NECTURUS 11 



giving off a twig to the urinary bladder in its course. Trace the 

 femoral artery along the posterior side of the thigh to its division 

 at the knee and trace both branches into the foot. 



The femoral vein also occurs on the posterior side of the leg 

 Trace it proximally to its junction with a renal portal vel* 

 which extends along the outer side of the mesonephros, reaching 

 forward to the genital region. Behind, the renal portal \eins of 

 the two sides unite and receive a caudal vein from the tail as well 

 as smaller pelvic veins. From each femoral vein there also arises 

 a pelvic vein, the two uniting to form a ventral abdominal vein 

 which runs forward in the ventral body wall and eventually passes 

 into the liver through the mesohepar, to unite with the hepatic 

 vein. Trace the renal portal vein of either side forward to the 

 anterior limits of the coslom. The portion of the vessel in front 

 of the mesonephros is called posterior cardinal vein. 



Add these parts to your sketch. 



Now trace the connection of the femoral artery with the 

 aorta and trace the aorta, now called the caudal artery, into the 

 tail, noting the cloacal branches. Do you find spinal or inter- 

 costal arteries (p. 8) in this region? 



Add these to the sketch together with the pulmonary artery 

 and vein, the latter on the ventral, the former on the dorsal, side 

 of the lung. Trace both as far forward as the septum. 



The Heart. Cut through the ventral wall of the body just 

 in front of the fore legs, laying open the pericardial cavity in 

 which the heart lies. Note that the cavity is lined with a smooth 

 membrane, the pericardium, comparable to the peritoneum. In 

 the heart make out the following parts: Behind and attached 

 to the septum transversum, the sinus venosus. Anterior to 

 this on the ventral side, the thick, muscular ventricle, from 

 which a tube, the truncus arteriosus, leads to the anterior wall 

 of the pericardial cavity. Dorsal to the ventricle are a pair of 

 auricles. 



Inflate by blowing into the part of the postcava left attached 

 to the liver. Does this demonstrate a connection of postcava 

 and sinus venosus? 



Lay open the ventricle from the ventral surface and, if neces- 

 sary, remove the blood or injecting mass from the interior. Fol- 

 low forward with the incision, splitting the ventral wall of the 

 trunctis arteriosus. Do you find any valves between ventricle 



