28 PRACTICAL ORNITHOLOGY. 



Let us now compare with these organs in the Rook, the cor- 

 responding parts in the Blackbird, referring again to Plate X. 



The trachea itself, Fig. 2, a b, is in no essential respect 

 diiferent from that of the Rook, it being a little flattened, and 

 slightly tapering, its rings complete and about eighty-two in 

 number. The larynx also is similar, and presents the same 

 muscles similarly arranged. 



Fig. 3 represents the tongue, a, covered with a horny en- 

 velope, which is fringed towards the end ; the two crura of the 

 hyoid bone with their muscles, b b ; the elastic ligament, c; 

 connecting the larynx with the base of the hyoid bone ; be- 

 hind which are the thyro-hyoid muscles ; the aperture of the 

 glottis, c?, the upper rings of the trachea, e ; the cleido-thyroid 

 muscles, yy*; and the contractors of the trachea, g g. 



Fig. 4 shews the bones of the larynx, namely, the thyroid, 

 with its appendages, the cricoid, and the two arytenoid, to- 

 gether with the thyro-cricoidei postici, and the arytenoidei. 



Fig. 5 exhibits the thyro-arytenoideus, which opens the rima 

 glottidis ; and Fig. 6, the thyro-cricoidei, which aid in closing 

 it, and bring the parts forwards. 



At the bifurcation of the trachea, we find precisely the same 

 arrangement as in the rook. The lower ring is larger, and 

 divided at its lower pointed margin into two passages for the 

 bronchi, as is seen in Figs. 7 and 8. The muscles of this part, 

 viewed anteriorly, are seen in Fig. 2, in which b b mark the 

 cleido-thyroid muscles ; c e^ the contractors of the trachea ; 

 d d, very slender muscular filaments attached to the sternum ; 

 b, the syrinx, with its muscles ; e e, the sterno-tracheales ; and 

 ff, the bronchi. Viewed laterally. Fig. 9, the muscles are 

 seen to be similar in number and arrangement to those of the 

 Rook ; namely, the anterior internal muscle, a, arising from 

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

 anterior extremity of the first half ring ; the external anterior 

 muscle, arising in the same manner, on the outer side, and 

 inserted into the anterior extremity of the last half ring of the 

 trachea ; the posterior muscle, arising behind the last two, and 

 inserted into the posterior extremity of the last half ring ; the 

 intermediate broad muscle, inserted into the upper edge of the 



