328 PAINTKD WARBLKKS. 



larged cut otthe syrinx of the Redstart. E. shows the right side of the syrinx and 

 the outside of the bronchial tube. W, is the windpipe where the cut end of the de- 

 scending tracheal muscle can be seen. A little below this muscle divides, and these 

 divisions reach their greatest development at a point opposite I, and between them 

 arise the two short bronchials ; above these, in the division of the broncho-lracheals, 

 arises the sterno-tracheal. Y. It will be seen that the lower, or posterior, ends of 

 both the broncho-tracheals and the bronchials are attached to the endsofihe two 

 upper half rings of the bronchial tube. V. The function of these muscles, thus at- 

 tached, is, when contracted, to draw forward the half rings, thereby tensitying the 

 tympaniform membranes to a greater or less degree (see Fig. 57, D, where is given a 

 greatly enlarged view of a section of the syrinx and a view of the inside of the left 

 bronchial tube, L, being the tympaniform membrane) then the air is expelled forci- 

 bly from the lungs (see ib,, II) causing this tensifieti membrane to vibrate; thus pro- 

 ducing sound. But the high, shrill song of the Redotart is not prodused by the vi- 

 bration of this comparatively broad membrane, but by the small semiluna, ib., X, 

 which rests on the transverse bone, T. The broncho-tracheals are also attached to 

 the ends of this bone, and by rotating it the narrow and thin semiluna membrane 

 is twasted and tensified in various portions, while the air rushing past it from both 

 bronchial tubes causes it to vibrate, thus producing the song. The song is, howev- 

 er, probably somewhat modified by the windpipe, which can be tensified to some 

 extent by the action of the tracheal muscles extending down its sides, and to assist this 

 tension the bird raises its head as it sings, thus drawing up the windpipe. Compare 

 the cuts mentioned above with Fig. 7, page 4, B and C. and with Fig. 36, page 61, E 

 and F, and it will be seen that the Redstart does not differ from other warblers in 

 syringeal structure: it is, in fact, clearly a member of the great order of Singing Per- 

 chers. 



If we now examine the syrinx of a member of the order of Songless I'erchers 

 we shall see that the tracheal muscles in descending the windpipe toward the syrinx 

 do not divide, as in the Redstart and all other Singing Perchers, to form the broncho- 

 tracheals, but remain single and become the stcrno-tracheals ( see Fig. 57, C, side 

 view of the syrinx of the Wood Pewee, greatly enlarged ; Y, is the sterno-trachealis), 

 while the only other syringeal muscle is short and broad (see ib. I) and adheres all 

 along the upper portion of the first half ring of the bronchial tube, ib. V. At B, is 

 given a section of the sjrrinx and of the inside of the left bronchial tube. The tym- 

 paniform membrane, L, extends the entire length of the tube, but although the 

 transverse bone is present, it does not bear a semiluna membrane; hence it can be 

 seen that all of the sounds that the Wood Pewee is capable of uttering must be pro- 

 duced by the vibrations of the comparatively broad tympaniforms. Sounds produced 

 by a broad membrane are lower in musical scale than are those made by one more 

 narrow. Hence all of the notes of this flycatcher, even the softly-given, chattering 

 attempt at a song, are in a minor tone. 



The gullet and proventriculus of the Redstart do not differ in any perceptible 

 degree from those of other warblers. The stomach is of medium size, a little lar- 

 ger than that of the Yellow Warbler (see Fig. 36, page 61, S and C, and compare 

 with Fig 56, U) but is smaller than that of the Chestnut-sided (see Fig. 36, page 61, 

 H and I). The walls of the stomach of the Redstart are thicker than in the Yellow- 

 but not as muscular as in the Chestnut-sided (see Fig. 56, U, and compare with Fig. 



