in the Egyptian Tantalus. 501 



the ducks, having only a trifling enlargement of that organ and 

 of the bronchi. 



The Cracidce and CapricalccB (Urogatlus) exhibit also ma- 

 nifestations of similar conformation, as well as an individual of 

 the Cassican family, described by M. Lesson in his " Manuel 

 d'Ornithologie," under the title Fhonygama Keraudrenii, and 

 probably in other birds whose larynges and tracheae have not 

 as yet fallen under my notice. 



The very remarkable circumstance of the tracheae in many 

 birds, especially those of the order Naiatores, being ossified and 

 composed of various pieces, and each ring being entire (not as 

 in man and mammalia, having a muscular membrane occupy- 

 ing the posterior third part of the canal), which possibly can only 

 be accounted for from the apparent necessity of the air being 

 required to remain in the body of the animal, rarefied in readi- 

 ness for the purpose of raising itself, whenever it may be induced 

 to wing its flight through the atmosphere ; and assuredly aquatic 

 birds must be rendered very buoyant in consequence when 

 swimming. 



The bodies of the pelican {Onocrotalus), gannet {Sula), and 

 chaja {Palamedea Chavaria) may be inflated almost like a blad- 

 der between the skin and muscles ; so also, but partially, that 

 of the powting pigeon, the adjutant, marabou, and tachypetes, 

 but particularly the emeu, whose trachea, somewhat below the 

 middle of the neck, being there deficient in cartilaginous rings, 

 is formed into a membranous sac, which can be distended at 

 pleasure : and everybody has seen the male turkey, in the pride 

 of dominion, enlarge its breast and even menace the spectator ; 

 faculties clearly tending to accelerate progression when required. 

 : With few exceptions, birds, having a crop, are not furnished 

 with inflexions, or obvious deviations from the apparent ordi- 

 nary 



