ARDEIDJE — THE HERONS — NYCTHERODIUS. 
63 
have seen is an adult female from Mount. Carmel, Illinois. This specimen was shot from the nest, 
and a perfectly developed egg taken from the ovary ; consequently there can be no doubt as to the 
sex. In this specimen the plumbeous is throughout of a clear, fine grayish-blue tinge ; the rec- 
trices, even, are dark bluish plumbeous (with a faint green reflection in certain lights), and are 
distinctly bordered with plumbeous-blue. This fine example is nearly matched by No. 17148, 
National Museum, from the Tortugas, Florida (spring of 1860). The opposite extreme is nearly 
represented by another adult female, but probably a younger bird, from the same locality, and 
obtained at about the same time and under nearly the same circumstances. In this specimen the 
plumbeous is everywhere much less bluish, and on the back and lesser wing-coverts is even very 
much obscured by a smoky tinge ; the black stripes of the back and wings show a very strong 
bottle-green reflection, which is not the case with other specimens examined ; the rectrices are 
absolutely uniform slaty plumbeous, without paler edges. The head is marked and colored as 
usual in fully adult specimens, and the forehead has a slight tinge of ochraceous anteriorly. A 
specimen from Fort Brown, Texas (3836, March 10), is almost precisely similar. 
An adult, in nuptial plumage (No. 67919), from the Talamanca district, Costa Rica, differs 
from other specimens in full plumage in having several blue-black feathers in the middle of the 
crown. This specimen is also remarkable for its large size. 
Some specimens, apparently in their second year, resemble adults in full plumage, except that 
they lack the scapular and occipital plumes, and that the black of the head, especially underneath, 
is mixed with white feathers. Nos. 28062 and 67920 represent this stage. As a proof that the 
brown tinge on the crown of this species has nothing to do with season or sex, but that, on the 
contrary, if not an entirely accidental stain from foreign substances, it is rather a mark of im- 
maturity, it may be stated that both these immature specimens have the ferruginous stain very 
strongly marked, it being in the former specimen deeper than I have ever seen it in any adult, 
and so dark in places as to appear of a dark sepia- or snuff-brown tinge. 
A younger stage of plumage than the above, and one which perhaps illustrates a change in color 
of the feathers themselves, without an actual moult, is represented by No. 11892 (Tortugas, April 5). 
In this, all the well-defined stripes and streaks of the first stage have become obliterated, but at 
the same time the sombre colors of this age are retained. The upper parts, including the scapular 
plumes, ivliich are not only present, hit, well developed, 1 are of a dark oily, sooty, brownish-gray, 
with a faint green reflection in certain lights ; many of the feathers darker medially (especially 
the wing-coverts and scapular plumes), the wing-coverts having well-defined pale margins. The 
forehead and middle of the crown are rich brown, of a shade between cinnamon and sepia ; the 
occiput uniform blue-black ; the malar region and throat streaked with blue-black and white. 
The lower parts much as in the first plumage, but the stripes more indistinct. There are no 
occipital plumes. 
From the above, we may reasonably infer that the assumption of the perfect adult plumage is 
a very gradual process, and not accomplished at a single, nor solely by several moults ; but that 
after each moult a gradual change in the colors of the feathers takes place, — a fact which is cer- 
tainly established with regard to many birds. Those specimens in which the plumbeous is of a 
clear, fine bluish cast are therefore to be considered the oldest individuals, and the more sombre 
ones younger. 
In the Galapagos Islands is found a Nyctheroclius which is said to be distinct from the common 
species. This form we have seen only in the immature plumage, a description of which is given 
below. 2 
1 It is probable that the species breeds in this plumage. 
2 Nyctherodius pauper (Scl. & Salv.). 
“ Nycticorax viulaceus,” Darwin, Zool. Beag. III. Birds, 1841, 128 (Galapagos). 
“Ardea violacea," Sundev. P. Z. S. 1871, 125 (Galapagos). 
Nycticorax pauper, Scl. & Salv. P. Z. S. May 12, 1870, 323, 327 (Galapagos). — Salvin, Trans. 
Zool. Soc. IX. ix. 1875, 498. 
Young $ , transition plumage : Head chiefly black, uniform on the sides of the pileum and occiput, 
the centre of the latter mixed with elongated light-brown feathers having darker mesial stripes. Stripe 
on side of the head, from the rictus over the ear, light tawny brown ; malar region blue-black, with a 
few narrow whitish streaks; cliin and throat more heavily streaked with white. Upper parts in general, 
