Page 367. 
Page 368. 
490 ON THE TRACHEA OF THE GALLINA. 
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 con- 
solidated in the adult; the middle of the superior margin of which 
also articulates or blends with (according to the 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 direc- 
tion are parallel, which is not the case in Huplocamus. 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 con- 
siderable 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. 
Lagopus scoticus is not far different from Thawmalea in certain re- 
spects. The lower intrathoracic rings of the trachea are but little 
modified above the antepenultimate, there being slight median fusi- 
form anterior interannular intervals, whilst posteriorly the ununited 
rings are keyed together, as in the middle of the windpipe generally. 
The penultimate ring agrees with the same in Thaumalea, even to 
being incomplete behind, the free ends slightly receding from the ring 
above. The last ring anteriorly agrees with the same genus in detail, 
its lateral arched moieties being even more slender and delicate. 
Posteriorly, however, its ends develop into large fairly equilateral 
triangular expansions, continuous with the slender lateral arch at its 
supero-external angle, articulating with the posterior end of the first 
bronchial semiring at its inferior angle, whilst its supero-internal 
angle joins a similar development at the side of the pessulus, the 
hinder part of which expands into a sagittate cartilage, the blunted 
apex of which is directed upwards to meet the middle of the inferior 
margin of the antepenultimate ring of the trachea. The main bar of 
the pessulus is very slender; and all the structures under considera- 
tion are built up of a much more yielding cartilage (without ossifying 
tendencies) than in any non-tetraonine birds. The first and second 
bronchial semirings are parallel to one another in course throughout, 
and are more uptilted laterally than in Thawmalea. Posteriorly they 
are not expanded and scarcely touch; anteriorly they expand a little 
and articulate freely. The interannular intervals in essential points 
are not different from the.preceding genus. The bronchial semirings 
