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XXIX. An Account of certain Receptacles 
of Air , in Birds , which communicate 
with the Lungs , and are lodged both 
among the flefloy Parts and in the hollow 
Bones of thofe Animals . By John Hun* 
ter, F.R. S. 
Reekie, Feb. 27, y ■ 1 H E fingular communications 
1774 - which are found to fubfift, in 
birds, between the cavities of the lungs, and 
certain other cavities in the flefhy parts and 
in the bones, being peculiar to that tribe of 
animals, and having never yet been fufficiently 
explained, nor perhaps attended to, either by ana- 
tomifts or natural hiftorians j I imagine, that an ac- 
count of them will not be unacceptable to this fociety. 
It is not my prefent defign, to enter into minute 
deferiptions of all the particular communications of 
this fort, to be found in the diffe&ion of thefe ani- 
mals; but only to mention fuch general fails, as will be 
fufficient to introduce the fubjeit into natural hiftory, 
and ferve to open the enquiry into the final caufe. 
To make this matter more intelligible, 1 muff 
previoufly give an idea of the difference, between 
the particular cells in queflion, and thofe other cells 
of the cellular membrane, common to all animals ; 
and 
