1879.] 



TRACHEA OF THE GALLING. 



355 



that anteriorly it is slightly hent downwards in the middle line, to 

 assist in the changes of form connected with the bifurcation of the 

 tube. The penultimate ring, from its position, is more pronounced 

 in this respect, whilst posteriorly the pessulus runs up to blend with 

 it, not at its inferior margin, but by a wedge-shaped cartilaginous 

 expansion, the apex of which touches the lower margin of the ring 

 above. That this is so is proved by the existence of two oblique 

 indented lines, one on each side, converging superiorly, where they 

 nearly meet to form the apex of the just-mentioned wedge. The 

 last tracheal ring anteriorly sends down an obtuse median process, 

 the inferior margin of which constitutes the summit of the notch 



Fig. 1. 



Fig. 2. 



Front view. Back view. 



Pavo spicifer (adult). 



N.B. — This and all the subsequent diagrams are drawn to one scale, and have 

 no relation to the actual size of the structures. 



between the divaricating bronchi, whilst its posterior surface forms 

 the anterior attachment of the pessulus. Posteriorly this ring is 

 incomplete, the two obliquely truncated ends being separated by a 

 considerable interval occupied by the pessulus in the middle line, 

 and laterally by the commencement of the membranous inner walls 

 of the bronchi. 



In the middle of the upper border of the penultimate ring an- 

 teriorly a white line is seen sending a limb down on either side, 

 beyond the ring itself, onto the next, at the lower margin of which 

 it ceases at the root of the obtuse median process. Such an ap- 

 pearance indicates that in the older bird fusion of the two rings will 

 occur at the spot, as an inspection of the part in the adult verifies. 

 From the above description it will be also seen that the pessulus— 

 a slender cylindroid bar, expanded and flattened at each end — is 

 anteriorly attached to the last, and posteriorly to the penultimate 



23* 



