FIGURES 232 AND 253 



252 Transverse section though lower t horacic region of a 15.5 mm. cat embryo, 

 (series 143, slide XVIIT, section 7) X 225. 



253 Same, section 11. 



1 Sympathetic nerve. 



3 Right azygos vein, thoracic portion. 



G Left azygos vein, thoracic portion. 



7 Aorta. 



34 Ventro-medial azygos plexus. 



36 Thoracic duct, azygos segment. 



