458 ENTOMOLOGICAL NEWS [Dec., 'l2 



But, what is more, Evylaeus nelumbonis does not get pollen 

 exclusively from flowers of Nymphaeaceae, but it also collects 

 pollen of Sagittaria latifolia. The Nymphaeaceae have been 

 regarded as primitive forms of Monocotyledons and they may 

 be related to the Alismaceae ; but, until this is proved, E. 

 nelumbonis must be regarded as polytropic in the sense here 

 used. 



On page 198 it is stated that in Washington County, Wis- 

 consin, according to Dr. Graenicher, twenty-four of the forty- 

 seven indigenous species of Andrena, sens lat., are oligotropic. 

 That is 51 per cent. At Carlinville, Illinois, after observing 

 595 visits of 51 species, I regard 24 species as oligotropic. 

 That is 47 per cent, and two of the species are doubtful. 

 Of the species named in my list, Flowers & Insects XIX, 

 Bot. Gazette 28:36, 1899, A. nasonii and geranii are not oligo- 

 tropic. Graenicher and I have found the latter collecting 

 pollen of Hydrophyllum virginicum. I have also found it col- 

 lecting pollen of Blcphilia ciliata. 



On page 200 we read "This is certainly a very singular habit 

 on the part of bees, and one which could hardly have been 

 foreseen." On the contrary, it is a phenomenon which finds an 

 analogy in almost every considerable group of living things. 



On page 201 Lovell says : "The oligotropic habit is not bene- 

 ficial to flowers, it concerns the bees alone." On page 202 he 

 says : "All bees including the honey bee show a strong tendency 

 in collecting both nectar and pollen to be constant to one spe- 

 cies of flower. This is manifestly for the advantage of both 

 insects and flowers." 



"The four species of Andrena, which in this locality visit 

 exclusively the willows, do not thus avoid competition nor do 

 they thus benefit other bees" (200). But they avoid compe- 

 tition with related species which collect pollen from entirely 

 different flowers. 



In the Botanical Gazette, 28 :3O, is this statement : "Of 

 thirty-three species whose habits are pretty well known, nine- 

 teen are polytropic and fourteen oligotropic, in the sense in 

 which I use those terms. Four of the oligotropic species get 



