Seasonal Dimorphism in Butterflies. 191 



variable species, the variation not being due to seasonal 

 causes. This view was published by de Niceville in 

 189-i, and was reiterated by him on several subsequent 

 occasions.* There can be no doubt that de Niceville's 

 opinion receives support from the present series of speci- 

 mens. The fact of C. croealc $ pairing with C. 'pomona ^ 

 tends to show their specific identity, while the simul- 

 taneous occurrence of the two forms in presumably 

 equal numbers seems adverse to the supposition that the 

 dimorphism of this species has a seasonal significance. 



With regard to the first point, that of specific identity, 

 I think there can now be no reasonable doubt that the case 

 is made out. I have already mentioned my own conviction 

 on the matter, which was arrived at independently, and 

 on different grounds. Batchelor's observations here coin- 

 cide with de Niceville's; and it may be added that 

 Piepers,-|- who has bred the species in large numbers, is 

 strongly of the same opinion. On the other hand, Dr. L. 

 Martin, writing of the butterflies of Sumatra (Journ. 

 Asiat. Soc. of Bengal, LXIV, ii, p. 490, 1895), considers 

 C. crocale and C. catilla {po7nona) distinct, on the following 

 grounds : — C. crocale, the far commoner form, occurs on 

 roads, near houses and gardens, and is never found in the 

 forest. C. catilla is found only in the forest. The antennae 

 of C. crocale are black in both sexes, those of C. catilla are 

 red. The underside of the males in C. crocale is unspotted, 

 and the tuft of hair on the inner margin is whitisli. In 

 C. catilla the males, like the females, have reddish spots 

 on the underside of both wings, and the tuft of hair is 



Dudgeon on the same occasion (August 12) as those mentioned 

 above. They are stated to have i'ormed part of a migratory fliglit 

 which lasted all day. 



* Gazetteer of Sikkim, p. 166, 1894 ; Journ. Asiat. Soc. Bengal, 

 LXIV, ii, p. 490, 1895 ; Journ. Bombay Nat. Hist. Soc, xi, p. 586, 

 1898; Journ. Asiat. Soc. Bengal, LXVIII, ii, p. 211, 1899. The 

 tirst two of these are cited by Mr. Trimen, loc. cit., p. Ixxvi, note. 



t " Die Farbenevolution bei den Pieriden," Tijdschr. der Neder- 

 landsche Dierk. Vereenig. ; (2) Deel V, p. 119, 1898. Piepers gives 

 thaurmna, Keak., as a synonym ; tlie latter, however (from Mada- 

 gascar), is unquestionably distinct. " Pomona, Cram." (ibid.) is a 

 .slip ; the name was bestowed by Fabricius. Piepers's view was first 

 published in 1891 — "Observations sur des vols de Lepidoptferes " — 

 Natuuikundig Tijdschrift voor Ned.-Indie, Dl. L, 1891, pp. 205, 

 222. In the same periodical, Dl. LVII, 1898, he repeats it, but 

 speaks, rather curiously, of " Onnnia, Feld.," as a form of " Catopsilid, 

 pomona. Cram." {loc. cAt., p. 111). 



