256 



DR. J. C. MOTTRAM ON CONCEALMENT BY 



the insect's wing by distinct black or white lines (only black lines 

 are shown in the diagrams). 



The distribution of these types is given in the Table on p. 257, 

 where it can be seen that "Surface Disruption by Contrast" occurs 

 in the Geometers in 69 out of 276 insects. In the Noctuas the 

 patterns occur 34 times in 311 insects, in the Cuspidates 11 in 33, 

 and in the Khopalocera 10 in 60. 



It follows that this method is often used for purposes of con- 

 cealment amongst the Lepidoptera ; numerous examples are also 

 to be found in the patterns of Vertebrates. 



Surface disruption can also be produced by the representation 

 of solid objects on a flat surface : this, indeed, is the method 

 chiefly employed by the artist. This method is very often found 

 in the pattern of animals generally combined with "Outline 

 Disruption " and " Surface Disruption by Contrast." Examples 



The Oleander Hawk-Moth (Chcerocampa nerii). From ' The Natural History of 

 British Butterflies and Moths,' by Edward Newman, F.L.S., F.Z.S. See text 

 below : reference is made only to the fore wings ; the hind wings are more or 

 less concealed by the fore wings in the position of rest. 



are shown in text-fig. 2, C and D ; in C all three methods are 

 combined, in D surface disruption by solidity with contrast. No 

 better example of snch combinations of methods can be found 

 than Chcerocampa nerii illustrated in text-fig. 4 ; iu this insect 

 the components of the pattern break out at the margin, are shaded 

 to represent excrescences and depressions, and are separated from 

 each other by well-defined white and black lines. 



Opportunity is here taken to call attention to the fact that 

 many small details of pattern are of value in concealment ; it 

 would seem dangerous therefore to conclude on negative evidence, 

 that small differences such as often distinguish species can have 

 no value in the struggle for existence. 



