VERTEBRAL COLUMN 



tissue, extend inwards towards the centre, gradually constricting 

 the notochord so that it may eventually become entirely 

 obliterated. Finally a differentiation, as well as a resorption, 

 extending inwards from the periphery, occurs in these cartilaginous 

 parts : in the interior of each an articular cavity is formed, so that 

 in the vertebras of the higher Urodeles an anterior convexity and 



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FIG. 33. LONGITUDINAL SECTION THROUGH THE VERTEBRAL COLUMN OF VARIOUS 

 URODELES. A, Ranodon sibericus ; B, Amblystoma tigrinum ; C, Gyrinophtiw 

 porphyriticufi (the three anterior vertebne, /, //, ///) ; D, Safamundrina 

 perspicillata. 



'Oh, notochord ; Jrk, invertebral cartilage : OK, vertebral cartilage and fat-cells ; 

 K, peripheral bony covering of centrum ; R, ribs and transverse processes ; S, 

 vertebral constriction of notochord in Amblystoma tigrinum, without cartilage 

 and fat-cells in this region ; **, intervertebral cartilaginous tracts ; Mh, Mh, 

 narrow cavities ; Gp, Gk, articular socket and head ; Ligt, intervertebral 

 ligaments. 



a posterior concavity may be distinguished, both covered with 

 cartilage ; they are, therefore, opisthoccdous. A glance at Fig. 33, 

 A to D, will make this clear. 



In the development of the vertebral column of Urodeles we 

 can thus distinguish three stages: (1) A connection of the indi- 



