DEVELOPMENT OF THE SKELETON OF THE TUATARA. 



27 



Fig. 5. Tabular statement of the order of arrangement and succession of intercentra for 



Stages P to T and the adult. 



P. Primary paired iutercentra. U. Unpaired intercentra of primary order. Intercentra absent. 

 F. Secondary intercentra. Chev. Chevrons, f Medially constricted. 



Ribs and Sternum. Ribs were attributed by Giinther to the segments between and 

 including the fourth praesternal (cervical) and the second sacral. Discriminating 

 between the osseous rib as a " pleuropophysis " and its unossified ventral portion as a 

 "haBmapophysis," he further distinguished between those vertebrae in which the latter 

 is fully developed as " dorsal " and those in which it is reduced as " cervical " and 

 " lumbar " respectively. 



For the caudal region he describes the presence of " transverse processes " and 



E 2 



