BEE-EATERS AND SWALLOWS. 13 
The Swift (^C^pselus) is one of the fastest flying 
birds, and also of long-con- 
tinued flight. The sternal 
apparatus is represented in 
the engraving, which shows 
also its full, natural size. 
The keel, it will be observed, 
is much elevated and pointed at the anterior angle, and 
as no particular strength is required in the clavicles 
and furcal bone, on account of the easy flight of the 
bird, those bones are slight in comparison with the 
corresponding portion of the anatomy of the Falcon, 
which is likewise a bird of rapid flight, but one that 
requires great strength in these parts to support the 
stress which the powerful action of the muscles in its 
momentary rush would impose upon those bones. The 
sternum of the Falcon is much firmer and more deve- 
loped in the anterior part ; it is shorter in comparison, 
narrower in the posterior part than in the anterior, and 
the posterior angles are perforated with holes. That 
of the Swift has the posterior part broadest, and the 
angles have no holes. In the sternum of the Swift, 
observes Mr. Mudie, we have the maximum develop- 
ment of that bone as a carrying basket in the air, but 
still accompanied with considerable power of wing, 
though the Swift never rushes, either by its power of 
flight or by a momentum of gravitation, like the eagle. 
Its sternum bears up the whole under part of the 
body, and thus it can remain longer on the wing with- 
out fatigue than any other bird with which we are 
familiar.* 
* Natural History of Birds. 
