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from the point of division the ccelac artery (A.c@.) is 
given off. From this artery a small vessel arises (A.hep.) 
which turns backwards and enters the liver on the pos- 
terior surface of that organ. The two cceliaco-mesenteric 
trunks then pass internally to the right lobe of the liver. 
One vessel runs in ‘the mesentery, giving origin to 
branches which supply the greater portion of the intestine 
from the anus forwards. The other courses in the mesen- 
teric sheet connecting the liver with the duodenal 
loop, and supplies that portion of the intestine and 
the stomach. 
The dorsal aorta gives origin to a pair of arterial 
trunks in each segment, which supply the muscles of the 
trunk. Towards the posterior extremity of the kidney, a 
large median vessel—the common genital artery (A. gen.) 
—is given off, and passes downwards through the posterior 
portion of the kidney, sending small branches to the 
kidney and suprarenal bodies. This divides into two 
branches, one of which goes to each ovary or testis and the 
adjacent portions of the body wall. The dorsal aorta then 
passes backwards to the tail in the tunnel formed by the 
haemal arches. 
With regard to the venous system, we propose to 
describe the larger venous trunks only. All the blood 
from the head is returned to the heart va the paired 
superior and the unpaired inferior jugular veins. 
The Superior Jugular Veins (V. Jug.) are large thin 
walled vessels which will have been exposed in dissecting 
for the branchial vessels. They receive the blood from 
the eyes and adjacent parts, and accompany the eye 
muscles in the eye muscle canal, emerging from the latter 
through the jugular foramina (f. jug. fig. 2). ‘They then 
run backwards on the ventral surface of the skull over the 
dorsal extremities of the branchial vessels slightly dorsal 
