7H 



PHYLUM CHORDATA : CLASS REPTILIA 



globin and others oxyhaemoglobin. At the roots of the two aortic 

 arches there is a minute communication between them — the foramen 

 Panizzce. 



Into the right auricle venous blood is brought by the two superior 

 vena? cavae and by the inferior vena cava. The blood passes through 



Fig. 423. — Crocodile's skull : dorsal surface. 



p.mx., Premaxilla ; mx., maxilla ; /., lachrymal ; pr.f., prefrontal ; 

 j., jugal ; p.f., postfrontal ; q.j., quadrato-jugal ; q., quadrate ; 

 sq., squamosal ; pa., parietal ; e.pt., epipterygoid ; /., frontal ; 

 pt., pterygoid (on lower surface) ; o.t., os transversum (on lower 

 surface) ; n., nasal. 



a valved aperture into the right ventricle, and is driven thence — (a) by 

 the pulmonary artery to either lung, or (b) by the left aortic arch to 

 the body. From this left aortic arch, before it unites with its fellow 

 on the right to form the dorsal aorta, is given off the great coeliac 

 artery. The anterior viscera thus receive wholly venous blood from 

 the heart. 



