LYMPHATICO-VENOUS COMMUNICATIONS 453 



There are three general points of communication which were 

 found to be more or less constant in position, and although these 

 three points were found to be present, to the exclusion of all 

 others, in only one individual (fig. 4, Cebus hypoleucus), this 

 might be designated as the typical arrangement for the reason 

 that at least one of these three openings was present in every 

 individual examined. These three points of communication are 

 connected with three lumbar trunks as follows: 



(1) A lumbar trunk from the left side and opening into the 

 •left renal vein near the sex-vein; (2) a lumbar trunk coming from 

 the right side, crossing the ventral surface of the postcava, and 

 opening at the juncture of the left renal vein and the postcava; 

 and (3) a trunk from the right side opening into the postcava 

 near the right renal or right sex-vein. The first two communi- 

 cations were present in more than 75 per cent of the individuals 

 examined. The third was not nearly so constant; it represents, 

 however, the only trunk opening on the right side. 



The lumbar trunks of the two sides may join and have a com- 

 mon opening, either into the left renal vein (Cebus capucinus, 

 No. 2559), or at the juncture of the left renal vein and the post- 

 cava (Midas oedipus, fig. 10). As a rule, however, the trunks of 

 the two sides have separate openings into the veins. They 

 remain distinct except for numerous cross anastomoses which 

 occur between the two sides (figs. 1 and 7). Anastomoses between 

 the lumbar and mesenteric trunks, as mentioned above, are also 

 of common occurrence (figs. 2 and 7, Ateles variegatus, 2563, 

 Cebus hypoleucus, 2574). 



As mentioned above, the lumbar trunks of the two sides, as a 

 rule, have separate openings into the veins. For this reason 

 the right and left lumbar trunks are considered separately. 



a. The right lumbar lymphatic trunks. The lumbar lym- 

 phatic vessels of the right side may present a single communica- 

 tion on the right side of the postcava, either cranial to the renal 

 vein (Cebus hypoleucus. No. 2480), or caudal to or at the level of 

 the renal vein (figs. 4 and 7, Cebus hypoleucus). The right trunks 

 may also open on the left side of the postcava in similar relations 

 to the left renal veins (figs. 3 and 9, Ateles vellerosus and Calli- 



