200 Miscellaneous. 



that the predaceous fishes might confound it with the sea-weed, and 

 therefore not exterminate it"*. — Proc. Acad. Nat. Sci. Philad. 

 Nov. 5, 1889, p. 341. 



On Seasonal Dimorphism in Japanese Butterflies. 

 By Dr. Adolf Fritze. 



Besides the nine Butterflies cited by Pryer f as seasonally di- 

 morphous in Japan, namely Papilio machaon, L., P. xuthus, L., 

 P. macilentus, Janson, Pieris napi, L., Colias Jtj/ale, L., Terias 

 multiformis, Pryer, Vanessa G-album, L., V. C-aweum, L., and 

 Polyomntatm phlceas, L., two new ones occur, according to my 

 investigations in the interior of central Japan in the summer of 1889, 

 namely Thecla arata, Brem., and Vanessa levana, L. 



Thecla arata, Brem., which has hitherto been regarded as single- 

 brooded, has two generations which are markedly seasonally di- 

 morphous, and this seasonal dimorphism shows itself especially upon 

 the underside, while the upperside of both generations is uniformly 

 blue ; only the blue of the summer form is darker than that of the 

 winter form. In the latter the ground-colour of the underside is 

 dark greyish green, interrupted by three white bands of different 

 breadth, to which are added on the hind wings several smaller 

 white streaks. The lower angle of the hind wings is orange-red, 

 with four black spots, the two upper ones having a bluish-white 

 nucleus. It is this generation that Pryer has figured. It flies in 

 May and June. 



The summer generation, which flies in August, shows on the 

 underside exactly the pattern of the spring generation, but instead 

 of the greyish-green coloration we have here a dark brown, and in 

 place of the white bands and streaks we find light brown ones ; 

 the orange-red of the angle of the hind wings is much less iutense, 

 and the bluish- white nuclei in the black spots disappear entirely or 

 almost entirely. 



Vanessa levana, L. — The seasonal dimorphism of the European 

 form of this species has long been known ; it occurs also in the 

 Japanese form, although here other and very remarkable characters 

 occur. Thus, while the summer generation, the so-called prorsa 

 form, which flies in August, is exactly like the German form, the 

 German spring generation, the levana form, is entirely wanting in 

 central Japan. In its place appears a prorima form, which has a 

 rather close resemblance to the form figured by Weismann in his 

 ' Studien zur Descendenztheorie ' pi. i. fig. 2. Prom this the 

 Japanese prorima is distinguished chiefly by the greater prominence 

 of the black spots and bands, by several brown spots at the root of 

 the fore wings, and by a straight light brown transverse baud upon 

 the hind wings. This generation flies in May and June, and has 

 hitherto been regarded as a distinct species, Vanessa burcjana, 

 Brem. — Zool. Anzeiger, January 13, 1890, p. 12. 



* Peter Osbeck, Reise nach Ostindien und China. Aus dem schwed- 

 ischen iibersetzt von J. G. Georgi ; Rostock, 1765, p. 400. 



t Pryer, ' Rhopalucera Niponica. — A description of the Butterflies of 

 Japan,' Jokohama, 1886 and 1888. 



