FIGURES 13 AND 14 



13 Transverse section of anterior thoracic region in a 15 mm. cat embryo (series 

 219, slide XIV, section 17), X 225. 



14 Same, section 18. 



6 Precardinal or precava, resp. azygos of left side. 

 6' Left azygos vein, thoracic portion. 



7 Aorta. 



8 Oesophagus. 



9 Trachea. 



15 Interazygos segment of thoracic duct. 



22 Vagus. 



36 Azygos segment of thoracic duct. 



53 Precaval lymphatics. 



