460 CHARLES F. SILVESTER 



Text-fig. 2, A, shows the conditions met with in South Ameri- 

 can monkeys. Here there are two distinct drainage centers, an 

 anterior and a posterior. The anterior, or jugular-subclavian 

 district of communication, drains the thoracic and anterior regions 

 of the body; while the posterior, or reno-postcaval district of 

 communication, drains in general all of that region situated 

 caudal to the thorax. The thoracic and right lymphatic ducts 

 are much reduced in South American monkeys. They drain 

 the heart and lungs and anterior portion of the thorax. The 

 diaphragm and posterior portion of the thorax are drained back 

 into the postcava through recurrent branches of the lumbar 

 trunks. 



Text-fig. 2, C, is a diagrammatic representation of the lymphatic 

 system of mammals in general; showing the modifications made 

 necessary by the conditions met with in South American Primates. 

 The intestinal and lumbar lymphatic trunks may open by reno- 

 postcaval communications or they may open at the jugular- 

 subclavian district through the thoracic duct. The thoracic duct 

 may be situated on either the right or the left side of the aorta, 

 or it may be double, one situated on each side of the aorta, and 

 with numerous cross connecting branches between the two. As 

 a rule, the thoracic duct opens on the left side of the body; it 

 may, however, communicate with the right side, or with both 

 sides as shown in the diagram. 



