1907.] 



AZYGOS VEINS IN MAMMALS. 



189 



affluent from the intercostal space between ribs 5 and 6. As far 

 as the twelfth rib the vein lay outside the intercostal arteries, 

 which up to this point passed between the azygos vein and the 

 vertebral centra. The intercostal artery arising from the aorta 

 between the twelfth and thirteenth ribs passed to the outside of the 

 azygos. Asa rule among mammals this point, where the azygos 

 changes its position relatively to the intercostal arteries, is further 



Azygos veins of Fliacocliwrus cethiopicus. Lettering as in text-fig. 62. 



forward. Anteriorly the precaval vein receives two quite sym- 

 metrically disposed veins, one from each side of the body, which 

 convey blood from the more anterior intercostal spaces. These 

 veins, moreover, are not only symmetrical with each other in so far 

 as regards their point of junction with the precava : they draw 

 blood from exactly the same intercostal spaces. Each consists of 



