584 TRAXS. ST. LOUIS ACAD. SCIEXXE. 



The quotation which Henslow makes from Miiller* is in re- 

 gard to V. nigrum and reads as follows: "The short tube wi- 

 dens out into a flat, five-lobed limb, which takes up an almost 

 vertical position : the inferior lobe is the longest, and the two su- 

 perior are shorter than the lateral lobes, so that an insect settles 

 most conveniently upon the inferior. The stamens project al- 

 most horizontally," etc. From the relative positions of the limb 

 and stamens, one would expect insects to prefer the latter as a 

 resting-place. For some time MiJller supposed V. nigrtim con- 

 tained no honey, but he afterwards found it. Of the visitors 

 vt hich he observed, 3 came for honey, 6 for pollen, and i for both 

 honey and pollen ; so that most of them were after pollen, and 

 would most probably alight directly upon the stamens. Of 6 vis- 

 itors of V. phceiiiciutn^ 5 were in search of pollen, and 1 vainly 

 sought for nectar. Of 10 visitors of V. Thafsus^ 7 were after pol- 

 len, and 3 "semeed to be sucking." Of 15 guests observed by 

 me on V. Thapsus^ all visited the flower exclusively for pollen, 

 and invariably settled upon the stamens. 



There seems, therefore, to be no reason for supposing, as Hens- 

 low does, that Verbascum is in the first stage of irregularity, and 

 that insects use the lower lobes of the corolla as a landing-place. 

 By exposing its stamens, the flower has changed from nototribe 

 to sternoiribe, from dusting its visitors upon their backs to dust- 

 ing them upon the ventral surface. In this connection it may be 

 well to mention that Delpinof has pointed out that Verbascum 

 is adapted to pollen-collecting bees, and that the hairs upon the 

 stamens are for the bees to cling to when gathering pollen. 



The following visitors were observed on 6 days, between June 

 27 and July 9 : 



Hymenoptera. — Apt'dm (i) Apis mellifica L. ^ , ; (2) Bombus ameri- 

 canorum P^. § . Atidrenidte, (3) Agapostemon nigricornis F. 2 ? (4) 

 Augochlora lucidula Sm. 9 i (s) Halictus pectoralis Sm. 9 (6) H. cori- 

 aceus Sm. $ ; (7) H. conlusus Sm. 5 : (S) H. cressonii Rob. $ — 

 all c.p. 



Diptera. — Syrphidic, (jgi) Pipiza pistica Will. ; (10) Syrphus atnerica- 

 ««s Wied. ; (11) Allograpta obliqua Say; (12) Mesograpta marginata 

 Say; (13) M. geminata Say ; (14) Syritta pipiens L. — all t'.p. A7ithomy- 

 idce, (15) Anthomyia sp., f.p. 



* Fertilization of Flowers, 429. f Ulterior! osservazioni. 



