VASCULAR SYSTEM 

 B 



303 



ca. 



D E F 



FIG. 243. DIAGRAM OF THE ARTERIAL ARCHES OF VARIOUS VERTEBRATES. 



(After Boas.) 



A, embryonic condition ; B, Fish ; <7, Urodele ; Z>, Reptile (Lizard) ; E, Bird ; 

 F, Mammal. The parts which disappear are dotted. 



k and h, the two first embryonic arches, which almost always disappear ; 1 4, 

 the four more posterior arches ; I 1 and 3 1 , first and third afferent branchial 

 arteries ; 1" and 3", the corresponding efferent branchial arteries ; 2 in D and 

 F, second arch of the left side ; 2 1 in D, E and F, second arch of the right 

 side ; a, b, c, the vessels into which the ventral arterial trunk is divided in 

 Reptiles, Birds, and Mammals ; ao, dorsal aorta ; ca, carotid ; I, pulmonary 

 artery ; 8 (in F}, left subclavian artery ; st, and s (in B), ventral aorta. 



