ARDEID.E — THE HERONS — NYCTUEIIODIUS. 63 



have seen is an adult female from Mount. Carniel, Illinois. This specimeu was shot from the nest, 

 and a perfectly developed e{,'g taken from the ovary ; consecpiently there <um be no doubt as to the 

 sex. lu this specimen the plumbeous is tliroughout of a clear, fine grayi.sli-blue tinge ; the rec- 

 trices, even, are dark bluish phimljeous (with a faint green reflection in certain lights), and are 

 distinctly bcn-dered with phnnljeous-l)lue. This fine example is nearly matclied by No. 17148, 

 National Museum, from the Tortugas, Florida (spring of 18()()). The opposite extreme is nearly 

 represented by another adult female, but jirobably 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 witli other sjiecimens examined ; the rectrices are 

 absuhitely uniform slaty idumbeous, 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 (383C, March 10), is almost precisely similar. 



An adult, in nuptial plumage (No. 67919), from the Talamanca district, Costa Eica, differs 

 from other specimens in full plumage in having several blue-ljlack feathers in the middle of the 

 crown. This specimen is also remarkable for its large size. 



Some specimens, ajiparentlv in their second year, resend.ile adults in full jdumage, except that 

 they lack the scapular and i)ccii>ital plume:-, and that the black of the head, especiall}' underneath, 

 is mixed with white feathers. Nos. 28062 and 67920 represent this stage. As a proof that the . 

 bro\vn 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 sulistances, it is rather a mark of im- 

 maturity, it may be stateil that lioth these immature specimens have the ferruginous stain very 

 strongly mai'ked, it being in the former sperimen 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 theinselves, idthout an actiud moult, is represented by No. 11892 (Tortugas, April 5). 

 In this, all the well-define<l stripes and streaks of the first stage have become obliterated, but at 

 the same time the somlire colors of this age are retained. The upper parts, incliidinfj the scapular 

 plumes, which are not onlij present, but well developed,''- are of a dark oily, sooty, brownish-gray, 

 with a faint green refleetiou 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 

 occijiital plumes. 



From the above, we may reasonably infer that the assumjition 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 regaixl 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 Galajiagos Islands is found a Nyctherodius which is said to be distinct from the common 

 species. Tiiis form we have seen only in tlie immature plumage, a description of which is given 

 below.- 



' It is probable that the species breeds in tliis plumage. 

 2 NvcTHERomus IWUl'ER (Scl. & .Salv.). 



" A'yclicorax vio/aceus," Dakwix, Zool. Beag. III. Birds, 1S41, 128 (Galapagos). 

 "Ardea violacca," Sl'XDF.v. P. Z. S. 1S71, 125 (Galapagos). 



Nycticorax pauper, Scl. & Salv. P. Z. S. Slay 12, 1870, 323, 327 (Galapagos). — Salvix, Trans. 



Zool. Soc. IX. ix. 1875, 498. 



Young $ , transitimi plumage : Head chiefly black, uniform on the sides of the pileura and occiput, 



the centre of tlie latter mixed with elongated light-brown feathers liaviiig darker mesial stripes. Stripe 



on side of the head, from the rictus over- the ear, liglit tawny brown ; malar region blue-black, with a 



few narrow whitisli streaks; chin and throat more heavily streaked with white. Upper jwrts in general, 



