OCR Text |
Show 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 fenestrae. 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 cartilage. 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. Back Tiew. Meleagris gallopavo. 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 the organ. A minute pointed process of the outer margin of the cartilage under consideration indicates the situation of the posterior root of the |