Allen and Brewster on Colorado Birds. 
l 59 
1SS.5.] 
Geothlypis trickas occidentalis var. nov. Ch. subsp. Similis G. tri- 
chce sed cauda longiore ; colore supra pallidiore et flaviore ; colore infra 
magis flavicante et extento ; alba striga in pileo latiore et puriore. 
$ adult (No.. 5550, Coll. W. B., Truckee River, Nevada, May 4, 1881). 
Upper parts nearly uniform pale yellowish-olive^ with a tinge of brown 
on the occiput; throat, jugulum, breast, anterior portion of abdomen, 
and under tail-coverts rich, pure yellow; sides of body warm ochraceous 
brown strongly tinged with yellow; middle of abdomen anteriorly creamy 
white; a black mask on the front and sides of the head bordered 
behind by a broad band of creamy white, slightly tinged with bluish; 
much concealed yellow on the feathers of the crown. 
Dimensions: Wing, 2.32; tail, 2.30; culmen, .55. 
Habitat: Pacific and Middle Provinces of the United States. 
The differences which distinguish this race from trichas proper, 
although somewhat difficult of description, are readily appreciable upon 
a comparison of specimens ; they may be briefly summed as follows : 
Occidentalis is somewhat larger than trichas and its tail is disproportion- 
ately longer. Its upper parts are always paler and usually yellower; the 
yellow of the under parts is decidedly richer and purer, and extends 
much further down on the abdomen, frequently tinging nearly all of the 
body beneath ; the flanks are paler and more ochraceous ; the white of 
the head purer and generally broader. 
I have not seen var. melanops Of Mexico but judging from descriptions 
the present race approaches it rather more closely than it does trichas. 
A decided approach is furnished by a specimen from Cienega Station, 
Arizona (No. 5906), which is even yellower above than my type of occi- 
dentalism while the yellow of the under parts extends over nearly all the 
abdominal region and strongly tinges the flanks. This bird agrees very 
closely with Baird’s description of G. melanops but is considerably 
smaller. In my paper on the Arizona collection I referred it to G. trichas , 
but I am now inclined to consider it an intermediate between the present 
race, occidentalism and melanops of Mexico. 
31. G-eothlypis macgillivrayi. Macgillivray’s War- 
bler. — First seen May 4. Soon became frequent, and continued 
more or less common in willows along creek bottoms till the end 
of the month. 
32. Xcteria virens. Yellow-breasted Chat. — First 
observed May 13 ; others seen and heard on following days. 
33. Myio&ioctes pusillus pileolatus. Black-capped 
Flycatching Warbler. — -First seen May 12; of frequent 
occurrence later in willow thickets along streams. 
34. Setophaga ruticilia. Redstart. — First seen May 18. 
Not common. 
35. Pyranga ludoviciana. Louisiana Tanager. — Ar- 
rived in large numbers May 12, and continued common. 
