DISSECTION OF THE DOG 



33 



costalis). If this be traced in a ventral direction, it will be found to reach 

 the middle Hne of the sternum, where it meets its fellow membrane of the 

 opposite side. From the sternum the two pleurae are reflected dorsalwards 



u. azijgos 



caudalis 



n. pJiTenicusyvPi'' 



m. obliquus 

 abdominis extemus 



m. rectus abdominis ^ 



m. transversus thoracis !*? 



m. pectoralis profundus 

 m. pcctoralis super/icialis. 



Fig. 10. — Transverse section of the thorax on a level with the eighth thoracic vertebra. 

 4, 6, 6, 7 — fourth, fifth, sixth, and seventh ribs. 



as the mediastinal pleura (pleura mediastinalis). Close to the sternum the 

 two pleurse are intimately associated and a thin double membrane is produced. 

 Soon, however, the heart intervenes between the two mediastinal pleurae 

 [here specifically known as the pericardiac pleura (pleura pericardiaca)], with 



