236 NORTHERN ZOOLOGY. 



2. The Muscicapa altiloqua of Vieillot, which may either be, as Bonaparte observes, the 



V. olivacea, or the species here denominated longirostris. 



3. The Sijlvia gilva of Vieillot, which is probably the melodia of Wilson above noticed: the 



description is too loose and unsatisfactory to be applied to our bird.* 



4. The Vireo virescens of the same author, which may be this species, or another, much 



smaller, of which a wing only was brought home by the Expeditions. 



It is the misfortune of those who aim at accuracy, that they are either obliged 

 to give new names to species which they cannot find perfectly described, but 

 which, in fact, may not be new, — or they must assimilate their species to some 

 other, which eventually turns out to be totally distinct. Of two evils, we rather 

 choose to risk the former, since a striking instance of the latter is given in this 

 very group : the West Indian bird being perfectly different from that of North 

 America, with which, as it now appears, all writers have confounded it. 



A specimen of this species was procured, by Mr. David Douglas, on the banks 

 of the Colombia. It appears to have been a young bird, and is somewhat injured 

 by insects ; but we have attentively compared it with two other specimens f, one 

 from Brazil, the other from South Carolina, and all three agree in that particular 

 structure of the wing which is nearly the sole external distinction it possesses. 

 The essential differences, in short, between the two species in their outward 

 form is confined to the structure of their wings and to their respective sizes. 

 Olivaceus is larger, and has the first quill feather invariably much longer than 

 the fifth, a character which is conspicuous in seventeen specimens now before us. 

 Bartramii is much smaller, the colours rather brighter, the wings considerably 

 shorter and more rounded, and the first quill always shorter than the fifth. The 

 former seems confined to North America, the latter extends to Brazil. The com- 

 parative size of the bills in both is the same, but the length is variable. 



The following measurements will shew the differences of size between the 

 species more clearly. 



Vireo olivaceus. V. Bartramii, yng. V. Bartramii, adult. 





Inches. 



Inches. 



Inches 



length .... 

 ,, of the bill from the front 



5- 5 - 



5 



" 10 



4- e - 



4 



I o 



5i 3 o 



5 

 1 Tj 



„ of the wings 

 „ of the tarsus . 



Q 2 



7 



'2 6 - 



_R_ 



2- 8 - 

 hardly T ', 



— Sw. 



* " Cette espece a le bee et les pieds bruns ; la tete, le dessus du cou, et du corps gris : cette teinte est liglrement 

 nuancee de verdatre sur le dos. Longueur totale quatre polices, neuf lignes." — Ois. de T Am. Lev., f., p. 65. 

 f In Mr. Swainson's museum. 



