Exjplanation of Plates. 373 



overspread with grey mentioned on October 16tli. The 

 greyish appearance does not come out in the figure, the 

 effect being merely to render the brown of a paler tint. 

 The larva was painted on October I7th. 

 Fig. 13. Larva at the same period and exposed to the same envi- 

 ronments as that shown in Fig. 10. The description of 

 Fig. 11 applies in every respect, except that the larva 

 here represented was a specially dark example, and was 

 painted on October 16th. 



14. Larva, nearly mature in the last stage, showing the effect 



of an environment of black-barked twigs up to the 

 beginning of hybernation. During and after hybernation 

 the larva was placed (I, B) in an environment of lichen- 

 covered sticks, but, as the figure indicates, it had ceased 

 to be susceptible to such influences, and no eft'ect was 

 produced. Before hybernation it had lieen one of the 

 five darkest larvaj. The painting was made on May 19th. 



15. Larva at the same period and exposed to the same environ- 



ments (I, B) both before and after hybernation as that 

 shown in Fig. 14. Although conspicuous white patches 

 appeared on this and other larva? subsequent to hyber- 

 nation, it is improbable that this efiect was due to the 

 lichen which formed the surroundings after the begin- 

 ning of hybernation. The comparison of the whole 

 of the larvc-B indicates that they had then ceased to be 

 susceptible to the colours of the environment. The 

 larva was painted on May 22nd. 



Explanation of Plate XVIII. 



Results of Experiments in 1893-4 upon the colour-relation between 

 the larvaj of Gastfopacha qnercifolia and their environment. 



All the figures are of the natural size, and all represent the 

 natural resting position. 



All the figures represent the larva? in the last stage, and all but 

 one nearly mature, in May 1894. 



Fig. 1. Larva of Gastropacha qnercifolia, nearly mature in the last 

 stage, showing the effect of an environment of lichen- 

 covered sticks up to the beginning of hybernation. 

 The lichen employed was probably Ramalina farinaeea. 

 During and after hybernation the larva was placed in an 

 environment of Idack-barked twigs (IL G) which, it is. 



