28o ANGIOSPERMAE—DICOTYLEDONES 



it does not return when the pressure is removed. According to Darwin, automatic 

 self-pollination readily takes place, but is far less productive than cross-pollination. 



Visitors. — Darwin in England, MacLeod in Flanders, Hermann Miiller in 

 Westphalia, and myself in Schleswig-Holstein have observed the honey-bee. Hermann 

 Miiller remarks in this connexion : — ' It is characteristic of the honey-bee that it 

 does not disdain even this flower's tiny store of honey. The whole inflorescence 

 is pulled down by the weight of the bee, which then sucks the flower's head down- 

 wards. It visits a few flowers, at most four, on one inflorescence, and then flies away 

 to another plant of the same species. Xenogamy is thus eifected to a great extent.' 



While as a rule the honey-bee has been observed as the chief pollinator, 

 Burkill (Proc. Phil. Soc, Cambridge, viii, 1894, names a hover-fly (Plaiycheirus 

 manicaius) as the most active visitor at Scarborough, a short-tongued bee {Halictus 

 morio) and a Muscid [Scaiophaga) at Cambridge. He gives the following list for 

 Scarborough (June, 1893) and Cambridge (July and August, 1893). — 



A. Coleoptera. 1. Anthobium torquatum Marsh.; 2. Ceutorhynchidius floralis 

 Payk. ; 3. Mehgethes aeneus F. B. Diptera. {a) Anihomyidae : 4. Anthomyia sp.; 

 5. Caricea tigrina F.; 6. Chortophila cinerella FaH.; 7. C. sepitorum Meade; 

 8. C. sp. ; 9. Homalomyia armata il/^. ; 10. Hydrotea irritans /^a//. ; 11. Hylemyia 

 puUula Zett.; 12. Pogonomyia alpicola i?«rf. ? {U) Bibionidae: 13. Scatopse brevi- 

 comis Mg. (c) Chironomidae : 14. Chironomus sp. {d) Chloropidae: 15, 16, 17. 

 Three sp. of Chlorops; 18. Oscinis sp..?, very freq. (e) Empidae: 19. Empis 

 punctata F. (_/") Muscidae : 20, 21. Two undetermined sp. (g) Sarcophagidae : 

 22. Sarcophaga sp., very freq. (A) Scaiophagidae : 23. Scatophaga stercoraria L. 

 (;■) Sepsidae : 24. Hydrellia griseola i^a//. ; 25. Sepsis cynipsea L. {k) Syrphidae: 

 26. Paragus tibialis Fall.; 27. PipizeUa virens F.; 28. Platycheirus albimanus i^. ; 

 29. P. manicatus Mg.; 30. P. scutatus Mg.; 31. Syrphus balteatus Z>^^. ; 32. S. 

 corollae F.; 33. Syritta pipiens L. (/) Tabanidae: 34. Ptiolina crassicornis Pz. 

 (rti) Pachinidae: 35. Myobia inanis /a//. ; 36. Siphona cristata i^. ; 37. S. genicu- 

 lata Deg. C. Hemiptera. 38. Aphis sp. ; 39. Siphonophora artemisiae Koch. D. 

 Hymenoptera. Apidae -. 40. Andrena parvula A'. 5 ; 41. Apis mellifica L. 5 , rare ; 

 42. Bombus hortorumZ.; 43. Halictus minutissimus A'. J ; 44. H. morio Z'. 6 and 5, 

 not infrequent ; 45-50. Six undetermined species. E. Lepidoptera. {a) Nociui- 

 dae: 51. Hadena fasciuncula Haw. (b) Pyralidae: 52. Crambus pratellus L. 

 (c) Tineidae: 53. Porrectaria sp. (d) Tortricidae : 54, 55. Sp. of Tortrix ? F. 

 Neuroptera. 56. Thrips sp. 



Sickmann mentions the fossorial wasp Gorytes lunatus Dahlb., infrequent. 



Besides the honey-bee, Herm. Miiller observed the following. — 



A. Hymenoptera. Apidae: i. Andrena convexiuscula K. 5, skg. ; 2. A. 

 xanthura K. 5, po-cltg. ; 3. Bombus agrorum F. 5 and 5> skg. (Strassburg); 4. 

 Halictus flavipes /". 5, po-cltg. B. Diptera. Conopidae: 5. Myopa buccata Z., 

 skg.; 6. M. testacea Z., do. C. Lepidoptera. Rhopaloccra: 7. Thecla rubi 

 Z. $, skg. 



Miiller further records three Lepidoptera, skg., for the Alps (' Alpenblumen,' 

 p. 248). 



MacLeod, in addition to Apis, observed Halictus sp. in Flanders (Bot. Jaarb. 

 Dodonaea, Ghent, vi, 1894, p. 338). H. de Vries observed Bombus terrester Z. § 

 in the Netherlands (Ned. Kruidk. Arch., Nijmegen, 2. ser., 2. deel, 1875). 



673. M. arabica All. — Kirchner ('Flora v. Stuttgart,' p. 484) states that 

 the flower mechanism of this South European species agrees with that of M. sativa. 



