The =venæ renales= (Fig. 72, No. 1) are very numerous and originate in the kidney substance, forming two main and several minor branches, which pass posteriorly, and empty partly into the vena hypogastrica, partly into the vena renalis magna, and also into the vena intervertebralis; other branches empty into the trunk of the iliaca communis. The =vena suprarenalis externa= (Fig. 70, No. 30) is located near the anterior rim of the kidney and is connected with the vena hypogastrica. It also receives on the medial side, short branches which come out of the upper kidney surface and sacral vertebræ. The =vena ischiatica= originates by the union of several venous branches which come from the muscles of the pelvis and upper thigh region. The ischiatic vein enters the pelvic cavity along with the ischiatic nerve and artery, and communicates with the vena hypogastrica at about the level of the anterior lobe of the kidney. It is always smaller than the vena cruralis. The =vena obturatoria= originates mainly from vessels from the obturator muscles. It enters the pelvic cavity through the obturator foramen. Another branch is sometimes found which comes out of the inner surface of the peritoneum which covers the obturator muscles and the walls of the abdominal air-sacs and empties between the vena ischiatica and the vena vertebralis into the vena hypogastrica. VEINS OF THE TRUNCUS VENA ILIACA COMMUNIS The =vena intervertebralis lumbalis=, which comes out of the lumbar region, the spinal canal, the lumbo-sacral nerve plexus, and several small venous branches from the lobes of the kidney. It passes dorsalward through the kidney and empties into the iliac vein. There are also communications with the vena intervertebralis thoracica. The =vena renalis magna= (Fig. 64, No. 47) forms the main descending vein to the middle and posterior lobes of the kidney. It lies ventrally and mesially on the middle lobe and partly on the inner part of the posterior lobe. It sometimes has on each side two main trunks. The vein receives some small vessels out of the anterior kidney lobe, also other small veins from that part of the peritoneum which covers the kidney, from the rectum and finally small veins from the ureter. VISCERAL VEINS OF THE POSTERIOR VENA CAVA The =venæ testiculæ=, or the vena ovariana drain the blood from the testicles of the male and ovary of the female. The size of these veins change with the enlargement of the testes or of the ovary during reproductive activity. The =venæ suprarenales revehentes= are short, thick trunks coming from the adrenal glands. The left empties into the left side of the posterior vena cava and the right into the right dorsal side. These receive veins from the testicles in the male and from the ovary in the female.