176 



ELEMENTS OF MAMMALIAN ANATOMY 



(Fig. Syr). It is interesting to compare the embryonic history 

 of the aortic arches with the arrangement found in different 



Fig. 88. — Modifications of the Aortic Arches in Different Vertebrates. 

 {From Kingsley's Comparative Anatomy of Veretebrates, after Boas.) 

 A. Primitive scheme; B. Dipnoian; C. Urodele; D. Frog; E. Snake; F. 

 Lizard; G. Bird; H. Mammal: c, celiac artery; da, dorsal aorta; db. Ductus 

 Botallii; ec, ic, external and internal carotids; p, pulmonary artery; s, subclavian; 

 va, ventral aorta. Vessels carrying venous blood back; those with mixed blood 

 shaded; those which disappear, dotted outlines. 



vertebrates. The schematic diagrams in figure 88 A-H shows 

 the arrangement in fishes (A, B), amphibians (C, D), reptiles 

 (E, F), birds (G) and mammals (H). 



