104 Brewster on Certain Polioptilce. 
Dimensions. Length, 4.50; extent,. 6. 10 ; wing, 1.84; tail, 1.80; tarsus, 
.73; bill, (culmen), .50; from nostril, .30. 
$ (No. 7192, National Museum) Fort Yuma. Similar to the $ but with 
the crown deep plumbeous ; the abdomen and crissum pale chestnut; the 
external webs of second pair of rectrices margined with white. 
Young £* (No. 2149, Coll, of R. Ridgwav) Saticoy, Cala., Nov. 24, 
1872. Coll. J. G. Cooper. Similar to the $ but with the plumbeous of 
the crown clearer ; the brownish wash beneath confined to the abdomen 
and crissum. the white of tail restricted to outer pair of rectrices and a 
narrow tipping on the second pair. 
Four specimens examined. 
Upon comparing the California bird with P. plumbea as rep- 
resented by my Arizona specimens, the following differences ap- 
pear. The ash of the upper parts is decidedly plumbeous in- 
stead of bluish ; the throat, breast and sides dull ashy instead of 
ashy-white ; the abdomen, crissum and under tail-coverts fulvous, 
in some specimens pale chestnut ; the light edging of the tail 
feathers confined to the outer pair of rectrices (with sometimes a 
slight tipping on the second pair) and on these restricted to the 
extreme tips and a narrow margin along the outer web ; the lining 
of the wings pearl-ash instead of white and the secondaries and 
tertials edged with light brown. There is no pure white any- 
where on the bird, and the general aspect beneath is nearly as dark 
as in the Cat-bird. 
The proportions also apparently differ. The bill and tarsi are 
longer and more slender than those of P. plumbea but the wings 
and tail, especially the latter, are generally shorter than in the 
specimens of plumbea which my collection embraces. 
These differences, which characterize all stages alike, are so 
decided and constant that I believe them to be of specific value. 
In view of the general law that Pacific coast birds tend to darker 
coloring than their affines from the interior it is of course not im- 
possible that a gradual transition will eventually be found to exist 
between these closely allied Gnatcatchers. Cooper, however, 
found both species in winter at Fort Mohave, where each preserved 
its distinctive characters,')' and my Fort Yuma specimen of cali- 
* It would be indeed remarkable if this species has no immature stage corresponding 
to that of P. plumbea. But putting aside some doubtful California citations, there is 
nothing to show that any such specimens have ever been taken. Mr. Stephens writes 
me that he has examined numerous California examples, but among them has found 
no spring males without the full black cap. 
f Birds of Cal., I, 1870, 37. 
