128 Lord Walsingham on Asiatic Tovtricidae. 



Brussa, VI. 2 Siberia 2 . Corea — Gensan, VI. 1886 

 {Leech). Japan z — Hondo— Q\ wake, VI. 1885, VI.-VII. 

 1887 (Pryer). 



The specimens of this species from Corea and Japan differ 

 from our English form in their larger size and paler colouring 

 on the underside, but precisely correspond in their markings. 

 The males all have a small hanging appendage near the base 

 of the limbus in the hind wings, a character hitherto confined 

 to the genera Exartema, Clem., and Cymolomia, Ld. The 

 discovery of this character in Japanese specimens caused me 

 to re-examine carefully a series of British specimens of 

 arcuella, which has been placed by different European authors 

 in PentJiina, Tr., and Ser icon's, Tr. It was at once apparent 

 that all the males in the series possessed a very small rudi- 

 mentary appendage, scarcely noticeable unless special atten- 

 tion had been called to it. The stronger development of this 

 character in Japanese specimens is scarcely sufficient to justify 

 their description as a distinct species, especially as I find 

 German specimens of intermediate size and decidedly paler 

 on the underside than our British examples. 



Meyrick, whose attention had been called to the existence 

 of the lobe, wrote (HB. Br. Lp. 465) that this was so rudi- 

 mentary that it appeared insufficient for generic separation. 

 In this I am unable to agree with him, for it is certainly a 

 structural character, corresponding with that which was relied 

 upon by Clemens when describing the genus Exartema. 



The question is one of degree, but it may fairly be argued 

 that the possession of a structural character rather than the 

 mere degree of its development is the true test of generic 

 rank; and Meyrick has recognized this principle very forcibly 

 in including Ptycholoma, Stph., and Lozotcenia, Stph., in the 

 genus Cacoecia, Hb., the only cause of separation by the 

 older authors having apparently been the inferior development 

 of the costal fold. 



If Meyrick is justified in placing arcuella in the same 

 genus as many other species which possess no limbal fold or 

 lobe, it follows that the Japanese form (specially inseparable, 

 as I think, from arcuella) would fall into a different genus 

 through the slightly greater development of the limbal lobe, 

 unless he is prepared to include with it Exartema, Eccopsis, &c. 



Clemens, in describing Exartema, clearly refers to the 

 hind margin being deeply and sharply excised opposite to the 

 median nervules. Pie described five species : the first two 

 only, viz. nitidana and permundana, possess this character ; 

 the other three species, versicolor ana, inornatana, and fascia- 

 tana, have the dorsum evenly rounded beyond the flexus, 



