24 Account of Observed Forms of Larynx. 



The Ijell-like tones of C. nudicollis are doubtless partly formed by the assistance 

 of such strong inner vocal bands. The apparatus for the tension of this band is veiy 

 peculiar, and reappears in no other bird. According to Rich. Schomburgk's account 

 C. carwiculalus should also possess a bell-like voice. The external vocal band, found in 

 both species on the muscular labium, and the labia themselves, which are specially 

 able to change their form above and below the elastic strap, appear to be still more 

 essential for the production of the voice of these animals. 



(11.) Organ of Voice of tlie Piprinae. 



In Fipra pareola, which is more closely allied to the genus Phoenkercus Sw. than the 

 other P'qmnae, the lower larynx is very different anteriorly and posteriorly. The car- 

 tilaginous rings of the trachea abut, posteriorly, on a rhomboidal shield, which blends with 

 them ; the trachea then, anteriorly, divides, but remains for three or four rings undivided 

 posteriorly, because these rings abut by their inner ends on the already mentioned shield. 

 Theu follow, in tlie bronchus, three broad half-rings, which are completed by the memhrana 

 tynipanifornus ; the succeeding half-rings are thinner. The single vocal muscle, which 

 is extraordinarily thick, arises from the lower larynx, covers the whole of the anterior 

 and lateral portions of the larynx, but leaves the posterior free ; it ends, still broad in 

 form, in the third half-ring. All the fibres have a similar course from above downwards. 

 It is possible to separate three longitudinal portions in the thick muscle. The lateral 

 muscles of the trachea pass down its sides as far as the vocal muscle. The stenio- 

 tracheales spring from the anterior wall of the trachea, and are considerable muscles. 



In the short-tailed Piprinae, P. leucocilla and P. aaricapilla Licht. the lateral muscles 

 of the trachea, by turning forwards, cover the lower part of the anterior wall of the 

 trachea. 



In Plpra leucocilla, the large lateral muscles of the trachea are continued directly into 

 the vocal muscle of the corresponding sides, and further on pass over the beginning of the 

 bronchi to be attached to the third bronchial ring. At the bronchus, each lateral 

 muscle divides into two bundles, an anterior and posterior, which however are left slightly 

 uncovered by the upper surface of the third half-ring. This ring is very large, and 

 osseous, and indeed almost a complete ring. The first and second rings of the bronchus 

 are perfect rings. The vocal band is fastened to the inner surface of the third or large 

 ring. The next half-ring is easily moved, and very thin, as are those which follow. 



The miiisculi sfemofniclieales, which are not connected with the lateral muscles of 

 the trachea in this species of Plpra, are inserted into the sides of the trachea. 



