The movements, as well as the shape and colour of the insect imitated, are mimicked. I one day observed what appeared to be a hornet, with brown semi-transparent wings and yellow antennae. It ran along the ground vibrating its wings and antennae exactly like a hornet, and I caught it in my net, believing it to be one. On examining it, however, I found it to belong to a widely different order. It was one of the Hemiptera, Spiniger luteicornis (Walk.), and had every part coloured like the hornet (Priocnemis) that it resembled. In its vibrating coloured wing-cases it departed greatly from the normal character of the Hemiptera, and assumed that of the hornets. All the insects that have special means of protection, by which they are guarded from the attacks of insectivorous mammals and birds, have peculiar forms, or strongly contrasted, conspicuous colours, and often make odd movements that attract attention to them. There is no attempt at concealment, but, on the contrary, they appear to endeavour to make their presence known. The long narrow wings of the Heliconii butterflies, banded with black, yellow, and red, distinguish them from all others, excepting the mimetic species. The banded bodies of many wasps, or the rich metallic colours of others, and their constant jerky motions, make them very conspicuous. Bees announce their presence by a noisy humming. The beetles of the genus Calopteron have their wing-cases curiously distended, and move them up and down, so as to attract attention; and other species of Lampyridae are phosphorescent, holding out danger signals that they are not eatable. The reason in all these cases appears to be the same as Mr. Wallace has shown to hold good with banded, hairy, and brightly coloured caterpillars. These are distasteful to birds, and, in consequence of their conspicuous colours, are easily known and avoided. If they were like other caterpillars, they might be seized and injured before it was known they were not fit for food.* (* In a paper on "Mimicry, and other Protective Resemblances amongst Animals" first published in the "Westminster Review" July 1867, afterwards in "Natural Selection", Wallace has elaborately discussed this question. My observations are supplemental to his and to the original ones of Bates.) (PLATE 23. HORNET AND MIMETIC BUG)