FIGURES 204 AND 205 



2U4 Transverse section throusih middle thoiiiiic region of a 13.5 mm. cat 

 embryo; (.series 189, slide X, section 15) X 225. 

 205 Same, section 16. 



1 Sympathetic nerve. 



.3 Eight azygos vein, thoracic i)ortion. 



() Left azygos ve.n. thoracic jjortion. 



7 Aorta. 



S Oesophagus. 



84 Ventro-tiicdial nzygos |)lc\ns. 



