94 THE ENTOMOLOGIST'S RECORD. 



took type-like specimens at 5,500 ft. ; but 5,000 ft. in the Bernese 

 Oberland is equivalent to an altitude of 6,000 ft. in Eastern Switzerland. 



This apparently impossible state of things is, however, quite easily 

 explained if we assume all these interesting forms to be aberrations of 

 bryoniae. If a certain combination of meteorological influences, direct 

 and indirect, tend to produce, aberrationally, a form of bryoniae 

 approximating to the lowland race ; it is only to be expected that such 

 a line of variation should attain its greatest development at the lower 

 levels, although transitional forms occur at any altitude where bryoniae 

 exists. 



Mr. Williams actually bred such transitional specimens from eggs 

 laid by bryoniae ; and he especially notes that all the £ s he observed 

 in the locality where he captured the ? were very heavily and darkly 

 marked. further, it is most probable that the extreme white type- 

 like aberrations are the offspring of some of the transitional forms. 

 Another question now must be considered. How can one reconcile the 

 fact, that two of my extreme white 2 s have the underside of napi t 

 and so resemble that race almost exactly, and the certainty that other 

 such specimens will occur in the future, with the theory that they are 

 aberrations of bryoniae ? This question is no real difficulty : as noted 

 before, the underside of bryoniae is very variable, and among the 5 s, 

 specimens with a very similar underside to spring napi occur occasion- 

 ally ; the two specimens under consideration therefore, are most 

 probably only the outcome of a simultaneous development of two forms 

 of variation common to bryoniae. 



When specimens of bryoniae are occasionally taken in the 

 lowlands of Central Europe and in Ireland, it is not suggested that 

 they are hybrids, for the simple reason that it is obviously impossible ; 

 yet in reality it is probably just as impossible that the war- 

 like specimens of the Alps are hybrids either. One more proposi- 

 tion can be brought forward, namely, that the extreme white 

 aberrations are napi, and the transitional ones aberrations of bryoniae. 

 If this were so, then the first eight specimens of my series would be 

 called napi and the others bryoniae. But of the first eight, those with 

 the underside approaching bryoniae would have to be regarded as 

 aberrations tending towards bryoniae, or as hybrids. The latter has 

 already been considered, but if we assume the former, then it is but so 

 slight a step to the ninth specimen of my series tnat it would have to be 

 considered an aberration of napi too. And if so, why not the tenth 

 and all the others ? That would include those specimens taken at 

 6,500 ft. which is obviously impossible. Conversely if the transitional 

 specimens of high altitudes are to be taken as aberrations of bryoniae, 

 then so must the same forms from lower levels, and so on until we get 

 to the five specimens we started from ; and if they are bryoniae it is 

 certainly more logical to conclude the two type-like specimens to be a 

 further development of the same form, than to call them napi, and 

 assume that that race exists in certain Alpine regions, but can only 

 produce one or two specimens in each locality each season. That 

 latter conclusion may, I think, at once be called impossible. Indeed 

 it is difficult to see tbat any sufficient argument can exist for maintain- 

 ing that napi could ever establish itself in the bryoniae zone ; for if it 

 could do so, it implies that the conditions necessary to the white race 

 of 2 exist in certain Alpine regions, in which case bryoniae would 



