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XV. Observations on the Trachee of Birds; with Descriptions 
and Representations of several not hitherto figured. By William 
Yarrell, Esq., F.L.S. 
Read February 6, 1827. 
Tue various qualities and powers of voice exhibited by birds 
in general, and the diversity of structure known to exist in the 
tracheæ or windpipes of different species in some particular 
families, have justly excited the attention and remarks of several 
writers. Dr. Latham, in the 4th volume of the Transactions of 
this Society, has furnished descriptions and illustrations of the 
peculiarities of this part in some of those species most remark- 
able for their deviation from the common form ; and to his paper 
I shall occasionally take the Liberty. to refer. 
not included in the essay before mentioned: and the Droit 
communication, accompanied by drawings of several tracheæ 
not hitherto figured, will, I trust, be considered an acceptable 
addition on this interesting subject. - 
The peculiarities in the form, as well as in the eat bodition; of 
the several parts of the windpipes of birds, having already been 
described under the different names of the glottis, or superior 
larynx; the tube; the bone of divarication, with its cross-bone 
forming the lower end of the tube; and lastly, the bronchia, by 
which the bone of divarication is connected with the lungs ;—I 
shall proceed at once to the descriptions of those new forms of 
tracheæ which are the subject of the present communication. 
The 
