Page:The Zoologist, 4th series, vol 3 (1899).djvu/569

Rh Its larva feeds on sallow and willow. Petasia cassinea is said in the daytime "to sit upon old posts and railings, and is very hard to see, from its close resemblance to a bit of decayed wood, or to the greyish-brown lichens. Its extended and tufted feet, and rough scales at the edge of the fore wings, all help to complete the deception." Cymatophora duplaris exhibits a purpose in active mimicry of the highest description, both as a caterpillar and a perfect moth. The larva during the day "conceals itself in a habitation formed of green leaves united by silken threads upon the tree. At night it comes forth to feed." The moth sits in the daytime on the branches of trees. "When shaken out it falls straight to the ground, and lies among the dead leaves." Arsilonche venosa, in colour and markings, like those of so many other fen-frequenting species, is accurately suited to its habit of hiding in the daytime among the dead leaves of reed, sedge, and marsh-grasses. Agrotis ashworthii "sits in the daytime on limestone rocks, or hides among loose stones. In appearance it closely resembles the blue limestone, and it has the sagacity to hide itself in chinks and crevices, where this resemblance greatly assists in its concealment." All these examples scarcely bear out an automatic or semi-automatic action; we seem to see among these lowly organised insects—referring, of course, to sense organs—a capacity and endeavour to use their environmental resemblances to the best advantage. There may be much heredity in such an aptitude, but the intelligent concealment would not be questioned if practised by the higher animals.

The instances of active mimicry just given almost appertain to decorative art, and in fact represent the impostor who with borrowed plumes flaunts in the open. We now resume the series of more modest simulation, in which advantage is taken of similarly coloured objects by which concealment may be effected. These may nearly be said to reflect the methods of the impostors who attach themselves to majorities, winning causes, and crowds, where they are submerged in resemblances, and, undetected, reap the corresponding advantage. The Australian genus of Sea-