JOURNAL OF VARIATION. 



Vol. IX. No. 11. November 15th, 1897. 



On the scales of European Zygaenides {Illustrated by Plate). 



By E. W. WAKE BOWELL. 



By the kindness of Mr. Tutt, I have recently been enabled to 

 make microscopic preparations of a fairly representative series of 

 Em'opean Zj/r/aenidae. The subject has proved of greater interest 

 than I should have surmised, owing to the fact that this family 

 presents us with examples of a regularly ascending series of scale 

 forms, from the simple oval to the more complicated forms found 

 usually in highly developed species. The scales, further, seem to afford 

 a means of discriminating between closely allied species. It must be 

 understood that the remarks concerning descent which follow are 

 based solely upon the characters of the scales ; not that I propose to 

 found any classification upon what is probably only a secondary 

 character, but the conclusions arrived at from a study of the scales 

 may probably be confirmed by more general reasoning, and even if 

 not, the comparison may be interesting. The family includes the 

 genera Ino, Aijlanpe, and Zijgaena. In Ino, the scales are generally 

 small, scantily distributed and rarely bifid. As usual, the scales of 

 the lower wings are less highly specialised than those of the upper. 

 Ino cJdoros seems the simplest, both upper and lower wing scales 

 being plain, " strap-shaped." 1. tennicornu, I. prnni and /. chri/- 

 sorejihala form a middle group, with the scales of the lower wings, 

 simple, of the upper, bifid. /. budensia is a curious form, having the 

 lower scales exceedingly small, whilst the upper ones have their ends 

 decorated with a number of small points (r/c, the ends of the 

 columns separated by the striae). This is visible in the other species, 

 though to a much smaller extent. It appears to be a kind of 

 degeneration, for the divided ends of other Zygaenid scales are 

 composed of groups of columns, not of separate individuals. 

 /. ampelophaga is the most highly developed of the species which I 

 have observed (lower bifid, upper trifid, occasionally even quadrifid). 

 This would appear to be a case of parallel development to that which 

 obtains in Ziifiaena ; and on a smaller scale we note that /. tenuicornis 

 seems to bear the same relation to /. j^nini that Z. trifolii does to 

 Z, lonicerae. 



In Aglaope all the scales are strap-shaped, very long, and with 

 parallel sides. Similar scales are to be found in some of the genus 

 Ino, and they may especially be compared with those of /. cldoros, 

 which, although unlike them in many respects, retain the character of 



