146 Cincinnati Society of Natural History. 



usual perspicuity, aucl leaves one in doubt whether it is meant to say 

 that all Ilyponomeutd are very variable, or only that Spunctella is so. 

 Either way I must dissent from the statement. The species of Hyi^o- 

 nomeuta are not verj' variable in the number, and certainly not in the 

 position of the spots. The Colorado species (if it is a Hyponomeuta) 

 is an exceptional case. Some variability no doubt exists, as it does in 

 almost all species (alwaj^sin deference to Prof. Riley, excepting P. yuc- 

 casella). But when we consider the great number and small size of 

 the spots in Hyponomeuta, the wonder is that there is not more varia- 

 tion, especially as to the position and size of the spots. In England 

 three allied species of the genus are found feeding on the same plant 

 {euonymus), yet there is no difficulty in distinguishing them. On the 

 other hand, F. yuccasella is a single species of a somewhat anomalous 

 genus, and notwithstanding the light which has been shed upon it b^^ 

 Mr. Riley, " dark lanthoru," much no doubt 3-et remains to be chroni- 

 cled by " other observers." and I should much sooner expect a wide 

 range of variation in such an extraordinary creature, than in any spe- 

 cies of the well known Hyponomeuta. 



But let us return to our alleged (by Mr, Rile}') 5punctella. We 

 have seen where and under what circumstances it was found. How 

 came it there? Its presence in such nuiyihers, and under all the circum- 

 stances, these could not have been accidental. No doubt one frequent- 

 ly meets with a single specimen, or with a few specimens of a species at 

 a considerable distance from any known food plant of the species; but 

 then such specimens are as likely to be found in one place as in anoth- 

 er; and are not found in great numbers, and only in the flowers of a 

 single plant, and in company with a species which so closel}- resembles 

 them; and, besides, such cases are sporadic, not epidemics as in the 

 case we are discussing. The presence of such numbers of the supposed 

 Hyponomeuta, five to one more numerous than P. yuccasella itself, in a 

 particular localit}', in the flowers of yucca, in company with the so-close- 

 ly-resembling Pronuba, and in the absence of every other species, and 

 at such a distance from every kind of vegetation upon which allied 

 species of Hyponomeuta feed, either in the larvse state, or as imago, in 

 the absence too of all evidence that it feeds in any of its states upon 

 yucca flowers, and even occupying the same position in repose in the 

 flowers that the true Pronuba does, calls for some explanation diflerent 

 from that which might be satisfactory, if it Avas an instance of the 

 chance happening of one or of a few specimens under ordinary circum- 

 stances. So also the total absence of the species in all of its states 

 from the wooded region, when by every analogy drawn from the his- 

 tory of kin(b'ed species, it might be expected to occur, and the absence 

 . of all evidence that its food plants and habits as to footl difler trom 



