Origin of Species Variorum

homopterous insect as a moth. We see something of the same kind even in our domestic varieties, as in the thickened stems of the common and Swedish turnip. The resemblance of the greyhound and racehorse is hardly more fanciful than the analogies which have been drawn by some authors between widely distinct animals. On my view of characters being of real importance for classification, only in so far as they reveal descent, we can clearly understand why analogical or adaptive characters, although of the utmost importance to the welfare of the being, are almost valueless to the systematists. For animals, belonging to two most distinct lines of descent, may readily have become adapted to similar conditions, and thus have assumed a close external resemblance; but such resemblances will not reveal— will rather tend to conceal their blood-relationship. .. .. .. .. .. .. We can thus also understand the apparent paradox, that the very same characters are analogical when one class or one order is compared with another, but give true affinities when the members of the same class or order are compared together: thus, the shape of the body and fin-like limbs are only analogical when whales are compared with fishes, being adaptations in both classes for swimming through the water; but the shape of the body and fin-like limbs serve as characters exhibiting true affinity between the several members of the whale family; for these cetaceans agree in so many characters, great and small, that we cannot doubt that they have inherited their general shape of body and structure of limbs from a common ancestor. So it is with fishes. ↑

The most remarkable case of analogical resemblance ever recorded, though not dependent on adaptation to similar conditions of life, is that given by Mr. Bates with respect to certain butterflies in the Amazonian region