68 
Birds of Celebes: Balconidae. 
largest collections of Celebesian birds of prey — the I.eyden'), British, and 
Norwich Museums, and the Duivenb ode-collection reported upon by Prof. 
W. Blasius — Pernis celehensis numbered in all 11 skins, 8p. lanceolatus 22. 
There are before us in Dresden 5 of the former and 7 of the latter. 
Supposing — which is probably not the case, since birds are better field- 
ornithologists than most naturalists — that the birds etc., which suffer from the 
frequent depredations of the Hawk-eagle, do not at once discriminate its dif- 
ferences from the Honey-buzzard, they will avoid both species with dread; but 
it is more likely that the differences of size, structure, flight and general bear- 
ing cause the dangerous species to be detected, possibly even before its peculiar 
coloration is made out. 
Moreover, in the Philipines, as will be noticed presently, a Spizaetus, 
S. philip)pensis^ has been found closely resembling the Celehesian species, though 
the bird is unsatisfactorily known, but in these islands Pernis celehensis is re- 
presented by the highly variable P. ptilonorhynchus. Also in Malacca and Sumatra 
a Pernis has been described as showing much similarity to P. celehensis, but in 
these quarters the Hawk-eagle is S. limnaetiis, which seems to be a very vari- 
able species and can by no means be said to match the Honey-buzzard, ex- 
cept that, perhaps, the latter possesses the same quality of great variability in 
common with it. 
Furthermore, a type of plumage, bearing much resemblance to that of the 
adult Pernis and Spizaetus of Celebes, is seen in a South American Buzzard, 
Buteo melatiolenais Vieill. Spizaetus mauduyti of South America also bears some 
resemblance to the Pernis and Spizaetus of Celebes. 
If we were to seek for cases of close resemblance among birds of different 
genera not occurring in the same locality, we are confident that many might be 
found. To mention two: Spilornis holospilus of the Philippines is very like Circus 
assimilis J. & S. of Celebes and Australia in its coloration, and Ninocc punctulata 
of Celebes to Glaucidium jardini Bp. of S. America. Here the theory of mimicry 
is, of course, worthless. Touching the albescent plumage of the young, so 
completely different from the adult dress, those who maintain the theory of 
mimicry might perhaps here advance the suggestion that the causes, whatever 
they may be, by which one species is advantaged by resembling the other were 
the same in past ages as today; consequently, when the one was albescent, the 
other must needs become albescent too, and when the first assumed its present 
adult plumage, the other must needs follow it in this variation; while phylo- 
genetic reasons here as elsewhere come in to account for the repetition in imma- 
ture birds of what had been gone through by their ancestors. 
As containing an alternative explanation to that of Mr. Wallace, the 
phylogenetic relationship of the two forms, Pernis celehensis and Spizaetus lanceo- 
1) Since tlie publication of Scblegel’s “Revue”, the number of specimens of P. celehensis has been in- 
creased to 11. 
