148 



MORPHOLOGICAL TYPES 



The ductus arteriosus is also called the 



into a ligament 

 ductus Botalli. 



The vena cava superior of each side is made up of the 

 jugular and subclavian veins, and opens into the right auricle. 

 In some forms the left superior vena cava is connected with the 

 right by a transverse innominate vein, and so loses its own 

 opening into the right auricle. The left vena cava superior 

 also receives at its base the thoracic duct which connects with 



bvi 



Fig. 63. — Diagram showing the relations of the arterial arches and the 

 branches of the vagus nerve in : A, Scyllium, and B, Lepus ; seen 

 from the left side. 



al y anterior laryngeal nerve ; bv 1, 3, 4, and 6, blood-vessels (arterial 

 arches) running in the first, third, fourth, and sixth visceral arch ; ca y 

 carotid arch ; d, ductus arteriosus ; da, dorsal aorta ; Et, Eustachian tube ; 

 g 1, first gill-slit ; h, heart ; m, mouth ; pa, pulmonary artery ; rl, recurrent 

 laryngeal nerve ; s, spiracle ; sa, systemic arch ; t, tonsil ; v, vagus nerve ; 

 vb 1,4, first, fourth branch of the vagus nerve. 



the system of lymphatic vessels. The posterior cardinal veins 

 are represented by the azygos (right) and hemiazygos (left) 

 veins of the wall of the thorax. The hemiazygos connects 

 with the azygos, which opens into the right superior vena cava. 

 The connexion between the hemiazygos and the left superior 

 vena cava has been lost. 



The walls of the heart itself are drained by veins, called 

 coronary veins, which open into the right auricle. 



