432 Birds of Colorado 
C. Tenth primary longer, from 4 to 4 of the ninth. 
a. Larger—wing over 2-5; upper-parts grey, no olive. 
V. vicinior, p. 438. 
b. Smaller—wing under 2-5; upper-parts olive-green. 
V. belli, p. 437. 
Genus VIREOSYLVA. 
Medium-sized or small Vireos, with a bill somewhat variable in 
length, but generally rather slender, narrow and compressed ; its 
depth at the base not more than half the distance from the nostril 
to the tip; culmen straight with abruptly down-curved tip; wing 
long and pointed, the tenth (outer) primary either rudimentary and 
wholly concealed, or if present, narrow and pointed and less than } 
the length of the ninth; ninth primary longer than the fourth ; tail 
shorter than the wing, nearly even; wings without bars. 
This genus containing a considerable number of species, ranges over 
the whole of temperate and tropical America. (For key, see p, 431). 
Red-eyed Vireo. Viéreosylva olivacea. 
A.O.U. Checklist no 624—Colorado Records—? Allen 72, p. 176; 
Thorne 87, p. 264; Cooke 97, pp. 19, 112, 168, 218; Henderson 05, 
p. 421; 07, p. 239 ; H. G. Smith 08, p. 189. 
Description.—Male—Crown slaty-grey, faintly margined with a 
narrow line of dusky ; rest of upper-parts dull olive-green ; wings and 
tail dusky, edged with olive-green ; a white superciliary line extending 
over the ear-coverts, and a dusky loral stripe in front of the eye ; below 
white tinged on the flanks and under tail-coverts with yellowish-olive ; 
under wing-coverts pale yellow; tenth (outer) primary obsolete; iris 
brownish-red, bill dusky grey, lower mandible rather paler, legs dusky. 
Length 5-5 ; wing 3-10; tail 2-10; culmen -50; tarsus -63. 
The sexes are alike. A young bird is brown above and has the post- 
ocular streak rather indistinct. 
Distribution.—Breeding throughout temperate North America, 
except in arid districts, from British Columbia and Nova Scotia to 
western Texas and Florida; in winter south to the Bahamas and 
through Mexico to Brazil and Bolivia. 
The Red-eyed Vireo is a somewhat rare summer bird in the plains 
country of eastern Colorado and does not extend into the foothills or 
mountains. It arrives late in May and departs again in September. The 
following are the recorded occurrences: Fort Lyon May 29th, three 
times (Thorne) ; Loveland, once seen May 12th by Prof. W. Osburn, 
and Denver, one seen May 22nd, 1892, by H. G. Smith (Cooke) ; Limon, 
