286 ANGIOSPERMAEDICOTYLEDONES 



however, pressure is exerted on the carina alone or the alae alone several times 

 in succession, these parts resume their original position again, but slowly, and the 

 mechanism gives distinct indications of exhaustion. By the union of various co- 

 operating (synergic) organs, Nature has not only afforded greater certainty of 

 movement, but has even been able to minimize exhaustion. 



The movements of the higher animals are similarly rendered effective by the 

 grouping of co-ordinated muscles : in this way the same advantages are obtained as 

 by the co-operation of alae, carina, and vexillum in the flower of Trifolium repens. 



According to Darwin's experiments (' Cross- and Self-fertlsn.,' p. 361) cross- 

 pollination is necessary for the complete fertility of white clover; when insects are 

 excluded the flowers are to a great extent self-sterile. 



Visitors. Hermann Miiller in Westphalia (H. M.), Buddeberg (Budd.) in 

 Nassau, and myself (Kn.) in Schleswig-Holstein (S.-H.), Riigen (R.), Helgoland (H.), 

 and Thuringia (T.) have observed the following. 



A. Diptera. (a) Conopidae: 1. Myopa buccata Z., skg. (H. M.); 2. M. 

 testacea Z., do. (H. M.). () Syrphidae: 3. Eristalis sp. (H. M.) ; 4. Volucella bom- 

 bylans Z., skg. (H. M.). B. Hymenoptera. Apidae : 5. Andrena fulvicrus K. 5 , 

 skg. (H. M.) ; 6. A. nigriceps K. ?, do. (H. M.); 7. A. sp. (Kn., H.) ; 8. Antho- 

 phora quadrimaculata Pz. $ (Kn., S.-H. and H.) ; 9. Apis mellifica Z. 5, very freq., 

 skg., and po-cltg. (H. M. ; Kn., S.-H. and R.); 10. Bombus cognatus Steph. ^ and 5 

 (Kn., S.-H.); 11. B. derhamellus K. (Kn., S.-H.); 12. B. lapidarius Z. $ and j (Kn., 

 S.-H. and T.); 13. B. pratorum Z. , skg. (H. M.); 14. B. rajellus K. 5, do. 

 (Kn., R.); 15. B. terrester Z. (Kn., T.); 16. Cilissa leporina Ps. t, skg. (Budd.); 

 17. Colletes balteatus Nyl. (Kn., S.-H.); 18. Eucera difficilis (Duf.) Per. (Kn., R.) ; 

 19. Halictus maculatus Sm. 5, po-cltg. (H. M.); 20. H. sexnotatus K. $, skg. (H.M.) ; 

 21. H. smeathmanellus K. 5, do. (Budd.); 22. H. tarsatus Schenck 5, do. (H. M.); 

 23. H. zonulus Sm. 5, do. (H. M.); 24. Megachile willughbiella K. t> (H. M.) ; 

 25. Psithyrus quadricolor Lep. J, skg. (H. M.). C. Lepidoptera. Rhopalocera : 26. 

 Coenonympha pamphilus Z., skg. (H. M., T.); 27. Epinephele janira Z., skg. (Kn., 

 S.-H.); 28. Hesperia, do. (H. M.); 29. Melitaea athalia Esp., do. (H. M.,T.); 

 30. Lycaena semiargus Rott., do. (Kn., S.-H.); 31. Pieris brassicae Z., do. (H. M. ; 

 Kn., S.-H.) ; 32. P. napi Z., do. (H. M.). 



Herm. Miiller also noticed 11 bees, a hover-fly, and 10 Lepidoptera in the Alps 

 (' Alpenblumen,' p. 244). 



Von Dalla Torre saw the bee Stelis aterrima Pz. $ in the Tyrol. 



Hoffer records the rare Alpine humble-bee Bombus alpinus Z., an old nest- 

 female, for Steiermark. Loew observed Halictus zonulus Sm. $, po-cltg. in the 

 same province (' Beitrage,' p. 53), and the honey-bee in Silesia (op. cit., p. 34). 



Schiner saw the Muscid Ocyptera pusilla Mg. (probably vainly endeavouring 

 to suck) in Austria. Rossler noticed the butterfly Colias hyale Z. as a useless visitor 

 at Wiesbaden. Schenck records the bee Melitta leporina Pz. for Nassau. 



Schletterer mentions the following bees for the Tyrol (T.) and Pola. 



1. Andrena dubita Schenck; 2. Megachile muraria Z. ; 3. Osmia tridentata 

 Duf. et Perr.\ 4. Stelis aterrima Pz. (T.). 



Friese, on the authority of Konow, gives the two following rare bees for 

 Mecklenburg. 



1. Colletes nasutus Sm. ; 2. Meliturgus clavicornis Ltr. 



Alfken and Hoppner (H.) observed the following bees at Bremen. 





