686 DR. J. C. MOTTRAM ON 



grey to very dark grey, the same result will be seen. It is easy 

 to see that, supposing the central square was an insect and that 

 the different tones placed outside were the various backgrounds 

 against which it would be likely to be seen, then the possession 

 of a checkered margin would be a great aid towards its con- 

 cealment. 



To further test this property of an interrupted margin, squares 

 were made as shown in text-fig. 3, 7-10 : these squares were 

 made so that after pattern-blending they all appeared of the 

 same tone. They were examined against a series of backgrounds 

 and it M'as found that, whereas 10 remained for the most part 

 sharp, the others showed blurred outlines ; the blurring effect in 

 the case of square 7 was not appreciably different from that of 

 8 and 9. It appears therefore that a comparatively narrow 

 broken margin is effective. 



Text-figure 4. 



Examples of marginal pat-terns : F=fringe of scales projecting from wing-margin. 



1. Dingy Skipper, Hesperia tayes $ , dorsal surface of anterior wing. 



2. Grizzled Skipper, S. malvce $ , dorsal surface of anterior wing : pattern con- 



iined to fringe. 



3. Common Bine, Li/ eana icarus c?, ventral surface of anterior wing : pattern of 



marginal e.ye-spots. 



4. Chiilk-hill Blue, i. cori/don ? , dorsal surface of anterior wing : pattern chiefly 



confined to fringe. 



5. Painted Lady, Fyrameis cardui, dorsal surface of posterior wing. 



6'. Long-tailed Blue, L. hwtica, ventral surface of posterior wing : pattern at some 

 distance from margin. 



A few examples of this mode of concealment are given in 

 text-fig. 4 : it may be mentioned that outline-masking in insects is 



