The monograph describes the embryonic development of the arteries of a primitive mammal, the tree-shrew Tupaia belangeri, explains the variability among other mammals on the basis of a common developmental pattern, and establishes reliable criteria for the comparison of data published in the literature.Some abnormalities of the arterial system of adult individuals can be interpreted as retentions of a state that normally occurs only during early embryology. Since, for example, the teratogen thalidomide primarily affects the anlagen of the blood vessels and only secondarily the development of the complete limb, it is impossible to understand the normal development of limbs as as well as limb malformations without considering the morphogenesis of their blood vessels.