The reptiles offer us many good examples of mimicry. Most arboreal lizards wear the colour of the leaves upon which they feed; the same is true of the whip-snakes and the tiny green tree-frogs. A striking example of successful camouflage is found in the case of a North American frog whose home is on lichen-covered rocks and walls, which he so closely imitates in colour and pattern as to pass unnoticed so long as he remains quiet. I have seen an immense frog, whose home was in a damp cave, with large green and black spots over his body precisely like the spots on the sides of his home. _Author Note:_ The word "mimicry" as used here implies a particular kind of resemblance only, a resemblance in external appearance, never internal, a resemblance that deceives. It does not imply voluntary imitation. Both the words "mimicry" and "imitation" are used to imply outward likeness. The object of the outward likeness or resemblance is to cause a harmless or unprotected animal to be mistaken for the dangerous one which he oftentimes imitates; or to aid the unprotected animal in escaping unnoticed among the surroundings he may simulate. A splendid example of pure bluff is shown in the case of the harmless Australian lizard, known scientifically under the name of _chlamydosaurus kingii_. When he is undisturbed he seems perfectly inoffensive, but when he becomes angry, he becomes a veritable fiend-like reptile. In this condition he stands up on his hind legs, opens his gaping mouth, showing the most terrible teeth, which, by the way, have never been known to bite anything. Besides this forbidding display he further adds to his terrible appearance by raising the most extraordinary frill which is exquisitely decorated in grey, yellow, scarlet, and blue. This he uses like an umbrella, and if in this way he does not succeed in frightening away his enemy, he rushes at him, and lashes him with his saw-like tail. Even dogs are terrified at such camouflage and leave the successful bluffer alone. In all parts of the tropics are tree-snakes that lie concealed among the boughs and shrubs. Most of them are green, and some have richly coloured bands around their bodies which look not unlike gaily coloured flowers, and which, no doubt, attract flower-seeking insects and birds. Among these may be mentioned the deadly-poisonous snakes of the genus _elaps_ of South America. They are so brilliantly provided with bright red and black bands trimmed with yellow rings that it is not uncommon for a plant collector to attempt to pick them up for rare orchids!