EXTERNAL ANATOMY. WING FEATHERS. 87 
the tenth, is longer than any of the secondaries, and in 
the giant humming-bird the secondary and tertiary 
quiUs consist altogether of only six feathers ; the ter- 
tials, in fact, may be termed as altogether obsolete. Per- 
haps the most correct definition of the different powers 
of flight in these two groups would be this, that the 
swallows have the strongest, and the humming-birds, 
while their flight lasts, the most rapid. The wing of 
the giant humming-bird seems to be composed entirely 
of prim.ary quills, gradually, but regularly, diminishing 
in size from the tip to the very end of the scapulars. 
The exterior quill, although very strong, and much 
more curved than the others, is, nevertheless, not very 
typical of a falcated wing. The white-tailed black 
species* is much more so, but the sickle-winged hum- 
ming-birds (^ fig. 43.) are in this respect pre-eminent, for 
not only are the three outer feathers greatly curved, but 
their quills are unusually strong, dilated, and flattened : 
there must be something very j)eculiar in the flight of 
these latter, of which, at present, we are quite ignor- 
ant. 
(80.) III. Pointed wings come nearest to those 
which are more particularly termed acuminated, and 
the passage from one to the other is marked by nume- 
rous gradations, almost too refined for popular compre- 
hension. Pointed wings may be divided under two sorts. 
In the first, the outermost quiU is either the longest, 
or is nearly equal to the next one or two, but the 
secondaries and tertials are of the ordinary length; that 
is, they are two thirds as long as the primaries. This 
is the leading distinction of the American genera Syl- 
vicola, Se.tophaga, and Se’ivrus.f A slight variation 
from this proportion in the primaries is seen in the 
parrots. In that common, but most beautiful, species 
the Trichogloftsus Swainsoni |, the first quill may be still 
eaUed as long as any of the others, although the second 
• Trochitus niger, Zool. 111. vol. i. pi. 82. 
t Nortll. Zool. vol. 11. p. 203. 
j Jardine and Selby, vol. ii. pi. 111. See also Zool. HI. vol. i». pl* ia. 
G 4 
