Final Remarls. 53 



half the continent, as T have previously shown, Init extends to 

 the Pacific coast and is found as far south as San Diego, showing 

 over tliis wide range absoUitely no diiferences that would justify 

 varietal designation. All the characters are al)Solutely the same, 

 and the rather dark coloring of the horny and chitinous i)arts of 

 the body in the California, Dakota, and Colorado specimens 

 would indicate that the western forms have this peculiarity as 

 compared with the eastern. This species is now known to pol- 

 linize all the true Yuccas so far studied, and accompanies them 

 across the continent. It thus poUinizes Yacca filamentosa and its 

 several forms in the northeast; }'. r/loriosa and Y. aloifolia in the 

 southeast ; Y. nngnstifoUa (glaucn) in the Rocky Mountain re- 

 gions; Y. rupicold and Y. ehita in the southwest ; and Y. baccata, 

 which connects the territory of Y. aagustifolin with that of Y. 

 hrevifolia and Y. whipplei. It thus occurs in the same territory 

 as its two congeners, Pronuba synlhelica and P. maculata^ with its 

 alerrima variety, while these last are restricted to their respect- 

 ive Yuccas. This fact, as Professor Trelease has pointed out, 

 strengthens the inference that brevi.foUa and whipplei are primary 

 Pacific coast types, while baccata is an immigrant from the east. 

 It remains yet to observe the pollinizers associated with Yacca 

 filifera, Y. airstralis, Y. trecideana, and Y. gualeinalensis, each of 

 whicli will prol)ably have a distinct Pronuba, while the other 

 Yuccas not enumerated here will prol)al)ly not have distinct 

 species connected with them. 



It would carry me too fav to s])eculate further on the addi- 

 tional facts brought forth, luit I would urge in conclusion that in 

 all ]Mr. Trelease's interesting observations in his special studies 

 of these different species of Yucca, and after having paid par- 

 ticular attention to the point, he has failed to see a single 

 Pronuba in any species attempt to feed on either the stigmatic 

 secretion or the septal nectar. He was also unable to con- 

 vince himself that in any case the insect malces use of the 

 tongue in pollination, as he once thought it might. In this and 

 other respects he fully confirms the conclusions which I have 

 (h-awn in my previous communication to the Society, while the 

 additional data which I have indicated give further force to my 

 remarks ui)on variation, as exemplified l)y these Prodoxids. 



