Henry Walter Bates’s paper on the phenomenon of mimicry in butterflies’ was read at the Linnean Society of London on November 21, 1861-three days short of the second anniversay of Darwin’s publication of On the Origin of Species. In this paper Bates described surprising resemblances among butterfly specimens of different families. He explained these similarities of coloration and pattern on “Mr. Darwin’s principles,” accepting both the general principle of evolution and the mechanism of natural selection. Without equivocation, he wrote, “I believe the case offers a most beautiful proof of the truth of the theory of natural selection. It also shows that a new adaptation, or the formation of a new species, is not affected by great and sudden change, but by numerous small steps of natural variation and selection.“2 According to Bates, natural selection had been acting over a long span of time, allowing for the gradual acquisition of a deceptive appearance in Leptalis butterflies, ordinarily a prey for many insectivorous birds. The mimicking Leptalis looked very much like the Heliconiidae, a family of butterflies which contained a number of species that were distasteful to many birds; Leptalis consequently were spared predation, once birds learned the pattern to avoid. The beautiful analogy of