Sept. 1896] Skinner: Study of N. American Butterflies. 109 



agos, while dry semi-withered food produces dark imagos of small size. 

 Heat accelerates the pupal stage and cold retards it and the effect is 

 shown in the imagos. The character of the season influences the re- 

 sulting imagos and also the number of broods. Sometimes species 

 which are usually single brooded may in special season become double 

 brooded, and those which are normally double brooded may produce 

 an additional brood. The individuals of these different broods differ 

 and in some cases to such an extent as to have been described as differ- 

 ent species. Nearly, if not all, butterflies produced from wintering 

 chrysalids are different in appearance from the subsequent summer 

 brood or broods. Pieris napi and rapes, are whiter with the blackish 

 markings nearly obsolete. Papilio tiirjuis from wintering chrysalids in 

 this locality look like the Arctic form. Species of Lycczna in their 

 spring dress are very different from those produced later. Even what 

 might be called anatomical differences are produced by season ; thus in 

 some of the Lycsenida; the spring brood is tailless, whilst the summer 

 generation of the same insect is provided with these appendages. 



In passing from the sub-tropical heat of the Rhone Valley through 

 successive zones which are to be met with before reaching the perennial 

 snows of the Corner Grat and the peaks overhanging the Riff el, a col- 

 lection of insects may be made which represents in temperature a dif- 

 ference of latitude as great as from Italy to Scandinavia. I am quite 

 positive that if studies were made from large amounts of material from 

 different localities the observing student would soon learn to tell from 

 whence a given specimen of a species came, from its appearance alone. 

 This is specially true of forms having a wide geographical range. 



In Anthocharis belia by prolongation of the pupal stage we get var. 

 aiisojiia which has the underwings (underside) white with yellowish 

 green blotches, instead of being green with silvery spots. The spring 

 brood of Vanessa atitiopa has whitish wing borders instead of buff. In 

 Holland a pale yellow border, and in Sweden, Norway and Lapland 

 have white borders throughout the year. The same species from Penn- 

 sylvania can be distinguished from California examples, the latter being 

 more nearly related to the European form. Lyccena agestis, a well 

 known little brown butterfly, with a marginal row of rich orange spots, 

 common in the south of England during May and August, when pro- 

 ducing but a single annual brood, appears in July as a variety {artaxer- 

 xes^ that presents the black spots on the wings replaced by white ones, 

 and which was for a long time on that account regarded as a distinct 

 species. 



