16 
life is less developed, and a greater number later in the season when 
the supply of insect food has become more abundant. I have also 
some reason to believe that the young of many species breed during 
the first season, for among others I frequently found one section of 
the Honey-eaters (the Melithrepti ) sitting upon eggs while still 
clothed in the brown dress of immaturity; and we know that such is 
the case with the introduced Gallinacece , , three or four generations 
of which have been often produced in the course of a year. 
Another peculiar feature connected with the Australian ornitho- 
logy is that of its comprising several forms endowed with the power 
of sustaining and enjoying life without a supply of water, that ele- 
ment without which most others languish and die; for instance, the 
Halcyons, which I found sustaining life and breeding on the parched 
plains of the interior during the severe drought of 1838-9, far re- 
moved from any water ; the food of these birds being insects and 
lizards. 
A considerable number of the older-known of the Australian birds 
have been described in the general works of Vieillot, Latham, Shaw 
and others ; but their descriptions are so vague, and the species them- 
selves referred so frequently to genera widely different from those to 
which they really belong, that it has been impossible to identify the 
whole of them with certainty; wherever this could be done their 
names have been adopted, or quoted in the synonyms. 
The “ Birds of Europe” were arranged according to the views of the 
late Mr. Vigors; and in the “Birds of Australia” the arrangement 
is mainly the same, with some modifications of my own which ap- 
peared to me to be necessary. 
I have been constrained, for the sake of uniformity in size, to 
divide the present work into seven volumes; the first of which 
comprises the Raptores, the small number of which will account for 
its being somewhat thinner than the others; the second, third, 
fourth, fifth and sixth volumes comprise the Insessores, Rasores and 
Grallatores in one continuous series, and the seventh the Natatores. 
The following synoptical table will give a general view of the 
whole; it contains all the additional information I have received, or 
been able to procure, during the progress of the work ; the charac- 
ters of the new genera I have found it necessary to institute, &c. ; 
and the references to the volumes in which the respective plates are 
arranged will render it easy to consult and to quote them. 
Order RAPTORES. 
Family FALCONID./E. 
Subfamily AQUILINAS. 
Genus Aquila. 
Numerous species of this genus exist in Asia and Europe ; the 
form also occurs in Africa, and in North America ; so far as I am 
