PROTECTIVE RESEMBLANCES IN LEPIDOPTERA 37 



rib by two narrow stalks. The larva, in eating, 

 leaves several pieces of leaf attached to the mid-rib by 

 one or two stalks, which, therefore, present a very 

 similar appearance to that of the larva itself. The 

 concealment which is thus effected is sufficiently 

 indicated in fig. 10. 



An appearance of leaf-like flatness conveyed by 

 arrangement of colour 



Another very interesting example, in which the 

 effect of shadow is gained by arrangement of colour, 

 is afforded by the chrysalis of the Purple Emperor 

 Butterfly (Apatura iris). The large green pupa re- 

 sembles a leaf in the most perfect manner, mid-rib 

 and oblique veining being represented. I showed a 

 small twig of sallow, to which a pupa was suspended, 

 to several friends, but it was almost invariably over- 

 looked ; even when it was pointed out, the observer 

 frequently failed to see any difference between it and 

 a sallow leaf. The most extraordinary thing about 

 this resemblance is the impression of leaf-like flatness 

 conveyed by a chrysalis, which is in reality very far 

 from flat. In its thickest part the pupa is 8'5 mm. 

 across, and it is in all parts very many times thicker 

 than a leaf. The dorsal side of the pupa forms a 

 very thin sharp ridge for part of its length, but the 

 slope is much more pronounced in other parts and 

 along the whole ventral side. But exactly in these 



