Page:The Zoologist, 4th series, vol 3 (1899).djvu/490

460 and in other ways. Moreover, there is a variety of this form which is in the same way exceedingly like the form prorsa. A closer examination of the insect showed that it did not belong to this species at all, or even to the same genus; it is a member of another genus, Phyciodes. "If," says Dr. Seitz, "these were found in our country, no one would doubt that this was a case of mimicry as perfect as any which exists." It might be suggested that it is a case of mimicry, but the mimicking and mimicked forms have each gone their own way, one migrating to one country, and one to another; they might possibly at one time have both lived in North America, and later on separated, one going south and the other east, crossing over into Asia by way of Behring's Strait. Such an explanation would be, as Dr. Seitz points out, entirely contrary to what is known of the distribution of these insects; for the genus Araschnia is absolutely confined to the Old World, and Phyciodes to the New World. Of course it may be contended that the case does not apply, as it is an integral axiom in the theory of mimicry that the mimicker and the mimicked must, and are, always found together in the same part of the world, or that one of them may have become extinct. But here we see the phenomenon can be observed in widely separated habitats, and in birds one cannot help being amazed at the great superficial resemblance between the Secretary Vulture (Serpentarius secretarius) of South Africa, and the Brazilian Seriema (Cariama cristata).

Mr. J.H. Gurney has given twenty cases, "On the tendency in Birds to resemble other Species":—"On three occasions adult males of our British Sparrow-Hawk (Accipiter nisus) have been shot in this country, which so far resembled the South African (A. rufiventris, Smith) as to have the breast and under parts a clear rufous without any transverse bands (cf. 'Ibis,' 1893, p. 346). Buzzards which were indistinguishable from the rufous North African Buzzard (Buteo desertorum) have been killed in England three or four times (cf. 'Ibis,' 1889, p. 574).... In 1861 an example of Picus major, our Greater Spotted Woodpecker, obtained in Shetland, varied so as a little to resemble P. leuconotus, the White-backed Woodpecker, and was even figured as such in Gould's 'Birds of Great Britain.'... Snipes