“Tree-Ducks” of the genus Dendrocygna. 29 
5th Edition of the “Key to North American Birds” by Dr. ELLiorr 
Covzs (p. 207—213), which is illustrated by MaccızLıvray and 
myself. 
I have also given descriptions of these parts in many of the 
Anseres in my “Osteology of Birds” (in: N. Y. State Mus.), in a 
section entitled Modifications of the Larynx and Trachea among the 
Ducks (p. 297—301, illustrated). 
I have examined the ossifications which take place in the struc- 
ture of the respiratory and vocal organs of male and female spe- 
ceimens of Dendrocygna bicolor and D. autumnalis, and I find that 
they are of the more simple arrangement as they occeur in many of 
the ordinary ducks, as for example Anas platyrhynchos and others. 
As the material examined by me in this regard had been salted 
and dried for partial preservation during transportation, I could 
not make as satisfactory examinations as I should have wished. 
Still, I have before me at this writing the entire trachea, in- 
eluding its extremities, of a specimen of Dendrocygna bicolor (457), 
and it is ample to prove the correctness of the statement just made. 
Owen has given us an excellent chapter on the “Air-passages 
in Birds”, in which he presents a figure of the tracheal coils and 
lower larynx of Bewick’s Swan, and three different views of the 
lower larynx of Mergus serrator.') 
Eyron gives us no descriptions of these parts in his Osteologia 
Avium; but as to whether he does or not in his more formal work 
on the Anatidae, I am not prepared to say, as that volume is 
not to be found in the libraries of the city of Washington, which 
it certainly should be. 
Remainder of the axial skeleton in Dendrocygna. 
Under this heading there will be considered the vertebral 
column, the ribs, the sternum, and the pelvis of the “Tree- 
Ducks”, the same being made comparative as far as necessary. After 
these have been treated, I shall pass some observations on the 
pectoral arch or shouldergirdle of the forms under consideration, 
completing the comparative account with descriptions of the bones 
of the pectoral and pelvic limbs. In my “Osteology of Birds”, pre- 
viously cited, I present a very full description of the osteology of 
l) Owen, RICHARD, Comp. Anat. and Physiol. of Vertebrates 
(Vol. 2, p. 217—225). 
