i i i ———_ — ~- ** 
ON THE TRACHEA OF THE GALLINZE, 499 
Fig. 28. Fig. 29. 
Front view. Back view. 
Numida cristata. 
fusiform, diminishing gradually as they aseend, until the last is quite 
minute. 
N. ptilorhyncha and N. rendalli are very similar. They agree with 
one another, and differ from N. cristata in that the extreme lateral 
edges of the penultimate and last tracheal rings meet and blend, 
thereby reducing the interannular interval to a guttate form, with the Page 376. 
apex directed outwards. In N. vultwrina there are as many as ten 
pairs of lateral tracheal fenestre. 
In Meleagris gallopavo the intrathoracic rings are all thinned away 
in front, whilst posteriorly they are not so, the consequence being that 
considerable interannular intervals separate them anteriorly, entirely 
absent posteriorly. The antepenultimate and penultimate rings are 
alone joined by a median anterior isthmus of eartilage. The former of 
these is split across behind ; the latter is not so, the fairly thick pes- 
sulus blending with the mid-posterior margin, its apex apparently pro- 
ducing a protrusion of its upper border between the sides of the fissure 
in the ring above. The penultimate ring is greater in diameter, and 
stronger than the rest. The last tracheal ring is represented only by the 
posterior extremities of the normal ring, its lateral and anterior parts 
having quite disappeared, in the half-grown, and perhaps even younger 
bird. It will be remembered that its lateral elements are much reduced 
in Lagopus. In Meleagris the reduction has gone further, the only 
remainder being the inverted blunt triangular cartilage that intervenes 
between the juxta-pessular margin of the penultimate ring and the 
posterior articulation of the first bronchial semiring on each side of 
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