Note 11 — INTRODUCTION.

A polymorphic group, perfectly distinguished from Passeres by the above characters in which, for the most part, it approximates to one or another of the following lower groups, from which, severally, it is distinguished by the inapplicability of the characters noted beyond. My divisions of Picariæ correspond respectively to the Cypselomorphæ, Coccygomorphæ, and Celeomorphæ of Huxley, from whom many of the characters are borrowed.