conspicuous. On older and larger ones the lines are diagonal, like the nerves of leaves. Conspicuous caterpillars are generally either nauseous in taste, or protected by hairs.

I say "generally," because there are some interesting exceptions. The large caterpillars of some of the Elephant Hawkmoths are very conspicuous, and rendered all the more so by the presence of a pair of large eyelike spots. Every one who sees one of these caterpillars is struck by its likeness to a snake, and the so-called "eyes" do much to increase the deception. Moreover, the ring on which they are placed is swollen, and the insect, when in danger, has the habit of retracting its head and front segments, which gives it an additional resemblance to some small reptile. That small birds are, as a matter of fact, afraid of these caterpillars (which, however, I need not say, are in reality altogether harmless) Weis

mann has proved by actual experiment. He put one of these caterpillars in a tray, in which he was accustomed to place seed for birds. Soon a little flock of sparrows and other small birds assembled to feed as usual. One of them lit on the edge of this tray, and was just going to hop in, when she spied the caterpillar. Immediately she began bobbing her head up and down in the odd way which some small birds have, but was afraid to go nearer. Another joined her and then another, until at last there was a little company of ten or twelve birds all looking on in astonishment, but not one ventured into the tray; while one bird, which lit in it unsuspectingly, beat a hasty retreat in evident alarm as soon as she perceived the caterpillar. After waiting for some time, Weismann removed it, when the birds soon attacked the seeds. Other caterpillars also are probably protected by their curious resemblance to spotted snakes. One of the large Indian caterpillars has even acquired the power of hissing.

Among perfect insects many resemble closely the substances near which they live. Some

moths are mottled so as to mimic the bark of trees, or moss, or the surface of stones. One beautiful tropical butterfly has a dark wing on which are painted a series of green leaf tips, so that it closely resembles the edge of a pinnate leaf projecting out of shade into sunshine.

The argument is strengthened by those cases in which the protection, or other advantage, is due not merely to colour, but partly also to form. Such are the insects which resemble sticks or leaves. Again, there are cases in which insects mimic others, which, for some reason or other, are less liable to danger. So also many harmless animals mimic others which are poisonous or otherwise well protected. Some butterflies, as Mr. Bates has pointed out, mimic others which are nauseous in taste, and therefore not attacked by birds. In these cases it is generally only the females that are mimetic, and in some cases only a part of them, so that there are two, or even three, kinds of females, the one retaining the normal colouring of the group, the other mimicking another species. Some spiders

closely resemble Ants, and several other insects mimic Wasps or Hornets.

Some reptiles and fish have actually the power of changing the colour of their skin so as to adapt themselves to their surroundings.

Many cases in which the colouring does not at first sight appear to be protective, will on consideration be found to be so. It has, for instance, been objected that sheep are not coloured green; but every mountaineer knows that sheep could not have had a colour more adapted to render them inconspicuous, and that it is almost impossible to distinguish them from the rocks which so constantly crop up on hill sides. Even the brilliant blue of the Kingfisher, which in a museum renders it so conspicuous, in its native haunts, on the contrary, makes it difficult to distinguish from a flash of light upon the water; and the richlycoloured Woodpecker wears the genuine dress of a Forester- the green coat and crimson

cap.

It has been found that some brilliantly coloured and conspicuous animals are either nauseous or poisonous. In these cases the

brilliant colour is doubtless a protection by rendering them more unmistakable.

COMMUNITIES

Some animals may delight us especially by their beauty, such as birds or butterflies; others may surprise us by their size, as Elephants and Whales, or the still more marvellous monsters of ancient times; may fascinate us by their exquisite forms, such as many microscopic shells; or compel our reluctant attention by their similarity to us in structure; but none offer more points of interest than those which live in communities. I do not allude to the temporary assemblages of Starlings, Swallows, and other birds at certain times of year, nor even to the permanent associations of animals brought together by common wants in suitable localities, but to regular and more or less organised associations. Such colonies as those of Rooks and Beavers have no doubt interesting revelations and surprises in store for us, but they have not been as yet so much studied