376 



PROF. A. H. GARROD ON THE 



[Apr. 1, 



•with the apex directed outwards. In N. vulturina there are as 

 many as ten pairs of lateral tracheal fenestra. 



In Meleagris gal/opavo the intrathoracic rings are all thinned 

 away in front, whilst posteriorly they are not so, the consequence 

 being that considerable interannular intervals separate them ante- 

 riorly, entirely absent posteriorly. The antepenultimate and penul- 

 timate rings are alone joined by a median anterior isthmus of carti- 

 lage. The former of these is split across behind ; the latter is not 

 so, the fairly thick pessulus blending with the mid-posterior margin, 

 its apex apparently producing 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 



Fig. 30. 



Fig. 31. 



Front view. 



Meleagris gallopavo. 



Back view. 



normal ring, its lateral and anterior parts having quite disappeared, 

 in the half-grown, and perhaps even younger bird. It will be re- 

 membered 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 the organ. 

 A minute pointed process of the outer margin of the cartilage under 

 consideration indicates the situation of the posterior root of the 



