PLATE 13 



EXPLANATION OF FIGURE 



14 Cross section showing the anastomosis between the cardinal collateral 

 and azygos veins in a 23 mm. Tragulus embryo. Collection No. 228. 21, cardinal 

 collateral vein; 24, aorta; 28, azygos segment of the thoracic duct; 51, azygos 

 vein; 61, anastonosis between cardinal collateral and azygos veins. 



246 



