FAMILY CHARACTERS. 7 



Below the transverse bone, in the interspaces caused by the 

 interruption of the bronchial half rings are v-shaped mem- 

 branes which stretch from side to side of the ends of the half 

 rings. These are known as the tympaniform membranes. 

 See fig .7, c, and fig. 6, v. All the sounds which Singing 

 Perchers are capable of uttering are, with a few exceptions, 

 produced with these three vibratmg membranes, namely one 

 semiluna and two tympaniforms. 



These membranes are operated by six pairs of muscles best 

 seen in fig. 8. Descending the trachea we come first, to a 



Fig. 7. Fig. 8. 



Inferior latyiix ut ty;iii-:il 



Singing Pcrcher. 



long muscle which lies on the side of the organ and which di- 

 vides into two parts, one going to the front, and one to the 

 back of the larynx, and adheres to either end of the transverse 

 bone. This is known as the broncho trachealis and its di- 

 vision as the front and back broncho trachealii. Its func- 

 tion is to oscillate the transverse bone, thus producing various 

 tones, as the air impelled by the lungs through either branchial 

 tube, passes along its sides, or is drawn downward fr an the tra- 



