320 KEY 'O THE BIRDS OF EASTERN NORTH AMERICA. 
FAMILY SYLVIID-E. 
Kinglets and Gnatcatchers. 
Size, small; length, less than 4.75 inches; wing, less than 2.50 inches ; 
first primary, very short. 
Gnateatcher, Kinglet. 
Back, bluish gray; outer tail feathers, mostly 
white. 
Blue-gray Gnatcatcher. 
Polioptila cerulea. 
See No. 557. 
Back, olive; no white patch on tail; crown, with patch of bright red (male) ; 
crown, olive (female). 
Ruby-crowned Kinglet. 
Iegulus calendula. 
See No. 556. 
Back, olive; no white patch on tail; crown, with 
patch of orange edged with yellow and black (male) ; 
crown, with yellow patch edged with black (female). 
Golden-crowned Kinglet. 
Regulus satrapa. 
See No. 55d. 
