LIGIA. . 85 



soon bifurcates again, the dorsal branch supplying the 

 epimeral (ep. art.) region, and the ventral branch is the 

 crural artery supplying the leg (cr. art.). The inner 

 branches of the first thoracic artery supplying the 

 ventral surface of the first thoracic segment unite 

 in the mid-ventral line at the base of the maxilli- 

 pedes, forming a median artery (PL III., fig. 2) 

 which runs forwards and gives off paired arteries to the 

 maxillipedes (mxp.), second (mx") and first maxillae (mx f ), 

 and terminates in the lingua-like lower lip. 



The sixth thoracic artery soon after its origin gives 

 off a branch which runs ventrally, and unites with its 

 fellow of the opposite side in the mid-ventral line of the 

 intestine; from the point of junction a median artery 

 runs forwards and backwards, forming a sub-intestinal 

 artery. From the sides of the sub-intestinal artery paired 

 transverse branches arise in a very regular manner, and 

 run on the walls of the intestine in the oblique grooves 

 which have been described above. 



The seventh thoracic artery, after running obliquely 

 backwards for a short distance, gives off an artery which 

 bifurcates and supplies the lateral regions of the intestine. 

 It soon gives off from its posterior side a large artery, the 

 abdominal artery which runs posteriorly; the rest of its 

 course is similar to that of the other thoracic arteries. 



The abdominal artery (PI. HI., fig. 1, ab. art.) 

 of each side runs in an undulating manner, midway 

 between the lateral margins and the median line; 

 from it arise small arteries supplying the intestine, 

 muscles and other tissues. In the third abdominal 

 segment it gives off a ventral branch which supplies 

 the three anterior branchiae and the body-wall. The 

 fourth and fifth pairs of abdominal appendages are 

 supplied by an artery which arises from the abdominal 



