ON THE VARIATION OF INSECTS. 99 



melanism ; but Mr. H, Goss (Entom. xi. 7:3), in describing a 

 (\i\vk variety of Chelonia villica from Brighton, mentions that 

 seveial dozen larvfe from the same place produced the type, and 

 suggests further that the aberration was due to a diseased condi- 

 tion in the larva. Now this variety exhibited coalescence of the 

 dark markings and suppression of the light ones, which further, 

 was more complete on the right than on the left side, so it seems 

 certain that it had nothing in relation with such cases of 

 melanism as Pieris napi hryonue. I am therefore inclined to 

 separate all dark forms into two groups: 1. True melanisms. 

 2. Cases of coalescence of markings due to disease. What the 

 precise nature of the disease may be, and which forms precisely 

 are to be classed in either group, is for future investigations to 

 decide. 



n. Coalescence of dark markings. 



Argynnis bellona fasciata. The zigzag band fused with the 

 oiitward of the inner markings, forming a wide band (Maynard). 

 Chrysophanus hypoijlilaias fanciatus, Strecker. C. piilceas fasciatus, 

 Entom. xi. 25, with fig. (W. P. Weston). Acronycta tridens 

 fasciata, with marginal band, Entom. xi. 24. — In these cases 

 the dark markings have coalesced to form bands, such as are 

 normal with other species, and it is hard to consider them 

 entirely as cases of disease. Whatever may be their nature, 

 I think there can be no doubt that they point to the way in which 

 bands were originally acquired in banded species, and very 

 possibly by careful breeding from banded aberrations such as 

 these, a two banded race might be formed. 



Argynnis lathonia valdensis, Esp. A. idalia. ]Maynard figures 

 a variety in which tlie silver spots on underside are partly 

 coalesced. — These two examples of coalescence of the silvery 

 markings in Argynnis may be considered here. The.y probably 

 do not essentially differ from the other cases of coalescence 

 cited above. Silvery markings have, however, probably originated 

 in a metamorphosis of some white pigment, in which case 

 AntJtocharis belia ausonia, Hb., will be an instance of reversion. 



o. Suppression of dark markings. 



Nathalis iole Irene, Fitch. Lycrena astrarche deleta, ground 

 colour of underside pearly white, with the red marginal spots 

 very bright, but nearly all the normal black spots absent. Entom. 

 xii. 185, with tig. L. icarus icarinus, And L. bellargus cinnus, are 

 also cases of suppression of markings. L. icarus $• nigromacidata 

 (Entom. 1887, 210) is an opposite condition. Melitcea cinxia 

 paucimaculata, Newman, Brit. Butt. p. 43. Pieris rapce iminacu- 

 lata, tom. cit. p. IfU. Loniaspilis marginata subdeleta, Newman, 

 Brit. Moths, p. 101. Abraxas grossulariata deleta, tom. cit. 99; 



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