18 



Key. 



^SupArcit/ary Line 



Figure 1. 



Plumage areas of a typical bird. 



L Feet Fully Webbed — Two or three complete webs to each'^foot. 



A, Toes, four, 



a, Tarsus flattened. 



Figure 2. 



Loons p. 44. 



Figure 3. 



Figure 4. 



Figure 5. 



b, Closed wing longer than tail, except in some Jaegers (Figure 3) 

 and Terns (Figure 5), in which the rule only holds if the greatly 

 elongated central tail feathers of the former or the outer ones of 

 the latter are disregarded. Bills as shown 



Long-winged Swimmers — Gulls, Tern, Jaegers p. 48. 



