among the surrounding foliage. An extreme case of this principle is seen in an Indian butterfly (Hallima). Besides the markings corresponding with those of the leaf, the wings themselves, when folded, trace out the exact contour of a leaf, the head of the butterfly forming the petiole attaching it to the branch. The protection to be derived from this imitation of surroundings is obvious. As an additional means of safety, in many species of butterflies the female has a more subdued colouring than the male, and, in some, so much so, that the male and female are mistaken for distinct species. More uncommon than the above imitation of surroundings, is the case where an insect affects a brilliant colouring for the sake of protection, a signal of danger, as it were, to birds and other enemies. An instance of this may be given. In South America there is a brilliantly coloured butterfly, which, probably on account of some poisonous or unpalatable quality is entirely safe from birds. Another butterfly, of quite a different species, apparently aware of this, has copied the gay colouring of the first butterfly so accurately as to deceive the birds themselves, and so is, in its turn, safe.
The remainder of this row of cases is occupied by the beetles, among which is conspicuous the destructive Colorado beetle, by the great variety of moths, and by specimens of lamp-shells, so-called from their resemblance to the old Roman lamps.
The next grade in the ascending series is furnished by the molluscs or soft-bodied animals, the greater number of which are known as shell-fish. Extending round the east and north sides of the lower gallery, and round a large portion of the west side, they form a large and valuable collection. Some of the shells are so small that the microscope has to lend its aid to discover the brilliant and intricate markings many of them possess. But leaving these to enthusiasts, a few of the larger ones may be noticed. The single valve of the Haliotis or mutton-fish, bright with almost every colour of the rainbow, a native of New Zealand, and common in all Maori pahs, needs no description. Perhaps the prettiest shell of all is that of the Paper Nautilus. It occurs in the female only, and differs in structure from the shell of all other molluscs in being secreted
