RANUNCULACEAE 43 



elsewhere, while Hermann Muller noticed it in Westphalia. He also saw but much 

 more rarely the field humble-bee (Bombus agrorum F. 5) sucking nectar in the 

 legitimate way, and effecting crossing. This bee, however, in order to enable its 

 somewhat shorter (12-17 mm.) proboscis to reach the nectar, must have thrust 

 its head right into the opening of the spur, so as to diminish the distance to be 

 traversed by about 5 mm. Bees with a still shorter proboscis are excluded from 

 legitimate enjoyment of the nectar, and they must bite through the spur to get at it. 

 Bombus terrester Z. the proboscis of which is only 7-3 mm. long is particularly 

 addicted to biting through the bend of spur and stealing nectar through the 

 hole. Hermann Muller saw one of these bees settle upon the upper side of a 

 columbine flower, lick the bases of the sepals, and on finding nothing there, creep 

 to the lower surface and thrust its head into the spur. Still finding nothing, it once 

 more crept to the upper surface, again vainly licked the bases of the sepals, and 

 finally bit through the spur, thrust the tip of its proboscis into the hole, and thus 

 secured the nectar. It subsequently robbed the remaining spurs of the same flower, 

 and those of other flowers, without further deliberation, and it is probable that 

 every member of the species has to learn by experiment how to get at the nectar. 

 But, after having acquired the knowledge, it perforates the spurs even of unopened 

 flowers, thus stealing a march on legitimate visitors, as H. Muller observed at 

 Lippstadt, and I myself at Kiel. Sprengel noticed that the honey-bee (with a 

 proboscis 6-7 mm. long) behaved in the same way as B. terrester. Hermann Muller 

 confirms this, and adds that it also often uses the perforations made by B. terrester. 

 The holes bitten out by humble-bees when stealing nectar were also observed by 

 Schulz in the Tyrol and in Thuringia. 



Both honey-bees and some of their smaller allies among which Hermann Muller 

 noted Halictus smeathmanellus K. 5 and H. leucozonius Schr. 5 collect pollen upon 

 columbine flowers, and in doing so may effect either cross- or self-pollination. 



Visitors. Schenck observed the following in Nassau. 



Hymenoptera. (a) Apidae: 1. Andrena convexiuscula K. ; 2. A. curvungula 

 Thorns. ; 3. Halictus xanthopus K. (5) Vespidae : 4. Odynerus melanocephalus Z. 



MacLeod noticed three humble-bees in the Pyrenees, of which only Bombus 

 hortorum Z. was skg. legitimately (' Pyreneenbl.,' p. 386). 



91. A. atrata Koch. (Herm. Muller, ' Alpenblumen,' p. 137.) The flowers 

 essentially agree with those of the last species. It is, however, doubtful whether 

 automatic self-pollination occurs should insect-visits fail. 



Visitors. Herm. Muller observed three humble-bees, and two bees (species of 

 Andrena). 



92. A. pyrenaica DC. (MacLeod, ' Pyreneenbl.,' pp. 385-6.) The flowers 

 are darker than those of A. vulgaris, with which they agree in other respects. The 

 narrow spur of the petals is 20 mm. long, but 5-6 mm. broad at the entrance, so 

 that a proboscis about 15 mm. long is able to reach to the tip. 



Visitors. MacLeod observed none. 



93. A. chrysantha A. Gray. (Knuth, ' Bloemenbiol. Bijdragen.') This 

 species is indigenous to North America, and is a garden plant in West Europe. It 

 possesses flowers agreeing essentially with those of A. vulgaris, but the spur is 



