OCR Text |
Show 366 PROF. A. H. GARROD ON THE [Apr. 1, the continuity of the lower edge of the antepenultimate ring to a extent. The last tracheal ring is characterized by the great obliquity of the plane of each of its lateral moieties, the downturned angle between which is less than 45°. Behind there is a considerable interval between its downward-directed ends, filled up by the pessulus, which is prevented from touching them by the intrusion of the extremities of the similar parts of the, also incomplete, penultimate ring. In front the middle of the ring is expanded into a large, quadrilateral, square-set cartilage, ossified in the adult, from the superior angles of which the slender oblique side elements of the ring take origin, to the inferior angles of which the first bronchial semiring is articulated in the chick and consolidated in the adult; Fig. 15. Fig. 16. Front view. Back view. Thaumalea picta. tbe middle of the superior margin of which also articulates or blends with (according to tbe age) the broad median descending process of the penultimate ring. The first and second bronchial semirings are much alike ; both are slightly swollen at their extremities, especially the anterior; and their planes of direction are parallel, which is not the case in Euplocamus. The lateral intervals between the penultimate and last tracheal rings are like the section of a plano-concave lens with the concavity (formed as it is by the arch of the lateral moiety of the last ring) downwards. The interval between the last ring and the first bronchial semiring is considerable and broadly fusiform ; that between the first and second semiring is narrow and lanceolate, or fusiform in the adult, where the two semirings consolidate at their extremities. |