SKELETON OF THE WILD DUCK. VERTEBRAL COLUMN. 307 



1. THE AXIAL SKELETON. 



This, as in other vertebrates, is divisible into 



A. The vertebral column. 



B. The skull. 



C. The ribs and sternum. 



A. THE VERTEBRAL COLUMN. 



The vertebral column of the duck, like that of the great 

 majority of birds, presents a number of well-marked character- 

 istics, contrasting strongly with those of the generality of 

 higher vertebrates. The centra are always without epiphyses. 

 The neck is exceedingly long, about as long as all the rest of 

 the vertebral column put together, and is remarkable for its 

 flexibility. The trunk portion of the vertebral column on the 

 other hand is characterised by extreme rigidity, and the 

 marked tendency shown by the component vertebrae to fuse 

 together into one almost continuous mass. The most rigid 

 part of the vertebral column is that to which the pelvis is 

 united, as no less than seventeen vertebrae take part in the 

 union. The tail of the duck, like that of all living birds, is 

 very short, arid the posterior caudal vertebrae are united 

 togther, forming the pygostyle. The vertebral column may 

 be divided into cervical, thoracic, lumbar, sacral, and caudal 

 regions, but the boundaries between the several regions are ill- 

 defined. 



THE CERVICAL VERTEBRAE. 



All the vertebrae anterior to the first one that bears a rib 

 meeting the sternum are regarded as cervical vertebrae. 

 There are therefore sixteen cervical vertebrae, the last two of 

 which bear well developed ribs. All are freely movable on 

 one another. 



As a typical cervical vertebrae, any one from the fifth to 

 the ninth may be taken. The vertebra is rather elongated, 

 and is very lightly and strongly made, its most characteristic 



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