118 GENERAL BIOLOGY. 



8. A bilobed sac in the angle formed by the 



furcula, the interclavicular air-sac. 



9. Dorsal to each lobe of the interclavicular 



air-sac is one of the paired prebronchial air- 

 sacs. 



Cut through the left pectoralis major muscle dose to 

 the keel of the sternum along its whole lengthy half 

 an inch deep at the anterior end and less deep as 

 the posterior end is approached. From the 

 anterior end continue the cut laterally and 

 dorsally to separate the pectoralis major from 

 the furcula. From the posterior end of the 

 keel continue the cut laterally to separate the 

 muscle from the body of the sternum. With 

 the handle of a scalpel gently separate the 

 pectoralis major from the pectoralis minor be- 

 neath. 

 Note: 



10. The pectoral blood-vessels. 



11. The axillary air-sac. 



12. Note the oesophagus passing posteriorly from 



the crop. 



Cut carefully through the remaining muscle (pec- 

 toralis secundus) close to the keel of the sternum. 

 With strong scissors cut through the body of 

 the sternum close to the keel cut through the 

 furcula and cut away the articulation of the 

 coracoid with the sternum. 



