594 TRANS. ST. LOUIS ACAD. SCIENCE. 



ab.; (4) B. ridingsii Cr. § , s. & c.p., one ; (5) B. virginicus Oliv. ^, 

 s., one; (6) Melissbdes bimaculata Lep. (J\ s., one. 



Lepidoptera. — Rhopalocera^ (7) Pieris rapse L., s., one; (8) Pamphila 

 zabulon Bd.-Lec, s., freq. 



Diptera. — Syrpht'dm, (9) Milesia ornata F., f.p., one. 



Gerardia fedicularia* L. — The flowers resemble those of G. 

 Jlava^ as shown on plate ii. of Goodale's ''Wild Flowers." The 

 upper wall of the corolla tube is straight, while the lower is con- 

 cave within. The flowers are synacmic. The style, which lies 

 against the upper wall, curves out over the mouth of the corolla. 

 The stigma runs down each side, where it will easily touch a 

 bee entering on either side. The stigma touches the bee far in 

 advance of the anthers, and cannot receive pollen from them. 

 The anther-cells are tipped below with long awns. The pollen 

 is light and dry, and remains in the cells until a bee touches one 

 of the points, when the chink of the anther gapes and a little 

 pollen is sifted out. If the pressure is continued, all the pollen 

 falls out. The pollen is in this way protected from small bees 

 and flies, and is only discharged when a bee is in position to re- 

 ceive it. The hairs on the anthers and filaments are for the bees 

 to cling to when sifting out the pollen. 



The most abundant visitor, and the one for which the flower 

 is most perfectly adapted, is Bombus atnericanorum. This bee 

 alvt^ays turns head-downwards on entering the flower, and inserts 

 its proboscis into the base of the tube for honey. When it enters 

 the flower, or backs out, the basal joints of its legs strike the tips 

 of the anther-cells, when the pollen falls out. I had often won- 

 dered why this bee turned up-side down to enter the flower, and 

 at first supposed that it was because she wanted to collect pollen 

 at the same time, and turned so as to dislodge it. But I discov- 

 ered that the form of the flower requires it ; for the male, which 

 is almost as frequent a visitor as the females and workers, and 

 only visits the flower for honey, always reverses, which it cer- 

 tainly would not do unless the form of the flower made it neces- 

 sary. The modification which requires the bees to reverse is 

 associated with the peculiar mode of pollen-discharge. 



* See Bailey, Torr, Bull. ii. 39, and Am. Nat. vii. 6S9. On G.Jiava, see Bailey, Am. 

 Nat. xiii. 649, and Young, Torr. Bull. iv. 41. 



