1888, ] NEW YORK ACADEMY OF SCIENCES. 99 
only quill showing emargination. In this the emargination is 
slight, and extends for only about two inches. If we remove 
the first primary, we have a wing in which the outer primary 
is the longest, the next succeeding primaries being each shorter 
than the one next in front, resulting in a long pointed wing, in 
which the primaries are narrowed toward the tip, and recede 
successively in length, giving the same form of wing we have 
in the man-of-war birds, in swallows, swifts, humming-birds, 
night-hawks, ete., in which there is never any emargination. 
Again, the emargination varies in extent, being limited in 
many birds to the first primary alone, and to the extreme apical 
portion of this; in others it occurs on the apical portion only, 
say for two to four inches of perhaps the outer four to six 
primaries ; while in very many birds, including the turkey buz- 
zard and its allies, and many hawks, it extends to the basal 
third or fourth of all the outer primaries. 
Having now shown that interlocking does not and cannot 
take place, it may be worth while further to point out that it is 
unnecessary. 
In a soaring bird, no great muscular tension is called into 
action. The large pectoral muscles, which move the wings up 
and down, are in a state of equilibrium, and under very slight 
tension, not more than are the muscles of a man’sarm when the 
arm isin au ordinary position of rest. The mechanism of the bony 
framework is such, as has been already shown, that the wing is 
kept extended in such a way that there can be only very slight 
strain on any of the numerous muscles of the wing itself. The 
extension of the primaries is automatically effected by the exten- 
sion of the wing, and results in no special strain, when once the 
wing is fully extended, upon any of the muscles whose function 
is to flex and extend the outer or phalangeal segments of the 
pinion. Hence the comparison made at the meeting of Decem- 
ber 12th, of a man’s arm held extended at aright angle to the 
body, in an unnatural position, with a bird’s wing held extended 
in soaring, in a perfectly natural position, was wholly irrele- 
vant. 
The hypothesis of the interlocking of the primaries during 
protracted soaring, to conserve energy and lessen fatigue, has 
not only no basis in fact, but is entirely gratuitous. 
DISCUSSION. 
Prov. TROWBRIDGE said that he still adhered to his belief in 
the rotation of the manus, and the interlocking of the tips of the 
first three or four primaries, and was confident that the orni- 
thologists would eventually admit it. 
