AMERICAN WARBLERS. 



127 



treminal tliird of the tongue /'see Tig. 56, V). In the tongue of the Flycatchers as 

 typified by that of the Wood Pewee, there are no bristles at rhe tip, but a kind of 

 forked, horny appendage that is evidently produced from behind as fast as it wears 

 away at the tip. 



Fig. 57 



Least Flycatcher:- H, upper niarniible; B, iuside left bronchial tube; C, right side ol syrinx 

 and outside of right bronchial tube. lisDsTART :- D, inside of left bronchial tube; E. syrinx and out- 

 side of right bronchial tube. Wood Pewee :- F, tip of tongue. All Figures ;- w, trachea; y, sterno- 

 tracheal ; I, broneho-tracheals; v, transversa bone; x, seniiluna membrane; l, tympaniform mem- 

 brane; u, bronchial tube ; 11, lung. All figures, excepting A, much enlarged 



The trachea is a straight, rounded cylinder ; neither it nor the larynx differ 

 to any noticeable degree from those of other warblers. 



The long tracheal muscles, beginning at the laryn.v, descend the trachea until 

 they reach a point a little above the syrinx where they divide to become thebroncho- 

 tracheal vocal muscles. Between these muscles, and consequently below their divi- 

 sion, emerges the sterno-tracheal, and below this the small bronchials of which there 

 are two pairs, one on each side of the syrinx. The bronchial tubes are each made up 

 of fourteen rings, half of which are complete, that is they extend wholly around the 

 tube, but the other seven are incomplete or half-rings. The spaces on the tubes thus 

 left incomplete by the half-rings are occupied by thin, transparent membranes; the 

 tympaniforms. Above the tympaniforms is a single thin bone to which they are at- 

 tached. This bone crosses the windpipe from front to back and is called 'the trans- 

 verse bone. On the upper part of this bone, projecting into the windpipe, thus stand- 

 ing upright between the entrances to the bronchial tube is a very thin, and very 

 slight membrane; the semiluna. At Fig. 57, D and E, I have given a greatly en- 



