ee 
Ixxi 
cies, that is, two barbs proceeding from one quill; the barrel 
of the latter is small, and filled with pith, and the feathers are 
fine and hair-like. This, indeed, is the general character of 
the plumage of the struthiones. 
A few days after the death of one of these birds (a female), I 
carefully examined the sac, larynx, and trachea, and the follow- 
ing is an accurate account of the several appearances. The 
integuments covering the air-bag differ in no respect from the 
general investment of the neck ; beneath the skin is a strong 
and red muscular lamina, expanded over its sides and fore- 
part; the fibres are chiefly longitudinal, but several strong 
fasciculi run in different directions; the subjacent areolar 
_ tissue contains numerous nerves and vessels, especially veins. 
On opening the bag, the tracheal orifice (fig. 2) is seen dis- 
tinct and well-defined, of the form of a long parallelogram ; 
the mucous membrane of the tube is continued around its free 
margin, is reflected over, and adheres to the anterior and 
lateral parts of the tube considerably beyond the edges 
of the opening, and then expands in all directions to line 
this capacious reservoir, which is sufficiently large to con- 
tain at least a quart or three pints of fluid. This mem- 
brane is soft and vascular; numerous capillaries and large 
veins, with long tortuous nerves, are seen distinctly through 
it. The tracheal opening (fig. 4) is situated about three 
inches above the furculum, and in the middle line of the 
tube; it is two inches and a half long, and scarcely half an 
inch wide, but it can be easily extended to three inches 
in the vertical and to three-quarters of an inch in the transverse 
direction ; it is produced by a deficiency in the anterior part 
of six rings (in the two specimens I have examined the num- 
ber was the same); the cartilage above and that below the 
opening is broad and well defined; the extremities of the six 
lateral cartilages are sharp, thin, and very moveable; there is 
no dilatation, at least to any appreciable degree, in this part of 
the tube, and the rings are not all extended or continued into 
