freq., skg. and po-dvg. (Kn., H. M.) ; 7. E. intricarius Z 

 (H. M.) ; 8. E. nemorum Z., freq., skg. and po-dvg. (H. M.) ; 9. E. tenax Z., do, 

 (Kn., H. M.); 10. Helophilus pendulus Z., do. (Kn., H. M.); n. Rhingia rostrata 

 Z., skg. (Kn., H. M.); 12. Syrpnus balteatus JDeg., po-dvg. (Kn.); 13. S. pyrastri Z. 

 skg. and po-dvg. (H. M.); 14. S. ribesii Z., do. (Kn.); 15. Volucella plumata Mg. 

 skg. (H. M.). C. Hymenoptera. Apidae: 16. Andrena cetii Schr. 5, po-dvg 

 (H. M.) ; 17. A. convexiuscula K. $ (H. M.) ; 18. Apis mellifica Z. , freq., skg. and 

 po-dvg. (H. M., Kn.); 19. Bombus agrorum F. 5 and $, very common, skg. (H. M.) 

 20. B. lapidarius Z. 5 and J, do. (Kn., H. M.); 21. B. muscorum F. 5 and $, do 

 (H. M.); 22. B. pratorum Z., do. (H. M.); 23. B. sylvarum Z. 5, $ and $, do 

 (H. M.); 24. B. terrester Z. $ and $, do. (H. M.); 25. Halictus cylindricus F. & 

 in large numbers (H. M.) ; 26. H. leucozonius Schr. $, do. (H. M.); 27. H 

 rubicundus Chr. 5, po-cltg. (H. M.) ; 28. H. zonulus Sm. % skg. (H. M.); 29 

 Psithyrus rupestris Z. $, do. (H. M.) ; 30. P. vestalis Fourcr. $ and $, do. (H. M.) 

 D. Lepidoptera. (a) Pyrahdae: 31. Botys purpuralis Z., skg. (H. M.). (b) Noc- 

 iuidae : 32. Plusia gamma Z., freq., skg. (Kn., H. M.). (c) Rhopalocera : 33. Epinephele 

 janira Z., skg. (Kn., H. M.) ; 34. Pieris brassicae Z., do. (Kn.) ; 35. P. rapae Z., 

 numerous, skg. (Kn., H. M.) ; 36. Polyommatus phlaeas Z., do. (H. M.). (</) Sphingidae : 

 37. Zygaena filipendulae Z., very common, skg. (Kn.). 



Alfken and Hoppner (H.) record the following for Bremen. 



A. Hymenoptera. Apidae'. 1. Andrena marginata F. 5 and S; 2. Bombus 



agrorum F. 5, 5 and J; 3. B. arenicola Ths. 5, 5 and ; 4. B. derhamellus K. 



%, ^ an d &> s ^g' *> 5- ^- hortorum Z., var. nigricans, Schmiedekn. 5 ; 6. B. jonellus K. 



^ and S ; 7. B. lapidarius Z. 5, 5 and $ ; 8. B. terrester Z. 5 and % ; 9. B. lucorum Z. 



$ ; 10. B. proteus Gerst. 5, 5 and $ ; 1 1. B. muscorum F. 5, J and 5 ; 1 2. B. sylvarum 



Z. 5 and t; 13. B. variabilis Schmiedekn. $>, 5 and 5; 14. Halictus calceatus Scop. 



5 and S ; 15. H. leucopus K. 5 and S; 16. H. leucozonius K. $; 17. H. rubicundus 



Chr. $; 18. H. zonulus Sm. $ and S; 19. Psithyrus barbutellus K. 5 and S; 



20. P. campestris Pz. $ and $ ; 21. P. rupestris F. 5 and J ; 22. P. vestalis Fourcr. 



$ and S. B. Diptera. Syrphidae: 23. Arctophila mussitans F. 5 and $, very 



common, skg. (H.) ; 24. Eristalis tenax Z. 



