The question whether or not birds are good observers is a most interesting one. Unfortunately, hitherto, but little attention has been paid to the subject. The evidence available seems to point to the fact that birds, like savages, have sharp eyes only for certain objects—that is to say, for the things they are accustomed to look out for. All observers of nature must have noticed how quick a butcher-bird is to catch sight of a tiny insect upon the ground at a distance of some yards from his perch. On the other hand, it is said that when there is snow upon the ground wood pigeons will approach quite close to a man wearing white clothes and a white hat, provided he keep perfectly still. Finn once witnessed in Calcutta a sparrow pick up a very young toad, obviously by mistake, for it dropped it at once with evident distaste. Birds of prey are supposed to have remarkably good eyesight; yet they can readily be caught by a net stretched out before their quarry. They are not trained to be on the watch for such things as nets, and so do not appear to notice one when erected. It is thus our belief that the very perfection and detail of some so-called mimetic resemblances are a very serious objection to the theory of protective mimicry as enunciated by Professor Poulton and other Neo-Darwinians. There is yet a further objection to this theory, one which, in our opinion, is fatal to the hypothesis in its generally accepted form. A number of cases occur where two species, in no way related, show close resemblance to one another under such circumstances that neither can possibly derive any benefit from the likeness. The theory of protective mimicry is quite unable to explain these cases. This fact leads to a suspicion that, in the instances where the theory does at first sight appear to offer an explanation, the resemblance may also be due to mere coincidence. We may perhaps call the cases which the theory of mimicry is unable to account for “false mimicry,” but in so doing we must bear in mind the possibility that some, at any rate, of the examples of so-called mimicry may, on further investigation, prove to be nothing of the kind. “False” Mimicry among Mammals The Cacomistle of Mexico (_Bassaris astuta_), one of the raccoon family, has a grey body and long black-and-white ringed tail, just like the ring-tailed Lemur of Madagascar (_Lemur catta_); both are arboreal and about the same size, and this lemur’s colouration is exceptional in its family. The banded Duiker-buck of West Africa (_Cephalophus doriae_), has the same very unusual colouration as the thylacine or marsupial wolf of Tasmania, light brown, with bold black bands across the hinder part of the back, and the animals are about the same size. The dormouse of Europe closely resembles a small American Opossum (_Didelphys murina_), and a larger opossum (_D. crassicaudata_) is very like the Siberian Mink (_Mustela sibirica_).