Seasonal Dimorpliism in Bidtcr flics. 197 



intermediate, and T. ccelcstis the dry-season phase of the 

 species ; but they are none of them confined to seasons, 

 but occur (as is tlie case with other species in very arid 

 countries) as mere coexistent variations." * Of T. 'proto- 

 media, Klug, he remarks, " At Aden all three [seasonal] 

 types occur together as mere variations." f Other species 

 oi Te7^acolics oi which similar statements are made are T. 

 protradus, Butl, T. j'hisadia, Godt., T. piiellaris, Butl., T. 

 vestalis, Butl., T. evagorc, Klug, and T. plcione, Klug. 

 With regard to Terias Butler also notes that, "as in 

 Teracolus, those countries which have no wet season never- 

 theless produce the three phases of a species as coexistent 

 varieties." \ There is reason to think that in the New 

 World, at any rate, there may occur a similar intermingliug 

 of forms which is not confined to " countries having no wet 

 season." Thus, Messrs. Godman and Salvin write as 

 follows : " Many of these forms [of Terias'\ are said to be 

 due to the season of the year at whicli they appear, wet- 

 season and dry-season broods having each their peculiar 

 characteristics. These observations have been made chiefly 

 in the east. In our country we have not noticed any 

 phenomenon of this kind." § Mr. G. C. Champion again, 

 if my memory does not deceive me, in the discussion that 

 followed the exhibition of certain specimens of Callidnjas 

 referred to by Mr. Trimen (J,oc. cit.), many of which were 

 collected by himself, stated that according to his experience 

 of these butterflies, the varying forms of the same species 

 from the same locality had no definite relation to the 

 seasons. Colonel Swinhoe, besides recording the fact that 

 he has taken all the seasonal forms of certain eastern 

 Teracoli flying simultaneously at Karachi, has also averred 

 that he has captured Byhlia simplex, Butl., the supposed 

 dry-season form in India of B. iUthyia, Drury, practically 

 all the year round. Some doubt has been thrown by de 

 Niceville and by Marshall on the latter observation ; the 



* Ann. Mag. Nat. Hist., 1897, vol. ii, p. 502. The dates of Col. 

 Yerbury's captures at Aden clearly prove the simultaneous occurrence 

 of different " seasonal " forms, l^ut they do not seem incompatible 

 with a certain amount of correspondence on the part of these phases 

 with tlie time of year. See, e. (/., the dates given for Teracolus 

 ccelpstis and T. acaste ; Proc. ZooL Soc, 188i, pp. 489, 490. 



f Ann. Mag. Nat. Hist,, 1897, vol. ii, p. 507. 



i Ibid., 1898, vol. i, p. 57. 



§ Biologia Centrali- Americana. Rliopal. ii, p. 154. 



