152 
INTRODUCTION. 
and perfecting one of the most important properties 
of vegetation. * 
The Nectariniadce, or Sun-birch , are placed by 
Mr. Swainson as the sub-typical family of the To- 
nuirostres or suctorial and slender-billed birds, of 
which the True Humming-birds stand as the most 
developed form. The five genera which the same 
gentleman has taken to represent the principle mo- 
difications of structure (1. Melithreptm, 2. Necta- 
rinia, 3. Anthreptes, 4. Ccereba , 5. Diceum) near- 
ly show' also their geographic distribution. The 
second or typical form is confined nearly to the 
tropics of the Old World, there holding the same 
rank in distribution as the more perfect Trockilidae. 
The first is confined to the islands of the Pacific 
Ocean, exhibiting a variety of the form there ; while 
the fourth, extremely limited in species, another 
family entirely almost occupying its place, is proper 
to America only, extending a very short way be- 
yond the boundary of the southern continent. The 
third, which shows only a stronger developed varia- 
tion of Nectarinia, is chiefly found in continental 
India, extending in small proportion to Africa ; 
while the fifth is intermediate between the third 
and fourth, both in form and in locality, the Aus- 
tralian islands being its more peculiar strong-hold. 
In the colouring of the group we find also a kind 
* Vaillant considers the Humming-birds and Sun-birds re- 
present, in their own class, the Bees and Butterflies among 
insects, performing, like them, the same services of impregna- 
