FIGURE 154 



154 Transverse section through ventral portion of upper thoracic region in 

 a 20 mm. cat embryo (series 241, slide, XIX, section 18), X 225. 



3 Right preoaval vein. 



7 Aorta. 



8 Oesophagus. 



9 Trachea. 



10 Pulmonary artery. 



18 Peritracheal venous plexus. 



22 Vagus. 



37 Broncho-mediastinal duct. 



