238 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



injured in the dissection of the renal portal system, try the other side.) It runs 

 laterally to the point where the renal portal vein enters the pleuroperitoneal 

 cavity. At this point it divides. The anterior branch continues to the carapace 

 and runs forward along the curve of the carapace, supplying the fat bodies and 

 becoming continuous with the margino-costal artery described above. The 

 posterior branch turns and passes medially parallel to the ventral abdominal 

 vein. It supplies the base of the leg and the pelvic muscles and terminates on 

 the ventral surface of the pelvis. 



Next follow the common iliac artery of the same side. It divides at once 

 before it has emerged from above the kidney into an internal iliac and an external 

 iliac artery. The external iliac forks after a short distance. The medial and larger 

 branch supplies the muscles of the pelvis and as the femoral artery enters the 

 thigh. The smaller and lateral branch passes deep dorsally to the point where 

 the ilium is articulated to the sacral ribs; here it passes dorsal to a nerve and 

 turns ventrally as the sciatic artery into the hind leg, running along the medial 

 surface of the ilium. The internal iliac is best followed by replacing the kidney 

 against the dorsal wall, pulling the large intestine backward and locating the 

 point of origin of the internal iliacs from the common iliac. The chief branch 

 of the internal iliac is the hemorrhoidal artery which passes forward along the 

 side of the large intestine; in addition there are branches to the bladder, the 

 reproductive organs, and the pelvic region in general. 



Draw the dorsal aorta and its branches. 



8. The structure of the heart. Separate the heart of the turtle by cutting 

 across the great vessels and remove it from the body. The posterior chamber 

 of the heart is the sinus venosus which receives the four great systemic veins. 

 Clean out the blood from the sinus. It is a thin-walled chamber attached to the 

 right auricle, into which it opens by the sin-auricular opening guarded by a pair 

 of thin valves. Open each auricle by making a slit in the margin and washing 

 out the blood clots. The walls of the auricles are somewhat spongy. Look into 

 the left auricle and note the thin inter auricular septum which completely separates 

 the cavity of the left auricle from that of the right one. Find the opening of the 

 pulmonary veins into the dorsal wall of the left auricle near the septum. Find 

 on each side the large auricula-ventricular opening between each auricle and the 

 ventricle. Make a cut all of the way around the margin of the ventricle so as 

 to make dorsal and ventral flaps of the ventricle. Spread apart the two flaps 

 cautiously extending your cut inward until the two flaps are attached only along 

 the base of the ventricle. Note the exceedingly thick walls of the ventricle and 

 the muscular columns projecting into the interior. The cavity of the ventricle 

 is a broad but flattened cavity usually containing a spongy network which may 

 be cleaned out. Spreading the two flaps widely, note in the base of the ventricle 

 a band passing across from one side to the other. On each side of this band is 

 an auriculo- ventricular opening. The band is a continuation of the interauricular 



