Explanation of Plates. 369 
EXPLANATION OF PLATE XVI. 
Results of Experiments in 1893 upon the colour-relation between 
the larve of Odontopera bidentata and their environment. 
All the figures are of the natural size. 
Fig. 1. Nearly mature larva of O. bidentata showing the effect of 
an environment of black-barked twigs (Quercus cerris). 
This typical example of the results of Experiment I was 
painted by Mr. P. J. Bayzand on July 31st, 1893. All the 
larvee figured on this plate were fed upon the leaves of 
Populus nigra, but they nearly always rested by day on 
the twigs or pieces of bark made use of in the experi- 
ments here illustrated. The larva represented in this 
figure is not in its normal diurnal resting position, having 
been disturbed ; and the same is more or less the case 
with Figs. 3, 5, 7 and 9. 
2. Nearly mature larva showing the effect of an environment 
of weathered pale grey barkless twigs. This typical 
example of the final results of Experiment VII was 
painted on July 28th. A little earlier the larvee had 
been rather paler and resembled more closely the majority 
of the twigs made use of. 
3. Nearly mature larva showing the effect of an environment 
of dark purplish-brown, glossy twigs, probably of birch. 
This typical result of Experiment III was painted on 
July 30th. 
4. Nearly mature larva showing the effect of an environment 
of white-spotted, purplish-brown twigs of birch. This 
typical result of Experiment IV was painted on July 
30th. Although the details of the environment were 
not reproduced, the larva was distinctly less dark than 
that shown in Fig. 3. 
5. Nearly mature larva showing the effect of an environment 
of green leaves and shoots. The food-plant (Populus 
nigra) was employed for this purpose, all dark-barked 
twigs being carefully excluded. A comparison of this 
figure with the others on the same plate indicates that 
the leaves of the food-plant produce no effect when they 
are combined with dark twigs or lichen-covered bark ; 
while a reference to Experiments I to XV shows that 
the great majority of the larvae rest by day upon these 
latter objects in preference to the leaves. This typical 
result of Experiment VIII was painted on July 31st. 
