io 6 
Brewster on Certain Polioptilce. 
surprised to find that this supposed distinctness, inter se , apparent- 
ly rests upon pretty much the Same general grounds as has that of 
P. plumbea and P. melanura . The latest information regarding 
them appeared in Godman and Salvin’s “Biologia Centrali- 
Americana,” Part II, November, 1879, where their differential 
characters are set forth as follows : 
Polioptila nigriceps . U P. ccerulece similis, sed pileo toto cum 
loris et superciliis nitenti-nigris.” 
Polioptila bilineata. U P. nigricipiti affinis, sed loris et 
superciliis albis, striga postoculari tantum nigra, capiti nigro 
conjuncta.” 
Polioptila albiloris. U P. nigricipiti affinis, sed loris (nec 
superciliis) albis distinguenda.” 
If, by the above, we are to understand that P. nigriceps differs 
from P. ccerulea only in having “ the whole pileum, with the 
lores and upper eyelids, shining black ” it is of course separable 
from P. plumbea by the different coloring of the tail feathers, 
which would be like those of P. ccerulea. But in view of the age- 
variations which occur in P. plumbea , we are certainly warranted 
in entertaining a suspicion that bilineata and albiloris are only 
the immature stages of P. nigriceps. 
The condition known as P. bilineata is almost exactly repro- 
duced, relatively, by my specimen No. 4981, which has the lores 
and upper eyelids ashy-white ; while that called albiloris is very 
nearly duplicated by No. 4983 in which the lores remain ashy- 
white while the black of the crown encroaches on the white of 
the eyelids. 
The English ornithologists are evidently in some perplexity re- 
garding these allied forms, for in some general remarks which follow 
the specific matter they observe : “ Having thus given some account 
of the three forms of black-headed Polioptilce found in Central 
America ( P. nigriceps with the lores wholly black, P. albiloris 
with the lores white, and P. bilineata with both lores and supercili- 
aries white) it remains to consider the position of certain specimens 
which seem to have intermediate characters connecting two or all 
of these forms together. These birds were obtained, with a female 
of the true P. bilineata , near La Union in San Salvador, and have 
the lores black, with a few white feathers intermingled. . . . Putting 
P. albiloris aside, and observing the distribution of P. nigriceps 
and P. bilineata , we find the curious fact that the ranges of these 
