D E F 



FIG. 301. DIAGRAM OF THE ARTERIAL ARCHES OF VARIOUS VERTEBRATES, 



FROM THE VENTRAL SIDE. (After Boas. ) 



A, embryonic condition ; B, Fish ; C, Urodele ; Z), Reptile (Lizard) ; E, Bird ; 

 F, Mammal. The parts which disappear are dotted. 



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

 Birds, and Mammals ; ao, dorsal aorta ; ca, carotid ; k and h, the two first 

 embryonic arches, which almost always disappear ; I, pulmonary artery ; 

 8 (in F), left subclavian artery ; st, and s (in B), ventral aorta ; 1' and 3', 

 first and third afferent branchial arteries ; 1" and 3", the corresponding 

 efferent branchial arteries ; 14, the four branchial arches ; 2 in D and 

 F, second arch of the left side ; 2' in Z>, E ind F, second arch of the right 

 side. 



