26 PRACTICAL ORNITHOLOGY. 



rings, Fig. 13, a a, is larger than the rest, and has its inferior 

 margin thickened and curved, so as to come to a point before and 

 behind, as at b. If we remove the bronchi, Fig. 1, r r, from 

 this ring, Fig. 13, a ah, and look to it from beneath, we find 

 that it is divided by a narrow bony slip into two semicircular 

 portions, forming the entrances of the bronchi, Fig. 14. Fig. 

 15 shews the appearance of the bifurcation from beneath, the 

 bronchi being stretched out laterally ; the dimidiating slip of 

 the last entire ring of the trachea, a ; the two last or dimidiate 

 rings of the trachea, h h ; the lower surface of the bronchi, c c, 

 formed of elastic membrane ; and lastly, two roundish, subcar- 

 tilaginous bodies, with the use of which I am not acquainted. 

 We have now to examine the syrinx, or inferior larynx, with 

 reference to its muscular apparatus. 



Viewed anteriorly, as in Fig. 1, the syrinx^ q, represents 

 two small pads of muscles, together with two very slender mus- 

 cular slips ; but these muscles are much more distinctly seen 

 in the lateral view, Fig. 16. There are four pairs. 



1. The internal anterior muscle of the syrinx, a, arises from 

 several of the lower rings of the trachea, and is inserted into the 

 anterior extremity of the first half ring of the trachea. Its action 

 must be to widen the syrinx in its antero-posterior diameter. 



2. The external anterior muscle, h, arises in the same 

 manner, on the outer side of the last, and is inserted into the 

 anterior extremity of the second or last half ring of the trachea. 



3. The posterior muscle, c, arises behind the last two, and 

 is inserted into the hind part of the last tracheal half ring. 



4. Between the last two is seen a shorter, broader, and 

 thinner muscle, d, which arises from a few of the lower rings 

 of the trachea, and is inserted into the whole upper edge of the 

 last tracheal half ring. 



These muscles acting conjointly must elevate the last tra- 

 cheal rings, and elongate the bronchi ; acting separately, they 

 must elevate either extremity of the former. 



The last muscle, g, the sterno-trachealis, is a slip, which arises 

 from a ring of the trachea, between the two anterior muscles, 

 passes backwards and downwards, and is inserted into the an- 

 terior part of the costal process of the sternum. Its action is 



