vein markings and leaf-like contour. This class includes most of the very large 

 green caterpillars, such as those of the Cecropia, Polyphemus, Luna and 

 Promethea moths, many of the Sphinxes, and, with modifications, the larva of 

 Basilona imperialis, etc. Most caterpillars protected by this counter shading 

 hang upside down, and are therefore, of course, dark on the helly and light on 

 the back, exactly the reverse of creatures which stand back-uppermost. (A few 

 larvae — some SphingidcB among the number — rest on the upper sides of twigs, 

 and are counter shaded accordingly, from dark on the back to light on the 

 belly, exactly like birds and beasts.) 



Plate XII, Fig. A, shows a Luna caterpillar in a natural position, a good 

 example of the full working of fully developed counter shading. By this 

 device the larva, hanging in proper position among leaves, is enabled to lack all 

 appearance of solidity, and to ' melt ' perfectly into the general, indeterminate 

 green of the mass of foliage which surrounds it. In addition to this purely 

 obliterative device, the caterpillar is furnished with leaf-vein-like bands and 

 a leaf -edge-like back-contour, so that if the eye of an enemy happens to detect 

 its surface as that of a distinct object separate from the general green, the larva 

 may still, by virtue of its perfect flatness of tone, greatly aided by these leaf-like 

 markings, merely pass for a flat leaf, or part of such a leaf. Without these 

 markings to further the deception, and to distract the observer's attention from 

 the larva's surface-texture, this, closely though it resembles that of leaves, would 

 often betray the creature, by its slight peculiarities of appearance. These 

 markings bring in an element of mimicry, inasmuch as they help the larva, 

 when he is revealed as a definite object, to pass for a leaf or leaf-portion no more 

 distant than he actually is from the observer, rather than picturing the back- 

 ground upon him. This is proved by the back-contour, which seems to mimic 

 the wavy edge of a single, foreground leaf, with its serrations of full size, rather 

 than reduced by distance ; and the vein markings also are in keeping with this 

 plan, being pronounced and large. Many, in fact nearly all, of our large green 

 caterpillars have this form of protective coloration, and the Luna is chosen 

 merely as one good type of the class. There are many fine examples of it 



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