993 



almost liomogeneoiis dark blotch. In front next to the apex, this blotci> 

 is sharply cnt off from the above mentioned anterior triangular spot 

 by an oblique light-hued line, the lastnamed spot moreover often 

 showing a very light shade itself. 



Now directing our attention especially to the points of corre- 

 spondence between the various components of this wing-pattern, and 

 on the contrary less heeding the differences, we are easily led to 

 the conclusion that it is composed of seven transverse rows of dark 

 spots, separated by lighter bars. 



The external of these transverse rows (1) must then be looked 

 for in the above-mentioned dark blotch along the external margin. 



The second (11) is the complete row of nine spots, with its set of 

 accompanying fainter bars. 



The third (111) forms the external border of the dark central field. 



The fourth (IV) is the dark line along the outer side of the 

 discoidal mark, which although somewhat obliquely, may be said 

 to run across the middle of the central area fi'om fore- to hind- 

 margin. 



The fifth (V) is the inner front-line of the central field, this line 

 being sometimes double. 



The sixth (VI) the single, curved series of spots over the middle 

 of the proximal light wing-area. 



The seventh (VII) is formed by the faint traces of spots near the 

 wing-root. 



The light intervals between these seven bars may be indicated as 

 in former j)ublicalions by the letters A to G. In those intervals 

 some traces of still other dark bars, varying in distinctness, are 

 again met with; so it is not improbable that originally the stronger 

 transverse bands everywhere alternated witli less dark and sharply 

 marked rows of spots. 



In all these featiiies the pattern of populi remarkably agrees with 

 that of Arctiïds, as I described it in a former paper, and in the 

 same way with that of numerous other families of Lepidoptera, as 

 I hope to show afterwards '). 



') Here i wish already to mention tlial Annette F. Braun. in a paper : Evolution 

 of the Color Pattern in the Micro! epidopterous genus Lithocolletis (Journal of the 

 Academy of Nat. Sc. of Philadelphia XV 2f> Ser. 1914) as tlie result of an onto- 

 genetic and phylogenetic investigation about the colour-development on the forewings 

 of these Tineids, gives as her opinion that all patterns of this polymorphic genus 

 may be derived from seven dark transverse bars, forming to her mind a primary pattern, 

 on which a secondary one, composed of still darker line-^, will later on be so to 

 say projected, as is also proved by the development inside the pupal sheath. 



