192 VIEEONIDiE. 



Described in 1851 from a specimen obtained by Cassin near Philadelphia i, 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 Eetalhuleu 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 Eica and the adjoining parts of the State of Panama. 



The Guatemalan specimens obtained by us prior to 1860 were described by Mr. Sclater 

 as V. cobanensis ^, under the impression that the species was distinct from V. pMladelr 

 phicus, with which they had previously been associated 2. Their identity was subse- 

 quently proved by Prof. Baird, who had ample opportunity for comparing the two 

 birds ^. 



Vireo philadelpkicus probably breeds throughout its North- American range ; but up 

 to 1874 neither nest or eggs had been discovered '^. 



b'. Bemex spurius obvius. 

 6. Vireo gilvus. 



Muscicapa gilvajYieiiLl. Ois. Am. Sept. i. p. 65j t. 34'. 



Vireo gilva, Scl. P. Z. S. 1858, p. 302 ^ ; Dresser, Ibis, 1865, p. 480 \ 



Vireosylvia gilva, Scl. P. Z. S. 1856, p. 298*; Baird, Rev. Am. B. i. p. 342'; Sumichrast, Mem. 



Bost. See. N. H. 1. p. 548 " ; Baird, Brew. & Ridgw. N. Am. B. i. p. 368 ' ; Salv. Cat. Strickl. 



Coll. p. 112 ^ 

 Vireosylvia gilva, var. swainsoni, Lawr. BuU. U.S. Nat. Mus. no. 4, p. 17°. 

 Vireo gilvus swainsoni, Coues, B. Col. Vail. p. 501". 



Obscure oUvaceus, pileo cinerascentiore, capitis lateribiis paUide fuscis; superciliis et corpore subtus gilvo- 

 albidis, hypochondriis vix ocbraceo-flavicantibus, alis (immaculatis) et Cauda dorso fere concoloribus ; 

 rostro corneo, mandibula pallidiore, pedibus plumbeis. Long, tota 4'8, alse 2"8, caudse 2'05, rostri a 

 rictu 0-7, tarsi 0*7. (Descr. maris ex San Pedro, Mexico. Mus. Ac. Cantabr.) 



Eab. Temperate North America ^ Texas ^ Arizona i^. — Mexico {Salle% 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. swainsoni, or, according to some recent nomenclature, V. gilvus swainsoni. 

 The western bird is a trifle smaller and greyer above, the underparts being whiter, 

 hardly tinged with bufi'. But the differences are exceedingly slight, so much so that 

 Dr. Coues expresses himself as without much confidence in the reality of the distinction 



