VASCULAR SYSTEM 



B 



ca „ 



303 



Pig. 243. — Diagram of the Ap.terial Arches pi' Various Vertebrates. 



(After Boas.) 



.4, embryonic condition; B, Fish; C, Urodele; D, Reptile (Lizard); E, Bird; 

 F, Mammal. The parts which disappear are dotted. 



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

 the four more posterior arches ; 1^ and 3^, first and third aiJerent branchial 

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

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

 side ; w, 6, c, the vessels into which the ventral arterial trunk is divided in 

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

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



