XII 



PHYLUM CHORDATA 



461 



the neck, the rigidity of the trunk-region, and the shortness 

 of the tail. There are fourteen cervical vertebrae, the last two 

 of which have double-headed ribs (Fig. 260 cv. r.} each 



,_ '-) SSL'S 



jig 7i* 8 



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O H.H 



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 3 s o 



s'ltl" 3 



5l'^l 



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X . vl .3 3' 



having its proximal end divisible into t\\ehead proper articulat- 

 ing with the centrum of the vertebra, and a tubercle with 

 the transverse process : their distal ends are free, not uniting 



