The upper figure represents two of the Geometra or Looper Caterpillars, as they appear when at rest, and affixed to a twig. This appears to be a singular attitude of rest, but it is one in which they delight, and in which they remain for hours together, the claspers at the end of the body tightly grasping the branch, and the whole body held out so straight and motionless that it is hardly possible to believe that a veritable twig is not before the eye. The colour is that of the twig, and the different segments of the body look exactly like the little irregularities and projections of a young twig. I have more than once seen a novice in entomology unable to distinguish these larvæ, even when the branch was pointed out, and there were several upon it. Just below the Loopers, and on the left hand of the illustration, is shown the well-known Leaf-insect (_Phyllium_). These strange beings have the elytra and the flattened appendages of the legs so exactly like leaves that the most experienced eye can scarcely distinguish them from the leaves among which they are placed. Even when they have been on a small plant, such as a myrtle in a flower-pot, I have had the greatest difficulty in finding them, and have seen people examine the plant, and then go away declaring that no insects were on it. On the right hand, and just below the looper caterpillar, is the common Lappet-moth of this country, shown in its position of rest. When it assumes this attitude, it looks exactly like a withered leaf, the resemblance extending not only to the form, but the colour. All entomologists are familiar with many similar examples in insect life. The common Tortoise-shell Butterfly, for example, has a way of settling on patches of red soil, with which it harmonizes so well that it can hardly be seen. The various moths, also, are in the habit of resting on tree-bark, palings, and other objects, to which they instinctively know that they assimilate in hue. Many a beginner in entomology will pass a wooden fence or a wall, and not see an insect on either, while an adept will follow him and take twenty or thirty good specimens. The last figure in the illustration represents a Ptarmigan (_Lagopus vulgaris_) in its winter dress. These birds have two differently coloured dresses, one for summer and the other for winter, and both adapted for concealment by imitation. In the former dress it is mottled with various shades of blackish brown, yellow, and white. As the bird is in the habit of settling among the grey lichen-covered stones on the sides of rocky hills, these colours harmonize so exactly with them that a Ptarmigan may almost be trodden upon before it is perceived.