18 
Key. 
Superciliory Line, 
Figure 1. 
Plumage areas of a typical bird. 
I. Feet Fully Webbed—Two or three complete webs to each‘foot. 
A, Toes, four. 
a, Tarsus flattened. 
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.................-4- p. 48. 
