370 ExplaTiation of Plates. 



Fi(i. 6. About half-grown larva showing the effect of an environ- 

 ment of bark covered with, bluish-green lichen, probably 

 Phiiscia pulverulenta. Tliis typical result of Experiment 

 XIII was painted on August 1st. 



7. About half-grown larva showing the effect of the environ- 



ment last described. This second typical example of the 

 results of Experiment XIII was painted on August 3rd. 



8. Xearly mature larva showing the effect of an environment 



of bark covered with orange lichen, perhaps Physcia 

 parietina, probably combined with P.2}ulvervlenta. This 

 typical result of Experiment XIV was painted on 

 August 4th. 



9. Xearly mature larva showing the effect of the environment 



last described. This second typical example of the 

 results of Experiment XIV was painted on August 5th. 



10. Xearly mature larva showing the effect of an environment 



of lichen-covered sticks. The lichen was probably 

 Ramo.llna faruuicea. This typical result of Experiment 

 XV was painted on August 10th. 



11. Xearly mature larva showing the effect of the environment 



described in Fig. 6. This tliird typical example of the 

 results of Experiment XIII was painted on August 31st. 



Comparing the last six figures of larv* together with the repre- 

 sentation of the various forms of lichen-covered bark employed in 

 the experiments, it is seen that there was no special resemblance to 

 the characteristic features which distinguished one form of environ- 

 ment from the others. Thus the orange colour of the lichen did not 

 produce any corresponding effect upon the larvae shown in Figs. 8 

 and 9. 



The whole results prove that hideutata is a larva with remarkable 

 susceptibility to the colour of its environment. In this respect it 

 is equal to the most sensitive of all larvse hitherto tested — Amphi- 

 dasis betularia. The latter is more susceptible to green leaves and 

 shoots, becoming bright green when restricted to their influence. 

 When exposed to lichen-covered bark, however, hidenta.ta was shown, 

 in Experiments XII to XV, to be far more sensitive. 



EXPLAXATION OF PlATE XVII. 



Results of Experiments in 1893-4 upon the colom'-relation between 

 the larvae of Gastropacha quercifolia and their environment. 



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

 normal resting position, except that the larvae more frequently rest 



