56 



Castniadae. Besides Yuccrte, Felder describes and figures a 

 Mexican species in the Wiener Ent. Monatsschrift. In the 

 long abdomen, the segments distinct, and head "parts, are 

 resemblances to the Moths. 



In my earliest papers (1865) on the Hawk Moths, I 

 have spoken of the dimorphism of the caterpillars, Deilepliila, 

 Pldegetlwutins, and then of the ampelophagic genera, showing 

 that they possessed indifferently, without regard to sex, a 

 green or brown tint. I called these tints "cosmical", the 

 brown being like that of the earth and the green like the 

 vegetation. In this view they are protective. Several 

 green larvae in the Hawk Moths become brownish during 

 the last twenty four hours, while wandering over the soil 

 before pupation. This change in color takes place even in 

 confinement over a white surface. The origin of this dimor- 

 phism offers an inviting study ; it occurs in many Moths and 

 some Butterflies. In my writings I have maintained the 

 following theses. That the lepidopterous fauna of the summit 

 of the White Mountains (Oeneis, Laria, Pachtwbia etc.) is 

 a relic of the Glacial Epoch. That our fauna has three 

 proximate sources, boreal (E), austral (S) and indigenous 

 during tertiary times (N). That certain forms such as 

 Scoliopteryx and Dipteryyia have remained unaltered since the 

 separation of the European and American faunae by the 

 Ice Period, while others, as Catocala rcJicta, Copimaniestra 

 oceiilciita, have become distinct species. Intermediate are 

 those species which differ only in one stage, and that mostly 

 the larval, such as Apatela ocddentalis from A. psi. I have 

 shown the method of variation, in its expression in the perfect 

 insects; the retention, occasionally, in specimens of relicta 

 of blue scales on the band proves the reversion to the Euro- 

 pean fraxhu. I have further shown that, in genera of Southern 

 extraction, the area of successful hibernation is more restricted 

 than that of the summer flight and breeding of the Moth, as 

 in Alctia aryiltacea, the Cotton worm. 



My theory (Detroit Meeting, Am. Ass. Aug., 1875) that 

 the Butterfly fauna of the summit of Mount Washington is 

 a survival from the Glacial Epoch, equally with the theory 



