COMPARATIVE ANATOMY OF THE CIRCULATORY SYSTEM 



23] 



edges, look within and locate the urinary bladder. Note the small vesical veir 

 passing from the bladder into each abdominal vein. Continue to trace the 

 abdominal veins posteriorly. Each passes to one side of the pointed anterioi 

 extremity of the pelvic girdle and at the same time gradually turns laterally 

 As it turns it receives a pelvic vein which runs over the ventral surface of the 

 muscles of the pelvic girdle. The left pelvic vein seems to be usually larger thar 

 the right one. 



In their course between the heart and pelvic girdle each vein gives off laterally 

 one or more small branches which pass to the borders of the carapace where they 

 join the margino-costal vein to be described later. 



Draw the two abdominal veins with their branches thus far noted. 



Continue to trace the abdominal veins in the posterior direction. As both 

 have identical branches it is necessary £0 follow only one, selecting the one which 

 has been most successfully injected. It passes along the dorsal surface of the 

 pelvic girdle near the anterior margin of the latter; the girdle should be pulled 

 toward the student in order to follow the vein. Grasp the hind leg on the side 

 on which you are dissecting and work it back and forth until it is freely movable. 

 Press the leg away from the carapace of that side and cut through the skin between 

 the leg and the carapace back to the end of the tail. Remove the skin from leg 

 and tail. Now trace the abdominal vein laterally along the base of the leg. 

 Just beyond the entrance of the pelvic vein the crural vein enters the abdominal 

 vein from the thigh muscles. About an inch and one-half lateral to this the 

 large femoral vein emerges from the leg and joins the abdominal vein which may 

 now be designated the iliac vein. The femoral vein should be followed into the 

 leg by separating the muscles. The iliac vein is now situated alongside a conspic- 

 uous artery, the epigastric artery, both being imbedded in the abdominal wall from 

 which small veins pass into the iliac vein. After a short distance the iliac vein 

 receives the epigastric vein which accompanies the artery of the same name 

 anteriorly along the curve of the carapace. The iliac vein now turns abruptly 

 posteriorly and runs between the base of the leg and the carapace, deeply 

 imbedded in some loose tissue. This tissue should be cleared away and the 

 vein followed. It receives branches from the carapace and near the posterior 

 part of the thigh a well-marked sciatic vein from the thigh. Posterior to this 

 point it receives several small branches from the leg and as the caudal vein 

 passes along the side of the tail, receiving at the base of the tail a cloacal branch 

 from the anal region. 



Return to the point where the epigastric vein enters the iliac vein. At this 

 place a large vein continues forward from the anterior and dorsal surface of the 

 iliac. This vein, the renal portal vein, runs forward and dorsally, penetrating the 

 pleuroperitoneum. Cut the pleuroperitoneum transversely halfway between 

 the heart, and pelvic girdle, cutting across both abdominal veins. Cut also into 

 the pleuroperitoneum at the place where the renal portal vein passes through it. 

 A layer of muscle will be found outside the peritoneum at this place. Both 



