3 THE ENTOMOLOGIST. 



Soc, 1B8G, 59; and " xanthic forms," torn. ciL, 08. Arctia 

 villica angelica, B., vide Staudinger CatL— In these examples 

 yellow takes the place of white. No evidence is forthcoming as 

 to the precise conditions under which this occurs, except that 

 the yellow varieties of Pieris rapes are said to be much more 

 frequent in America than in Europe, and therefore probably the 

 result of a different climate from that to which the species has 

 always been accustomed in Europe, its native country. Much 

 light, however, is thrown upon the probable nature of the change 

 by the observation of Mr. Coverdale, repeated by numerous 

 subsequent observers, that the white pigment of several species 

 of Lepidoptera may be changed to yellow by the application of a 

 caustic alkali. 



Abraxas grossulariata lutea, Entom. xx. 278, is probably due 

 to an extension of the normal yellow markings. 



Arctia villica fulminans, Stgr. ; locality, Syria. — This is the 

 only instance I have of the change of the yellow pigment into 

 red, and in this case there is always some indication of red 

 about the typical form. The opposite case, that of a red pigment 

 changing to yellow, is, as I have shown in a previous paper, by . 

 no means uncommon ; nor is it confined to insects, being also 

 witnessed in birds (Fringillidse), mollusca (Tellinidse), &c. Two 

 other cases of change of colour may be mentioned here, as 

 requiring further investigation, — Ino statices mannii, Ld., and 

 Noctua suhrosca, suhccerulea, Stgr., the last, from Livonia and 

 Finland, being rather a geographical race. An extraordinary 

 variety of Arge galathea is also on record (Entom. xvi. 210), in 

 which reddish and greenish take the place of black and white. 



The above varieties differ notably from suffused, melanic, 

 and other forms, in that they have their origin in a change in the 

 nature of a pigment equally prominent in the type form, and not 

 in the excessive development of an unaltered colour, as is the 

 case with the following. 



Hepialus Immuli suhrosea, 3-, Ent. Mo. Mag., 1881, 111. — 

 Mr. Barrett, in describing this form, says the apical- third of the 

 silvery white fore wings was distinctly tinged with a delicate pink 

 (an extension of the pink of the apical cilia), which fades after 

 death. This pink colour is evidently what Dr. Hagen (Ent. Mo. 

 Mag., 1872, 78-83) described as hypodermal, the colours of this 

 class being mostly bright and light, and fading after death of the 

 insect. These hypodermal colours are supposed by Hagen to be 

 produced by a photographic process, while the darker or some- 

 times metallic epidermal colours are due to a process of oxidation, 

 and never fade after death. 



It is strangely contradictory of this theory, however, that Mr. 

 P. K. Uhier found by experiment that in specimens of the 

 Heteropteron Murgantia histrionica, Hahn., those reared in the 



