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fqueezed together with the finger and thumb : 
however, the bones of the extremities have very 
folid Tides. 6thly, the paffage by which the air 
gets into the bones can be eafily perceived, even in 
cleaned bones. Generally there are feveral holes, 
placed together, near the end of the bone which is 
-next the trunk of the bird ; and diflinguilhable, by 
having their external edges rounded off ; which is 
not the cafe with thofe holes, through which either 
nerves or blood veffels pafs, into the fubftance of the 
bone. 
I muff next give an idea of the mechanifm of 
the lungs in birds, which renders them fit for com- 
municating air to the above defcribed parts. This 
confifts principally in certain connexions. 
It has been afferted, that birds have no diaphragm; 
but this opinion muff have arifen either from a want 
of obfervation, or from too confined an idea of a 
diaphragm ; for there is a pretty ffrong, but thin 
and tranfparent, membrane, which covers the lower 
furface of the lungs, and adheres to them ; this 
membrane gives iniertion to feveral thin mufcles, 
which arife from the inner furfaces of the ribs. 
The life of this part is to leffen the concavity of 
the lungs towards the abdomen , at the time of in- 
fpiration ; and thereby to affiff in dilating the air- 
cells ; for which reafon, it is to be considered as 
anlwering one main purpofe of a diaphragm. 
Befides this attachment of the lungs to the dia- 
phragm, they are alfo conne&ed to the ribs and 
Tides of the vertebra, 
Thefe adhefions are peculiar to this tribe of ani- 
mals j and are of fingular ufe, or rather of abfo- 
lutc 
