244 THE TENDENCY IN BIRDS TO RESEMBLE OTHER SrECIES. 
No. 19. The Flicker or Gokl-winged Woodpecker of North 
America is said to produce endless variations in plumage, 
to account for which several theories have been advanced 
(c/. Newton’s ‘Dictionary,’ p. 258), hut I must think, that 
of hybridism is untenable though supported by Mr. Elliott 
(‘Auk,’ 1892, p. 1G1). Perhaps here we may have some attempt 
at resemblance on a large scale, and in that way differing from 
those mentioned before. 
No. 20. It may well be that “resemblance” spontaneous, and 
more than occasional, has been at the bottom of some of the 
confusion which has reigned in the Pahnarctic Shrikes, Lanius, 
a group about which hardly two authors hold the same views. 
I believe no one doubts the genuineness of the Isabelline Night- 
jar shot in Notts in 1883, yet a very pale variety of the English 
Nightjar would be very difficult to distinguish from its south- 
eastern ally, albeit the pattern of plumage is slightly different, so 
this may be quoted as a possible case in point of two species 
resembling one another. Buff-coloured, sandy, and isabelline 
varieties of our Common Skylark are not very rare, and 
at once recall by their resemblance to them in colour the desert 
species of North Africa, such as Galerita macrurliyncha and 
Ammomanes desert, i, so like in tint to the sandy tracts which they 
inhabit. This, however, is no more than saying that an albino 
Hawk in Europe might be like the Australian Leucospizias (White 
Goshawk). Teal are occasionally taken with white rings round the 
neck like a Mallard Anas boscas, only narrower. This is resemblance 
by means of incipient albinism, and is said to have been also 
observed in the Wigeon ; but the vagaries of albinism are oftenest 
visible in the head and neck in the Ping Ouzel, Blackbird, and 
other Insessores. Thrushes which so resembled Blackbirds as to be 
taken for hybrids, and Blackbirds which resembled Ping Ouzels, 
have been from time to time recorded ; but I do not adduce these 
in evidence, attributing the former to melanism and the latter to 
incipient albinism. Indeed, to the former, may 'be also due, 
the Black Starling already mentioned. Suchctet cites no hybrid 
Starlings. The whole of his articles on the Passeres, and especially 
those on the Thrush tribe (up. 354, 792), are worth reading, in 
the light -of the different interpretations which some of the cases 
he quotes are capable of receiving. 
