281 
nosus, and many of the lesser scapulars with patches of silver 
grey. The longer scapulars, and secondaries, tipped conspicu- 
ously, and the former obscurely mottled, with greyish brown. 
In other forms of the same plumage, these tippings and 
mottlings are wanting, as are the grey patchings on the lesser 
scapulars, while the dark centres of the feathers are so broad, 
as to reduce the rufous buff to broad edgings. In some again, 
the rump, instead of being blackish brown, is rufous brown, 
broadly edged with deep rufous ; and in others, the upper tail 
coverts, instead of being bright rufous, with traces of brown bars, 
are deep brown, tipped with pale rufous. As the bars on the 
tail begin to appear, the colours of the upper surface appear to 
erow dingier; the bright rufous buff becomes rufous white, 
then dingy buff, and dingy yellowish white; the brown grow- 
ing paler and more earthy, and as the tail begins to assume the 
dingy earth brown tinge, the rufous or fulvous edgings to the 
feathers begin to disappear altogether, and we get to that 
nearly uniform, dull brown, upper surface, (whitened about the 
head, owing to the white feathers showing through,) already 
described. 
The great difficulty we meet with, in assigning any chronolo- 
gical value to these changes is, that the changes on the upper 
surface, do not correspond with those on the lower. 
It is easy enough to arrange any number of specimens, in 
what, looking at the upper or under surfaces only, appears a 
very perfect series, in which no links are wanting, but directly 
we turn the specimens over, all traces of any arrangement 
seems to vanish, and birds at the opposite ends of the chain, 
when arranged by the plumage of one surface, ought, if arranged 
according to that of the other, to be placed side by side. This 
provoking want of correspondence, in the changes of the plu- 
mage, of the two surfaces, has already been noticed, page 147, 
when treating of Aquila Imperialis, but it is much more conspi- 
cuous and perplexing in the present species, ‘The only points 
in which the changes in the upper and lower surfaces correspond, 
is, that as we approach the uniform, dull brown, upper surface 
stage, the whole of the colours of the lower surface, grow duller, 
and lose the rufous tinge. 
Taking now the typical form, of what I have styled B. Fudi- 
ginosus, the whole of the head, neck, cheeks, ear coverts, throat 
and breast, is a deep hair or umber brown, narrowly, and indis- 
tinctly margined, with dingy rufous, and the whole of the rest 
of the bird, except the primaries and tail feathers, are a more or 
less rich and deep hair brown, tinged with umber on the lower 
surface, and glossed with purple on the rump, upper tail coverts, 
longer scapulars and tertiaries. ‘The tail is silver grey, with a 
