Extracted from the Proceedings of the Entomological 

 Society of London of December 7th, 1898, 



Dr. DixEY exhibited a series of Pierid butterflies from the 

 Neotropical region to show the existence among them of 

 seasonal forms. The species shown were Parura rurina, 

 Fold., c? ; P- neocypris, Hlibn., $ ; Phcebis argante, Fabr., 

 (?, 9 ; P. agarithe, Boisd., ^ ; Callidryas sennce, Linn., 

 (?, $ ; C. philea, Linn., S. In each case three specimens 

 were shown, exemplifying the "wet season," "dry season," 

 and " intermediate " forms of the species. These had been 

 selected from the Hope Collection by permission of Professor 

 Poulton. 



"With reference to the exhibit. Dr. Dixey remarked that 

 although direct evidence as to .the seasonal changes in these 

 Neotropical species was at present scanty, the indirect evidence 

 was strong ; inasmuch as the range of variation here shown 

 was analogous with that existing in certain African and 

 Oriental species, whose seasonal relations had been put on a 

 firm basis by the work of Watson, Barker, Marshall, and 

 others. In every one of the present instances the " wet 

 season " form tended to be more deeply coloured, and to have 

 its markings on the underside more fully developed ; while 

 the " dry season " form was usually smaller, had its forewings 

 more sharply pointed, and was nearly or entirely devoid of 

 markings on the underside. He stated further that where 

 evidence of the date of capture existed, it accorded very fairly 

 with the supposition that these variations bore relation to 

 seasonal conditions, though of course more data of this kind 

 were much needed. He had selected the specimens of each 

 species so far as possible from the same locality, endeavouring 

 thus to meet the possible objection that these varieties, several 

 of which had been described as distinct species, might have a 

 local rather than a seasonal significance. He added that by 

 an " intermediate " form he meant simply one that came 

 somewhere between the other two — not necessarily half-way. 

 He was accustomed to use the term in a general sense as 

 equivalent to the German " Zwischenform," not as conveying 

 the idea of an arithmetical mean (Mittelform). 



The President observed that the exhibit was of special 

 interest, as affording the first recorded evidence of the exist- 

 ence of seasonal dimorphism in Neotropical butterflies. 



