460 THE ZOOLOGIST. 



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 sepa- 

 rated 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 Wood- 

 pecker, 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 



* Cf. Beddard, ' Animal Coloration,' 2nd edit. p. 47. 



