192 : BIRDS

three divisions on which naturalists are agreed, the
other differences between birds being really so slight,
and the series of intermediate forms so involved, that
almost every ornithologist has a way of his own in
regard to them.

These classifications mostly depend on the presence
of several peculiarities in the bird, some of them

 

PARTS OF A BIRD

structural and most of them external. To assist the
reader in following them, we have here a bird marked
out so as to show a few of the external features of
importance. Here 1 is the beak, the upper edge
being the ‘ culmen,’ the lower half being the mandible ;
2 is the ‘crown, the space between it and the beak