EXTERJfAI. ANATOMY. WING FEATHERS. 83 
quality through almost every one of the minor groups 
of the perching birds. Taking the other extreme of 
slowness, we find that all birds belonging to or repre- 
senting the rasorial order, have the shortest wings, and 
consequently the most imperfect flight. Not to mention 
our domestic poultry, induding the fowl, Guinea hen, 
turkey, and peacock, there is the whole of tlie ostrich 
family, to whom the power of lifting their heavy bodies 
from the earth is altogether denied. Hetween these two 
orders, or primary types, stonds the grallatorial, which, 
in this respect, is not greatly inferior to the aquatic, but 
yet vastly superior to the rasorial. We accordingly find 
that its prototype among the perchers, which is the 
tenuirostral tribe, is only inferior to the sw'allows. A 
humming-bird, indeed, appears to fly with greater 
swiftness than it really does, because, from its very 
diminutive size, the eye no sooner discerns it than it 
disappears ; but this, in some measure, may be the effect 
of size, more than of pre-eminent rapiclity in flight. 
Admitting, however, that a humming-bird passes 
through the air even with greater celerity than a 
swallow, they differ materiidly in the power of sustain. 
flight- The one can remain on the wing for hours, 
while the other, after probing the tubes of a flowering 
shrub, generally perches upon one of its naked twigs, 
for the obvious purpose of rest. In the two remaining 
orders of birds, the powers of flight are very unequal. 
In the raptoren, which immediately follow the natatore.s, 
we accordingly find this faculty considerably developed; 
for of all land birds, excepting, perhaps, tlie swallows, 
none are so swift or vigorous on the wing as the eagles 
and falcons. Lastly, we have the insessorial or perch- 
ing order, where the flight is only moderate : it is less 
rapid, indeed, than that of the raptores; but more per- 
fect than in the raxores. These facts lead to a very 
curious result ; for they establish a circular series in the 
development of that faculty most characteristic of the 
whole class. The maximum of flight is found in the 
natatorial order, from which it branches off^ as it were, 
G £ 
