47 
rho fnrculnm (consisting of the clavicles anchylosed together at 
thoir mesial extremities,) the coracoid hones and scapulars, all con- 
verge on eitlier side at the shoulder, and form the point of articu- 
ation for the hones of the wings ; the furculum acts as a sprin<^ to 
prevent the wmgs from striking too far up or down, ami thus 
apping against each other, above the back or under the belly • 
the coracoid bones are stays to the force of the pectoral muscles,' 
and the scapulars, imbedded in the muscles of the back, tend to 
brace the dorsal and sternal portions of the skeleton together witli 
irmness and elasticity. The bones of the wing are the same as 
those of oim own arm ami hand, with some modification, and the 
action of the elbow-joint, being only in one direction, when tlie 
wing IS extended, it presents an inflexible surface during the down- 
wanl stroke. To the bones correspomling to our hand, the prima- 
ries, or gi-eat quill-feaUiers are attached ; to the fore-arm (ulna and 
r.ulius) the secondaries and wing coverts, and the tertials and 
scapulars to the larger bone or humerus. I will not stop to speak 
of the beauty of form and structure of the feathers with which 
his wing IS furnished, except so far as is necessary in endeavouring 
to show how this wonderful apparatus is made available for the 
purpose for winch it was constructed. 
1 ho front part of the wing, that first presented to the air in 
forward flight, is stiff and unyielding, well adapted for cutting its 
way t irough the air— at the extremity of the wing are placed the 
large quil -feathers, or primaries ; they are very strong and rigi.l, 
and bear the chief burden of the flight; the other feathers become 
weaker and more pliable, as they are placed nearer to the body of 
the bird, each feather strongest at the point of insertion, and be- 
coming more and more yielding towards its extremity ; the whole 
so set as to be parallel with the body of the bird when flyin^. the 
points directed to the rear. Tliese feathers, which are divided into 
two portions by a nearly central shaft, overlap each other, the 
anterior web, which is the stronger and stiffer, being uppermost • 
when, therefore, the down-stroke is delivered, the wing presents to 
the air beneath it an impenetrable and unyielding surface, but 
when the corresponding up-stroke is ma.le the yielding posterior 
web of each feather becomes depressed by the resistance of the air 
above, thus seiiarating the feathers so as to allow of the free passa-c 
ot the air— by this means giving the maximum amount of force to 
