SANGUI FERGUS SYSTEM, 



459 



those which, like the area noa, have the ventricle and 

 the bulbus anteriosus double as well as the auricle, the 



FIG. 134. 



anterior and posterior aortae have necessarily also a dou- 

 ble origin. From the bulbus arteriosus (134. e. e.) of 

 each side arises a large single arterial trunk, which imme- 

 diately divides into the usual anterior and posterior aortse 

 (134. f. g.} The two divisions of the anterior aorta, thus 

 formed, anastomose into a single median trunk (134. f.) 

 which advances forwards to near the mouth, sending off 

 numerous large arteries to the ovary, the liver, the stomach, 

 and other viscera of the abdomen in its course. Arrived at 

 the anterior part of the body, this median trunk, greatly 

 diminished in size, bifurcates to form the anterior palleal 



