192 VIREONID &. 
Described in 1851 from a specimen obtained by Cassin near Philadelphia}, this 
Vireo has gradually but slowly become known as an inhabitant of the whole of the 
eastern portion of North America from Hudson’s Bay southwards, the valley of the 
Mississippi being the area where it is most abundant and through which its main line 
of migration passes. As yet its presence has not been detected in Mexico, though it 
probably occurs in the southern States of that republic. In Guatemala it is abundant 
in the winter months, chiefly in Alta Vera Paz; but it is not confined to that portion of 
the country, as we have specimens obtained near Retalhuleu and on the slopes of the 
Volcan de Agua, and therefore in sight of and not far from the Pacific Ocean. Thence 
the species spreads to Costa Rica and the adjoining parts of the State of Panama. 
The Guatemalan specimens obtained by us prior to 1860 were descrjbed by Mr. Sclater 
as V. cobanensis®, under the impression that the species was distinct from V. philadel- 
phicus, with which they had previously been associated?._ Their identity was subse- 
quently proved by Prof. Baird, who had ample opportunity for comparing ‘the two 
birds 3. 
Vireo philadelphicus probably breeds throughout its North-American range; but up 
to 1874 neither nest or eggs had been discovered’. 
b!. Lemex spurius obvius. 
6. Vireo gilvus. 
Muscicapa gilva, Vieill. Ois. Am. Sept. i. p. 65, t. 84+. 
Vireo gilva, Scl. P. Z. S. 1858, p. 3027; Dresser, Ibis, 1865, p. 480°. 
Vireosylvia gilva, Scl. P. Z.S8. 1856, p. 298*; Baird, Rev. Am. B. i. p. 342°; Sumichrast, Mem. 
Bost. Soc. N. H. 1. p. 548°; Baird, Brew. & Ridgw. N. Am. B.i. p. 3687; Salv. Cat. Strickl. 
Coll. p. 112°. 
Vireosylvia gilva, var. swainsoni, Lawr. Bull. U.S. Nat. Mus. no. 4, p. 17°. 
Vireo gilvus swainsoni, Coues, B. Col. Vall. p. 501”. 
Obscure olivaceus, pileo cinerascentiore, capitis lateribus pallide fuscis; superciliis et corpore subtus gilvo- 
albidis, hypochondriis vix ochraceo-flavicantibus, alis (immaculatis) et cauda dorso fere concoloribus ; 
rostro corneo, mandibula pallidiore, pedibus plumbeis. Long. tota 4°8, ale 2-8, caude 2°05, rostri a 
rictu 0°7, tarsi 0-7. (Descr. maris ex San Pedro, Mexico. Mus. Ac. Cantabr.) 
Hab. Temperate NorrH Americal, Texas*, Arizona !°.—Muxico (Sallé*), San Pedro 
(Galeotti ®), State of Vera Cruz (Sumichrast °), Oaxaca (Boucard ?), Santa Efigenia 
(Sumichrast °). 
Two races of this species, an eastern and a western, have been recognized by many 
writers on North-American birds, the eastern race being the true V. gilvus, and the 
western V. swatnsoni, or, according to some recent nomenclature, V. gilvus swainsont. 
The western bird is a trifle smaller and greyer above, the underparts being whiter, 
hardly tinged with buff. But the differences are exceedingly slight, so much so that 
Dr. Coues expresses himself as without much confidence in the reality of the distinction 
