AND BLACK-BILLED AUK. 
11 
able, are to him prompt and certain grounds of distinction. 
With what superior facilities to the northern naturalist 
would a native of the tropical regions enter on the descrip- 
tion of his indigenous animals, that, for example, of the 
numerous species of birds of paradise, of humming-birds, 
parrots, monkeys, insects ? and the tropical zoologist would 
find a difficulty of a similar kind, though not so extensive, 
in describing our northern animals. 
To these causes are mainly to be ascribed much of the 
difficulty and error which we meet with in the study of 
zoology, as well as to the immense diversity of its objects ; 
and much requires yet to be supplied, even in one of its 
most interesting and apparently most accessible branches, 
Ornithology. 
Our knowledge of many species of European birds is still 
sufficiently defective ; and from their being more frequent- 
ly presented to our observation, and naturally furnishing 
criterions of distinction for others, they especially require 
to be clearly known. 
In the notices of a few of those species that have occa- 
sionally been submitted to the attention of the Society, I 
have felt the influence of the preceding views, and have 
uniformly communicated only the result of my own obser- 
vations, in the first instance. 
When I found opinions of others on the same subjects, 
whether favourable or opposed to my own, I have freely 
examined them ; but have not allowed myself to enter into 
discussions in regard to all the speculations that have been 
advanced, as these add but little to the value of ornitholo- 
gical investigation. 
I shall have the honour of continuing this series of ob- 
servations which I have commenced on several northern 
animals, regarding which obscure notions may still be en- 
tertained ; and those to which I shall confine my attention 
