On Pronxba YaccdsellK. 



]53 



tohasis (jigantella, with its long, narrow wings, and strong flight) 

 seemed to' support the h^^xithesis, yet the testimony of the Tineina 

 generally was against it, though ''the T/nettia as a family is not well 

 adapted either to the proof or disproof of it." The entire known 

 species of Tineina of Colorado formed my premise — not P. yuccusella^ 

 Rilej', alone; and I submit that the premise is not invalidated b}^ what 

 Prof. Riley has written about P. yvccasella. "But," Trof. R. writes, "the 



Colorado specimens (of P. yuccasella) are above the average size, 

 which is natural, since the capsules of Yuccn augustifolia^ in which 

 the Colorado specimens breed, are larger than in other species, etc." 

 Just as natural, no doubt, as it is tor white Tineina to be atti'acted to 

 white flowers. Is the size of an insect to be measured by the size of 

 its food plant? Is a codling moth from a liig apple naturally larger 

 than one from a small apple? Nobody denies that a deficient supply 

 of food may tend to dwarf an insect, or a man, but is the supply in the 

 capsule of any species of yucca small enough to dwarf the moth ? 

 Beside, Pi-of. Riley's explanation of the alleged slightly-greater 



average size of the Colorado specimens — that it depends on the greater 

 size of the seed capsules — does not in an}- wa}' support the hjqDothesis 

 (of Baird and Packard) alluded to, which has nothing to do with sup. 

 ply of food, in which respect western species certainly have no advan- 

 tage over eastern ones, but is based upon supposed metereological and 

 climatic causes; and Prof. Riley's language that " the Colorado speci- 

 mens are, if anything a little larger," does not allow much for the in- 



