30 PRACTICAL ORNITHOLOGY. 



in the order of complexity. Let us now see in what respects 

 they agree with, or differ from, those of the other orders which 

 I have described, namely, the Gemitores and Rasores. 



In Plate XII, Fig. 1 represents the trachea of the Wood 

 Pigeon, Columha Palumhus. In opening the skin of the throat, 

 we observe that the windpipe, in place of passing over to the 

 right side and returning, as in the Crows, Starlings, Thrushes, 

 and otlier Vagatores and Cantatores, keeps on the left side, and 

 indeed so far back that when the neck is bent, part of it becomes 

 higher than the vertebrae. And here I may venture upon a 

 general statement, which, however, I shall not dignify by giv- 

 ing it the name of a law : — In all birds of which the oesophagus 

 is funnel-shaped or tubular, the trachea passes along with it to 

 the right side ; in those in which there is a small dimidiate 

 crop, or slight dilatation, as the Deglubitores, it passes also to 

 the right ; and in all those which have a large crop, as the Gemi- 

 tores, Rasores, and Diurnal Raptores, it keeps to the left side. 

 On exposing the trachea of our Pigeon, we find that it is of 

 nearly uniform diameter, but much flattened, the anterior part of 

 its rings much broader and firmer than the posterior part, so 

 that the latter readily yields to the finger, and when dry falls 

 inwards with a concavity. The number of rings in this species 

 is an hundred and ten, and that of the bronchial half rings ten. 



Plate XII, Fig. 1, represents the tongue, a ; the j^rocesses 

 of the hyoid bone, h h ; the trachea viewed from before, c d e\ 

 the two thyro-hyoidei muscles, /: the lateral contractors g g^ 

 here terminated by the sterno-tracheales, g g ; the single pair 

 of muscles of the syrinx, li h ; the last ring of the trachea, e ; 

 and the two bronchi, i i. It is to be remarked that here the 

 muscular slip g, M'hich connects the trachea with the costal 

 process of the sternum on each side, is a direct continuation 

 of the contractor muscle, which was not the case in the Rook, 

 Blackbird, and Linnet ; that the muscles of the syrinx are 

 reduced to a single pair — and there are many birds in which 

 there are none at all, as we shall presently see ; that the last 

 ring of the trachea, e^ is very curiously modified, for in place 

 of being a solid bone, it is formed of an upper curved hoop, 

 a lower circular ring, and two connecting semi-cartilaginous 



