HUMBOLDT ON THE ORGANS OF THE VOICE. 



than the glottis itself, and this enlargement is nearly fourteen lines long. 

 Lower down, the trachea contracts again and more than before ; for, in 

 entering the inferior larynx, it has not one fourth of its original diameter. 

 I sketched on the spot this peculiar conformation of the Palamedea bi- 

 spinosa, of which I have scarcely met with any analogy in other birds 

 which I have dissected. M. Cuvier, however, has seen two other ex- 

 amples of these sudden enlargements, in the Anas clangula, and in 

 Anas fusca ; but in these cases the swelling was of a spherical form, 

 with a nearly circular disc, and different, in that respect, from that of 

 the Palamedea bispinosa. In this two bundles of very long and slender 

 muscles are attached to the enlarged part of the trachea ; these draw it 

 downwards, so that the larger rings compress those of the narrower 

 part ; a mechanism resembling that of some musical instruments, and 

 which, without doubt, contributes to the production of the monotonous 

 cries and cadences of this bird. 



I shall not dwell long on the structure of the inferior larynx of birds. 

 It would be difficult to add anything to a subject which M. Cuvier has 

 treated of in a particular memoir. I have drawn, in the greatest pos- 

 sible detail, the inferior larynxes of the Psittacus ararauna and of a 

 new species of pelican of New Guinea, which I shall describe under the 

 name of Pelecanus olivaceus. It has the habit of a Plotus ; but its bill 

 and its intermediate claw being serrated, indicate that it belongs to the 

 genus Pelecanus. In one figure the various muscles are delineated, with 

 which nature has furnished this inferior larynx, which is really an 

 instrument of music. The other figure represents the sacs or valves in 

 this bird, which are of an extraordinary size, being more than three 

 lines deep and two broad ; but in some tropical animals which have a 

 very strong voice, this seems to depend on the structure of the superior 

 larynx, rather than on that of the inferior. This is the case with 

 Phasianus garrulus, in which I have represented the bonelets and 



Upper larynx of Phasianus garrulus, opened. 



