INTRODUCTION. 7 
The shape and size of the bill vary greatly, as will be seen by the following 
illustrations representing fifteen of the principal types among our birds : — 
Sill of Humming-bird a’ 
Bill of Whippoorwill 
Bill of Least Bittern Bill of Duck 
Bill of Song Sparrow 
~ 
: 
a 
Bill of Warbler 
Bill of Flamingo 
= 
alle 
yas 
7a Bill of Woodpecker 
Bill of Heron 
Cere. A membrane (usually hard), which covers the base of the upper mandible. 
(Hawks, Parrots, Jeegers. ) 
Nasal Fossa, or Nasal Groove. Groove in which the nostrils open. 
Gonys. Lower outline (middle) of the under mandible, A to B. 
Culmen. The ridge of the upper mandible. 
Unguis. The nail on the end of the upper mandible. Very pronounced in some 
families of Water Birds, — Ducks, Pelicans, and Petrels. 
Mandibles. — Some authors use the word mavilla for the upper half of the bill, and 
mandible, for the lower. I prefer, however, to describe the two halves of the bill 
as upper and lower mandible. 
