There is considerable difference between the male and female pelvis, in shape and size. The pelvis in the male is smaller but deeper; the bones are thicker and the brim is more circular, the depth of the symphasis pubis is greater, the sacrum is more perpendicular, the arch of the pubis is narrower, the tuber ischii are nearer each other, and the coccyx less movable. In the female the iliac fossæ are larger, the interval separating the angle of the pubis from the acetabulum is greater, causing the prominence of the hips and wider separation of the thighs, the superior straight is larger and more elliptical, the curve of the sacrum deeper and more regular, the tuberosities of the ischii are further apart, and the arch of the pubis broader. From the greater width of the female pelvis, and from the upper end of the thigh bones being farther apart than in the male, the thigh bones approach each other in their descent, giving a peculiarity to the movements of the female in walking. The soft parts lining the pelvis and covering it externally modify the diameters of the pelvis, but the effect of these additions in diminishing the internal diameter is not very great. The diameter of the cavity is lessened thereby from one-fourth to one-half an inch. USES OF THE PELVIS. One function of the pelvis is to inclose and protect the bladder, rectum and seminal vesicles of the male, the uterus, Fallopian tubes and ovaries, as well as the bladder and rectum in the female. During labor it affords a passage for the child. TERMINAL OUTLET OF THE PELVIC CANAL. This is not at the coccyx, but rather at the anterior commissure of the perineum. This is so greatly distended at the last moment of labor as to much prolong the posterior wall of the pelvic excavation and the canal to be traversed by the fœtus. (Fig. 8). [Illustration: Fig. 9—Section of sacrum and pubis. Measuring superior strait. ] [Illustration: Fig. 10. Measuring inferior strait. ] CHAPTER II. PARTS CONTAINED IN THE PELVIS. The internal organs of generation are the vagina and uterus with its appendages; but I will first describe the urethra and the perineum. The URETHRA is a membranous dilatable canal about an inch and a half in length, and directed obliquely from before backwards, and from below upwards, running under and behind the symphasis pubis, from which it is separated by loose celular tissue. Its inferior portion is intimately united to the vaginal walls. Its meatus, the outlet for the urine, is situated about an inch from the clitoris, and immediately above the prominent enlargement of the anterior part of the vagina.