THYMUS IN THE MARSUPIALS. 557 



g.s. Sympathetic ganglion. 

 is. Isthmus of thyroid. 

 I. Lung. 

 m.sh. Sternohyoid muscle. 

 m.oh. Omohyoid muscle. 

 m.sm. Sternomastoid muscle. 

 m.p. Pectoj'alis muscle. 

 m.st. Sternothyroid muscle. 

 OS. CEsophagus. 

 pc. Pericardium. 

 st. Sternum. 

 sm. Submaxillary gland. 

 ton. Thymus. 

 tm.a. Anterior lobe of thoracic thymus. 

 tjn.c. Cervical lobe of thymus. 

 tm.p. Posterior lobe of thoracic thymus. 

 th. Median lobe of thyroid. 

 th'. Right lobe of thyroid. 

 th". Left lobe of thyroid. 



tr. Trachea. 

 v.c'. Right superior cava. 

 v.c". Left superior cava. 



vg. Vagus nerve. 

 v.f. Internal jugular vein. 

 v.j". External jugular veiu. 

 /., //., ///. Eibs 1 to 3. 



LINN. JOURN. — ZOOLOGY, VOL. XXVI. 40 



