42 S ELEMENTARY ZOOLOGY 



made by some animals. The chameleons of the tropics 

 change momentarily from green to brown, blackish, or 

 golden. There is a little fish (Oligocottns snyderi] com- 

 mon in the tide-pools of the Bay of Monterey in California 

 whose color changes quickly to harmonize with the rocks 

 it happens to rest above. Such changing coloration to 

 suit the surroundings may be called variable protective 

 resemblance. 



Very striking are those cases of protective resemblance 

 in which the animal resembles in color and shape, some- 

 times in extraordinary detail, some particular object or 

 part of its usual environment. This may be called special 

 protective resemblance. The larvae of the Geometrid 

 moths called inch-worms or span-worms are twig-like in 

 appearance, and have the habit, when disturbed, of stand- 

 ing out stiffly from the twig or branch on which they rest, 

 so as to resemble in attitude as well as color and mark- 

 ings a short or broken twig. To increase this simulation 

 the body of the larva often has a few irregular spots or 

 humps resembling the scars left by fallen leaves, and it 

 also lacks the middle prop-legs of the body common to 

 other lepidopterous larvae, which would tend to destroy 

 the illusion so successfully carried out by it. The common 

 twig-insect or walking-stick (fig. 162) with its wingless, 

 greatly elongate, brown or greenish body and legs is when 

 at rest quite indistinguishable from the twigs on which it 

 lies. Another excellent example of special protective 

 resemblance is furnished by the famous green-leaf insect 

 (Phylliuwi] of the tropics, which has broad leaf-like wings 

 and body of a bright green color with markings which 

 imitate the leaf-veins, and small irregular yellowish spots 

 which simulate decaying or stained or fungus-covered 

 spots in the leaf. Most striking of all, however, is the 

 large dead-leaf butterfly Kallima (fig. 163) of the East 

 Indian region. The upper sides of the wing are dark 



