Bates concludes that the Leptalis first varies; and when a variety happens to resemble in some degree any common butterfly inhabiting the same district, this variety, from its resemblance to a flourishing and little persecuted kind, has a better chance of escaping destruction from predaceous birds and insects, and is consequently oftener preserved; "the less perfect degrees of resemblance being generation after generation eliminated, and only the others left to propagate their kind.

" So that here we have an excellent illustration of natural selection.

Messrs.

Wallace and Trimen have likewise described several equally striking cases of imitation in the Lepidoptera of the Malay Archipelago and Africa, and with some other insects.

Mr.