MECHANISM OF THE CIBCULATION. 



67 



as the leech and earth-worm) there exists, on the other hand, 

 a complete vascular apparatus ; but generally there is no 

 heart, properly so called, and the blood is set in motion by 



Branchial Artery. 



Arterial Bulb.., 



Ventricle of the 

 Heart. 



Auricle of the 

 Heart. 



Venous Sinus. 



Vena Portae, 

 Liver, &c. 



Intestine. 



Vena Cava. ~W''T~"~~\" 



Branchial Vessels. 



Dorsal Artery. 



Kidneys. 



Dorsal Artery or 

 Aorta. 



Fig. 52. Circulatory Apparatus in the Fish. 

 Jf 2 



