480 



ANATID^. 



The trachea of the male Velvet Scoter is remarkable for 

 a hollow bony enlargement situated about two-thirds down 

 the tube, made up of expanded tracheal rings, which in the 

 adult are firmly ossified together. Upon each side of this 

 enlargement a small muscle passing downwards is inserted 

 upon the inner side of the shaft of the merrythought. On 

 making a longitudinal lateral section, as shown in the out*- 

 side figures below, the inner tube of the trachea, at its upper 

 part, exhibits an aperture on each side by which it communi- 

 cates freely with the cavity within another bony enlargement 

 situated immediately below the superior larynx, and brings 

 to mind the laryngeal cavities found in some of the higher 

 animals. A slip of paper is represented as passing through 

 both apertures. 



