182 
ingly different, as to prove at once that 
there can be on identity whatever of the two 
species. TheWild Swanhas likewi se a small 
corneous spur a little arcuated and about 
half an inch in length placed at the extre- 
mity of the spurious or bastard wing. 
At the time the paper on the trachem 
of birds was published in the Linnaean 
Transacti ons, by Dr. Latham, it was not 
known that there were any sexual differ- 
ence in the formation of the trachea of 
this species. It has however been proved 
that there is a very great dissimilarity. 
In the female the windpipe after pass- 
ing down the whole length of the neck 
enters the keel of the sternum or breast- 
bone about two inches and a half or 
three inches at furthest, and then re- 
turns and enter the breast, to communicate 
with the Lungs. In the male, the trachea 
extends down the cavity of the keel, and 
afterwards enters the breast-bone, where 
there is no longer room at the posterior 
part of the keel, and there the flexure is 
constrained to change its direction froma 
vertical to a horizontal position, becoming 
