474 



THE FEATHERED TUIISES. 



be licartl while llic bird is out of sight, its being singularly IdikI and sonorous. The 

 peculiarity, in this instance, consists in convolutions of the trachea before entering the 

 chest. Thus, as the engravings will show, the trachea, instead of going dircctl}' into the 

 chest, enters a large cavity between the two plates forming the keel of the breast bone, 

 and is there doubly reflected before it emerges and ascends to pass into the chest. 



The first represents the breast bone and trachea of the 3'oung Demoiselle Crane. Here 

 the tube r, quitting the neck, passes between the branches of the merrythought {f'urcii/a), 

 A, to the inner edge of the keel of the breast bone, b b, which is grooved to admit the fold. 

 In this groove the fold of the trachea is bound by the cellular membrane : at the point c 

 a small portion of the bone is sawed away to show the depth of the groove which receives 

 the trachea, d is the inferior larynx. 



The following engraving exhibits the trachea in the common crane, running a convo- 





OKGAKS OF THE COMMON CRANE. 



luted course in a cavity in the substance of tlic keel of the breast bone, between the t\vo 

 plates comprising it, one of which is cut partially away to expose the course of the tube. 

 In this, as in the preceding, ihu fiirciihi, A, is not, as in most birds, a distinct bono, but is 

 solidly united to the keel of the breast bone, b. 



