ON THE VARIATION OF INSECTS. 3 



dark showed a predominance of the pale red parts, while in those 

 reared in bright daylight the dark blue colour predominated. 

 (Rept. of U. S. Com. Agric, 1884, 309.*) 



b. Metallic coloiirs. 



Ancliocel'is pistacina metall'ica ; near Caterham, Entom. 

 xi. 21, — This remarkable aberration was described as liaving 

 on each fore wing a large patch of metallic cast, thus simulating 

 the condition that is normal with some species of Plusia. 



Colias edusa purpurascens, Entom. xi. 51. — Mr. E. A. Fitch, 

 writing of this species, describes an aberration " beautifully shot 

 with purple or blue," a condition which is quite normal in other 

 species of Rhopalocera, notably some species of Clirysophanus, 



c. The development of green pigment. 



Venilia macidata vlridimacidata, Entom. xi. 103. Lasio- 

 campa qtiercus olivaceofasciata, Entom. xi. 103. — The change 

 of the black markings to olive-green in the Venilia was accom- 

 panied by their partial coalescence. We know that the green 

 pigment in Geometrapapilionaria is first brown, and in Pse?((:?oierj)«rt 

 cytisaria the final change to green frequently does not occur, 

 producing the well-known brownish form of the species. It 

 appears, therefore, probable that the above cases of Venilia and 

 Lasiocampa represent the excessive metabolism of pigments 

 which normally only attain the brown and black stages. 



d. Bleached and albino forms. 



Epinephele tithonus alhidus, Entom. xi. 101. Chrysophanus 

 phlaas schmidtii, Gerh. Ensehia hipunctaria. albida, Entom. 

 xvi. 170. Hepialus humuli, <? , type. — In these cases white 

 takes the place of another colour, and they are in no sense 

 analogous to the white spotless varieties of Abraxas, &c. I am 

 strongly inclined to suppose that the male type of H. humuli had 

 its origin in a variety similar in character to the other three 

 enumerated, and I accordingly class it with them.t 



Ep)inephele ianira hispulla, Hiib., Entom. xi. 1 ; near 

 Dover, &c. E. tithonus pallescens, Entom. xi. 229 ; xvi. 

 234 ; xix. 230. Oporabia dilutata pallescens, Newman, ' Brit. 

 Moths,' 108. Lyccena corydon albicans, H.-S. Melitcea aurinia 

 sibirica, Stgr. Dajiais chrysippiis alcippus, Fab., " al. post. 



* I am inclined to think that this experiment throws light on the reason that 

 the hind wings of Noctuffi, which are under the fore wings, are nearly always pale, 

 while those of Rhopalocera and Geometry are generally concolorous with the 

 fore wings. 



-f In the MoUusca I have shown that albinism, from being excessively rare and 

 aberrational, may become common and even normal, though of course in herma- 

 phrodite species it cannot become peculiar to a sex. Vide " The Variation and 

 Abnormal Development of the MoUusca," in ' Science Gossip,' 1886. 



b2 



