4 i8 



ELEMENTAR Y ANA TOMY. 



[LESS. 



second meets its fellow of the opposite side above to form 

 the dorsal aorta, while the third sends one branch forwards 

 to the skin and another backwards to the lung. Here the 

 aortic arches are not broken up by any interposed minute 

 ramifications. 



Again, as in Cryptobranchus, we may have two arches on 

 each side, all meeting to form the dorsal aorta, and each 

 hinder one giving off a branch to the lung. This condition 



FIG. 362. MAIN ARTERIAL VESSELS OF CRYPTOBKANCHUS. 



(After Hyrtl.) 



a, atlas vertebra ; b, bulbus arteriosus ; c, c, arteries going to the mouth ; d, d, 

 anterior, and e, e, posterior aortic arches meeting at e ', the two conjoined arches 

 further uniting at d'; f,f, pulmonary arteries ; g, external maxillary artery ; 

 h, internal carotid ; i, vertebral ; k, left subclavian ; /, right subclavian ; ;;/, 

 spinal artery. 



reminds us of that early stage in man (before noticed) when 

 the ductus arteriosus connects the pulmonary artery with the 

 aorta ; only in Cryptobranchus, we find such a connexion per- 

 sisting on both sides of the body, while in man the right 

 great aortic arch has aborted. 



We may also have, as in the Crocodile, two aortic arches 

 given off respectively from the right and left ventricles 

 uniting in the dorsal aorta ; or finally, as in man's class and 



