422 ANGIOSPERMAEDICOTYLEDONES 



Schenck records the following Hymenoptera for Nassau. 



(a) Apidae: i. Andrena albicans Mull. ; 2. A. cineraria Z. ; 3. A. combinata 



Chr. ; 4. A. convexiuscula K. ; 5. A. flavipes Pz. ; 6. A. fulva Schr. ; 7. A. gwynana 



K. ; 8. A. nitida Fourcr.; 9. A. parvula K.; 10. A. propinqua Schenck; 11. A. 



tibialis K. ; 12. A. trimmerana K. ; 13. A. varians A"., with the var. helvola L.; 14. 



Bombus hypnorum L. $ ; 15. B. pratorum L. 5; 16. B. terrester Z. 5; 17. Halictus 



albipes Z*. ; 18. H. calceatus Scop. ; 19. Nomada alternata K. ; 20. N. ruficomis L. ; 



N. flava Pz. S; 21. N. succincta Pz. (6) Vespidae: 22. Vespa germanica F. 5, very 



common; 23. V. vulgaris L. $, freq. 



Plateau noticed bees (Andrena sp., Apis, Bombus terrester Z., and Osmia 

 bicornis Z.) and a Muscid (Calliphora vomiteria Z.) in Belgium. 



Hoffer mentions Bombus terrester Z. $ for Steiermark. 



Von Dalla Torre and Schletterer give 2 bees for the Tyrol. 1. Andrena cineraria 

 Z., rare ; 2. A. tibialis K. 



Burkill saw a wasp (Vespa sylvestris Scop., skg.) and a Muscid (Scatophaga 

 stercoraria Z., skg.) on the coast of Yorkshire. 



E. D. Marquard observed the bee Andrena fulva Schr. in Cornwall. 



XXXVI. ORDER CRASSULACEAE DC 



Literature. Knuth, 'Bl. u. Insekt. a. d. nordfr. Ins.,' p. 73. 



In this order the petals serve to attract insects, but some flowers are so small 

 (Tillaea, Bulliarda) that they are only very occasionally visited. In the large-flowered 

 species of Sempervivum and Sedum, on the other hand, self-pollination is often 

 entirely excluded by marked protandry, and insects are absolutely necessary for 

 fertilization. Protogyny is rarer. Nectar is usually secreted by glands at the base 

 of the ovary. In our native species it is only slightly concealed, and most of the 

 flowers must be referred to class EC. In some foreign species, however, it is very 

 deeply situated. 



278. Tillaea Mich. 



992. T. muscosa L. This species bears insignificant reddish or white flowers, 

 solitary in the leaf-axils. They are apparently almost entirely dependent upon 

 automatic self-pollination. 



279. Bulliarda DC. 



993. B. aquatica ( = Tillaea aquatica Z., and T. prostrata Schhthr). According 

 to Ascherson, the minute almost sessile white flowers of this species possess four 

 nectaries, situated between the stamens and the ovary. In my herbarium specimens 

 the pollen-covered anthers almost lie upon the stigmas. 



280. Rhodiola L. 



Flowers dioecious, or sometimes trioecious ; with half-concealed nectar. The 

 hermaphrodite flowers are protandrous. 



994. R. rosea L. (= Sedum Rhodiola Z.). (Ricca, Atti Soc. ital. sc. nat., 

 Milano, xiv, 1871; Schulz, 'Beitrage,' II, p. 188; Warming, Vet. Ak. Overs., 

 Kjobenhavn, 1886-7.) The yellowish-red flowers of this species are dioecious in 



