in their Natural attitudes of Rest. 485 



markings are seen to be rendered vertical by the attitude, 

 as in the moths represented in Figs. 1 and 2, 



Among the moths which are usually found at rest upon 

 rocks or stone walls the species of tlie genus Bryo^^hila are 

 probably the best known. The well-known B. 2yerla, Fabr., 

 is so common everywhere throughout the country that 

 very little need be said of it. The range of variation in 

 this moth is not very great, although in a few districts it 

 tends to resemble some local peculiarity in the prevailing 

 tints of the walls upon which it both feeds as a larva and 

 rests as an imago. A typical example is shown in Fig. 4, 

 upon an old, lichen-covered, stone wall. The peculiar grey 

 lichen-like markings of its fore-wings are seen to blend 

 almost perfectly with the surface upon which the moth is 

 resting, B. muralis, Forst. = glandi/cra, Hlibn., is a species 

 chiefly confined to our southern coasts and presents an 

 interesting contrast to B. pcrla in its great variability, 

 ranging, as it does, from a grey through a number of inter- 

 mediate shades to a very dark green. This wide range of 

 variation may be seen in a single district, as I have found 

 in the locality in which I have chiefly observed it, viz. 

 South Devon, where however the darker forms predomi- 

 nate. By this great variability the species is much aided 

 in the struggle for existence in localities where stone walls 

 and rocks are as varied in hue as they are in South Devon. 

 Fig. 5 shows one of the darker forms which are extremely 

 well concealed on many of the walls. In this particular 

 instance the moth was rather more conspicuous than usual. 

 Fig. 6 is an example of the yellowish-green form, which 

 is less common than the other. It is however equally 

 well protected when at rcist on walls or rocks covered with 

 yellowish-green lichens. It is to be observed that the 

 moths of this genus adopt no special orientation in their 

 attitudes of rest, a fact which is in correspondence with 

 the irregular growth of lichen-masses on stone. 



