ABSORBENT SYSTEM OF MAMMALTA. 



511 



400 



close to its termination : a single trunk terminating altogether on 

 the right side of the conflux of the internal jugular and subclavian 

 veins, in which case a short lymphatic trunk is found on the left 

 side similar to that which usually exists on the right, constituting 

 a partial lateral inversion or transposition confined to the trunks 

 of the lymphatic system. The right lymphatic trunk nearly equals 

 the thoracic duct in dia- 

 meter ; it is, however, not 

 more than half an inch in 

 length. Its situation is in 

 the neck at the level of the 

 lower edge of the seventh 

 cervical vertebra, lying 

 close to the inner edge of 

 the ' scalenus anticus,' 

 and opposite to the union 

 of the subclavian and in- 

 ternal jugular veins, at 

 which point it terminates 

 in the venous system. It 

 receives the lymphatics of 

 the right upper extremity 

 and of the right side of 

 the head and neck, those 

 from the right lung and 

 right side of the heart, 

 some few from the right 

 lobe of the liver, and from 

 the exterior and interior of the right upper half of the body. 

 Sometimes the trunk of the cervical lymphatics, fig. 400, c, enters 

 separately the jugular vein,^. 



§ 345. Mammalian modifications. — The lacteals in Dasyurus 

 viverrinus converge to two subelongate, dark-coloured mesenteric 

 glands ; one of them situated near the pylorus, at the end of the 

 pancreas. The cy sterna chyli is plexiform in the Marsupials 

 which I have examined ; in the Kangaroo it lies upon the crura 

 of the diaphragm, and extends upon the right side above the dia- 

 phragm into the thorax. Two thoracic ducts are continued from 

 the cy sterna, one along the left, the other along the right side of 

 the bodies of the dorsal vertebrae. The right duct crosses the 

 seventh vertebra and joins the left, which again divides and re- 

 unites, forming a slight plexus, before finally terminating at the 

 confluence of the left subclavian and jugular veins. The double 



Tlio thoracic duct and right lymphatic trunk ; Human 



CLXX". 



