BIRDS. 
O 
posterior angles, and is long in proportion to its width, 
and considerably broader in the rear than towards the 
front. The furcal bone is, proportionately, weaker 
than the other parts, and is not so perfect in the arch 
as that of the Swift. This is tlie sternal apparatus of 
a bird that feeds upon the wing, but has not the long- 
sustained forward flight of the Swift. It is merely 
required to support the bird and its muscular efforts, 
as it darts from flower to flower, or remains suspended 
on the wing in quest of food. The wings have a greater 
resemblance to those of tlie Swift, than of any ocher 
bird. They are remarkably long and narrow, reaching 
often beyond the limit of the tail feathers. Tlie exte- 
rior outline of the wing is very much curved, and the 
first quill is always the longest, the other primaries 
gradually shortening. The secondary quills are gene- 
rally very short, and the coverts are smooth and close 
set. The shafts of the quills are always very strong 
and elastic ; and in some of the species the basal part 
of the shaft is so much enlarged, that its diameter 
nearly equals the breadth of the inner web. The webs 
are firmly united together and extremely compact, so 
as to form a substance almost like a thin plate of 
wdialebone, and by reason of their strong resistance to 
