202 



GENERAL ORNITHOLOGY. 



Fifi 97. — 1, 2, left hand, two tracheal rings, sepa- 

 rate, as in fig. 96, b; 1, 2, right hand, the same put 

 together, as in fig. 96, a. (After MacgilUvray. ) 



partly over each other on alternate sides is something lilce that upon which a cooper fastens 

 the ends of any one barrel-hoop without any nailing or tying. The rings are in some birds 



perfectly cartilaginous : in most they become 

 osseous. The trachea is moved by lateral 

 muscles, which not only shorten the tube by 

 approximating the rings, but also drag the 

 whole structure backward, by their attach- 

 ment to the clavicle and sternum. The strip, 

 or two strips, of muscle lying upon each side 

 of the trachea, is the contractor trachece (fig. 

 101, 1, ss, ss) ; the most anterior, when there 

 are two, as soon as it leaves the tube to go to the clavicle, becomes the cleido-trachealis, or 

 cleido-hyoid, fig. 101, l, /, /; the other is similarly the sterno-trachealis. The latter may be a 

 direct continuation of the contractor, as in fig. 101, i, the loose strips under q, or apparently 

 arise separately from the side of the lower end of the tube, as in fig. 101, ^^, e. (Other muscles 

 are to be described with the larynx superior and inferior.) The trachea is long in birds, pro- 

 portionate to the extension of the neck ; it is very flexuous, following with ease the bends of 

 the neck in which it lies so loosely. Its cross section is oval or circular ; but all that relates 

 to the configuration and course of the pipe requires special description, — so variable is the 

 organ in difterent birds. It is subject to dilatations and contractions in any part of its extent, 

 and to deviations from its usual direct course to the lungs. Minor modifications must be 

 passed over. The most remarkable expansions of the lower part of the tube occur in many 

 sea-ducks and mergansers {Fuligulince and Mergince), and some other birds; several lower rings 

 of the trachea being enormously enlarged and welded together into a great bony and mem- 

 branous box, of whoUy irregular, unsymmetrical contour. Such a structure, represented in 



figs. 3 and 98, is termed a tracheal tympanum, or lahi)- 

 rinth. It is not a part of the voice-organ proper, but 

 may act as a reverberatory chamber to increase the vol- 

 ume of the sound, without however modulating it. Being 

 chiefly developed in the male, it is a kind of secondary 

 sexual organ. The vagaries of the wind-pipe are still 

 more remarkable. Very generally, in cranes and swans, 

 the trachea enters the keel of the sternum, which is exca- 

 vated to receive it, and where it forms one or more coils 

 before emerging to pass to the lungs. This curious wind- 

 ing is carried to an extreme in our Grus americana, the 

 whooping crane, in which the wind-pipe is about as long 

 as the whole bird, and about half of it — over two feet of 

 it! — is coiled away in the breast-bone (fig. 99). The 

 same thing occurs in G. canadensis to a less extent (fig. 

 100). In a Guinea-fowl, Gutter a cristata, a loop of the 

 trachea is received in a cup formed by the apex of tlie 

 clavicles. In various birds, as some of the curassows {Cra- 

 cidai), the capercaillie (Tetrao urogallus), a goose, Anseranas semipahnata, and the female of the 

 curious snipe, Rlujnchcea australis, the trachea folds between the pectoral muscles and the skin. 



Fig. 98. — Bony labyrinth at the bot- 

 tom of the trachea of the male of Clangula 

 islandica, seen from behind, nat. size. Dr. 

 R. W. Shufeldt, U. S. A. 



The Larynx (the Gr. name, \apvy^, larugx) is the peculiarly modified upper end of the 

 trachea ifig. 101, 1, and 3 to 12). In mammals it is a complicated voice-organ, containing the 

 vocal chords and other consonantal apparatus; in birds the construction is simpler, as the 

 larynx merely modulates the sound already produced in the lower end of the tube. It lies in 



