W. H. Pattern on the Genus Macropis. 287 



vulgaris, was led to believe that the bees pierced the cellular 

 tissue of the flowers with the ligula for the juices with which 

 to moisten the pollen. This act of the bee seems to me both 

 impossible and unnecessary. The ligula is too weak ; and if 

 we are to look to the Lysimachia for a solution of the problem, 

 it is well to ask whether the glands with which the filaments 

 and base of the corolla are beset may not furnish the nectar. 

 In the American L. ciliata, L. qiiadrifblia, and L. stricta, 

 and on the filaments at least of the European L. vulgaris the 

 glands are very numerous. But upon the flowers of stricta 

 and quadrifolia the Macropis has not yet been found, although 

 the flowers have been often watched ; it seems, therefore, that 

 the glands afford no attraction. We must conclude that it is 

 with nectar that the pollen is moistened ; and as it has been 

 my good fortune to distinctly observe a female Macropis 

 sucking nectar from the flowers of Rhus glabra, it is evidently 

 from these and other flowers that the Macropis obtains the 

 honey for the food both of itself and its young. 



But why does the Macropis moisten the pollen as it is col- 

 lected? this is an unusual habit. The social bees moisten 

 it in order that it may be retained on the pollen plates. The 

 Scopulipede and Gastrilege bees retain the dry pollen with 

 the hairs forming the pollen-brushes. The Lysimachia pollen 

 is not of so dry a nature that hairs would not hold it. An 

 altogether new interest was given to the genus Macropis by 

 Hermann Muller's observation that it alone of all the solitary 

 bees of Germany moistened the pollen as collected, thus econo- 

 mizing the expanse of hairs upon the legs*. The retain- 

 ing-hairs upon the posterior legs of Macropis are unusually 

 short. By moistening the pollen they are enabled to retain 

 much larger masses than they otherwise could. Such, also, 

 is the habit, as I have observed, of the allied American 

 genera Scrapter, Calliopsis, and Perdita (P. S-7naculata, Say) ; 

 and Fritz Muller has recorded the same habit for Centris, 

 Teirapedia, and Epicharis in Brazil f, although in these latter 

 genera the scopa is long. 



On account of the close resemblance which Macropis bears 

 to the higher bees, Shuckard (' British Bees ') was led to be- 

 lieve that it would be found to agree with them in their noisy 



* L. c. p. 47, and Anw. d. Darw. Lehre auf Bienen, p. 22 (1872). 



t ' Nature,' vol. x. p. 103. These observations by Fritz Muller are 

 open to doubt. In Centris, as in our native genera Diadasia (n. g.) and 

 Melissodes, the hairs of the scopa are conspicuously plumose, and the 

 pollen would have a matted appearance even when dry. It can be stated 

 with confidence that, even if the pollen is slightly moistened by these 

 bees, it is not formed into a paste, as it is by the social bees. 



20* 



