90 KEY TO THE BIRDS OF EASTERN NORTH AMERICA. 
* Group 2. Wing, 6 to 7.50 inches long. 
Crown, greenish or greenish black; legs, orange yellow in life. 
Ardea virescens. Green Heron, 
See No. 158. 
* Group 3. Wing, 8.50 to 11 inches long. 
Greater part of plumage, slaty blue; belly, slaty blue; head, tinged with purplish brown 
(adult). Ardeu cerulea. Little Blue Heron. 
See No. 157. 
* For directions for measurement, see page 9. 
