serious a nature, that it can in this respect be exceeded only by tying the aorta itself. The common iliac artery is so situated, that it can as easily be reached from the groin upwards as from the side of the abdomen inwards, and in both directions the peritonaeum would have to be disturbed to an equal extent. [Footnote: The student, in operating upon the dead subject, is often puzzled to find that the iliac artery does not appear in its usual situation, unaware at the time that he has lifted the vessel in connexion with the peritonaeum. I have once seen a very distinguished surgeon, whilst performing this operation on the living body, at fault owing to the same cause.] DESCRIPTION OF PLATE 47. A. The aorta at its point of bifurcation. B. The anterior superior iliac spine. C. The symphysis pubis. D. Poupart's ligament, immediately above which are seen the circumflex ilii and epigastric arteries, with the vas deferens and spermatic vessels. E E*. The right and left iliac muscles covered by the peritonaeum; the external cutaneous nerve is seen through the membrane. F. The vena cava. G G*. The common iliac arteries giving off the internal iliac branches on the sacro-iliac symphyses; g g, the right and left ureters. H H*. The right and left common iliac veins. I I*. The right and left external iliac arteries, each is crossed by the circumflex ilii vein. K K *. The right and left external iliac veins. L. The urinary bladder covered by the peritonaeum. M. The rectum intestinum. N. The profundus branch of the femoral artery. O. The femoral vein; 0, the saphena vein. P. The anterior crural nerve. Q. The sartorius muscle, cut. S. The pectinaeus muscle. T. The adductor longus muscle. U. The gracilis muscle. V. The tendinous sheath given off from the long adductor muscle, crossing the vessels, and becoming adherent to the vastus internus muscle. W. The femoral artery. The letter is on the part where the vessel becomes first covered by the sartorius muscle. [Illustration: Abdomen and leg, showing bone, blood vessels and other internal organs.] Plate 47. COMMENTARY ON PLATES 48 & 49. THE RELATIVE ANATOMY OF THE MALE PELVIC ORGANS.