4-38 STRUCTURE AND CLASSIFICATION OF BIRDS 



In Phitaha ajaja (see fig. 206) the trachea is peculiar 

 in that its bifurcation takes place about the middle of the 

 neck, some distance at any rate before the entry of the 

 bronchi into the thoracic cavity. 



In a female which I measured the bifurcation was three 

 inches in front of sternum, and the distance from the bifurca- 

 tion to the end of the larynx was six and a quarter inches. 

 HUDSON has stated l that there are two species of spoonbill 

 in the Argentine : one has a windpipe like that figured above, 

 and may be considered to be the true ajaja, while the other 

 has a windpipe which is not modified in any way. The 

 characters of the latter apart from the question of the 

 windpipe have been considered by some to be those of 

 immaturity ; but this is denied by HUDSON. 



I have in my possession seven windpipes of P. ajaja, of 

 which two are males and the rest females. In the two males 

 the lengths of the trachea are practically identical. In the 

 females the position of the syrinx varies considerably, being 

 more than an inch lower in some than in others ; this may 

 possibly account for the differences observed b}^ Mr. 

 HUDSON. 



The extrinsic muscles of this species arise from inner side 

 of coracoid, not far from the middle line of sternum. The 

 intrinsic muscles of the syrinx are present ; they cease, how- 

 ever, some little way in front of the syrinx. These muscles 

 are also inconspicuous, and form a very thin though rather 

 wide band. The syrinx is not especially stork-like, except in 

 the fact that the bronchi are for the greater part of their 

 extent tubes with complete rings. The first dozen or so, 

 however, are incomplete, there being thus a membrana 

 tympaniformis. 



There is a cartilaginous three-way piece, and generally 

 there is but little ossification in the windpipe. 



The windpipe of P. alba is different from both the species 

 already described. 



It is not convoluted, but the bifurcation does not take 

 place outside of the thoracic cavity, as in the last species. It 

 1 SCLATER and HUDSON, Argentine Ornithology, vol. ii. p. 115. 



