In glancing over the appended table, it will be seen that the male pelvis exceeds the female in most of its vertical dimensions, while the female pelvis is larger in the horizontal di ameters. The depth of the true pelvis, however, measured at the sacro-coccygeal column, is greater in the female, on account of the greater size of the sacrum in that sex, and also because of the less total vertical curvature. The depth from the pectineal eminence to the lowest point of the ischiadic tuberosities laterally, and at the pubic spn physis anteriorly, show, on the contrary, a great superiority in the male; as also does the total depth of the whole pelvis, from the highest point of the ilium to the most de pending part of the ischium, while the width between the iliac spines and crests are much greater in the female. The horizontal dia meters of the pelvis may be said to depend upon the element, while the depth or vertical measurement depends solely on the element, so that, in the feniale, the former may be considered to prevail, and in the male, the latter element. This is re rnarkable, as constituting the different pelvic properties of certain classes of animals.
It will also be observed that the transverse diameter of the brim is the greatest in the dry bones, but this is so diminished by the presence of the iliac and psoas muscles and fascia, that, in the living female subject, the oblique is generally the best adapted to receive the long diameter of the fletal skull. The soft structures diminish the antero posterior diameters of the brim by about a quarter of an inch , and the transverse, by half an inch ; the diameters of the cavitybeing lessened about a quarter of an inch ; a fact which it is necessary to bear in mind in estimating the width in the living subject. The measure ments in the third double column were taken from fourteen male and eighteen female sub jects in the dissecting room of King's College, London, and are compared in the first column with the contrasted measure ments of the male and female pelvis given by Meckel, and quoted by most English writers on the subject; and in the second column with those given by John James Watt, in his work on the pelvis.
The circumferential measurement of the brim in well-formed nzales gave in my own mea surements 2 inches to each of the ilia, 3 inches to each of the pubes, and 41 to the sacrum, which, allowing inch to each of the sacro iliac cartilages and + inch to the pubic, gives a total circumference of 15+ inches. In the well-made fenzale the ilia were found to be each 21, the pubes each 3+, and the sacrum 5 inches, giving, with the same allowance for the sacro-iliac cartilages and + inch for the pubic, a total of 171 inches. Thus the
superior size of the brim in the female seems to depend more upon the ilia than upon the pubes, although the direct distance between the ilio-pectineal eminence and the sacro-iliac joint differs little in the sexes, because of the greater curve made by the female ilia. The circumferential extent of the borders, at the plane of the inferior outlet in a female pelvis of average diameters, and dried with the sacro sciatic ligaments attached, was 11 inches. In the fresh state it generally amounts to 13, as the lig,aments shrink by drying, and would be extended to 16 inches, or more, by the ex tension of the coccyx and the elasticity of the ligamentous portions.* Burns gives also, in the female pelvis, the following distances : 1. Between the symphysis pubis and inferior iliac spine, nearly - - 4 in.
2. sacro-iliac joint and the pubic crest of same side - - 3. sacral promontory and the obturator notch 4. sacral promontory and the acetabula 5. /I acetabula anteriorly - 4i 6. posterior ridge of ilium and the su perior and inferior anterior spines - 5 7. centre of iliac crest and the brim of the pelvis, direct - One of these measurements was repeated by Velpeau, Stoltz, and Naegele, viz. frorn the sacral promontory to the centre of the cotyloid cavity, or sacro-cotyloid. Naegele in 54 and Stoltz in- 40 female pelves, found the mean distance to be 3 pouces, 3 to 4 lignes (pied du Roi).
Dr. Murphy, considering that the true salient point or promontory lies on a level above the real pelvic brim, at the saero lumbar fibro-cartilage, gives also three more measurements made in the " inclined plane of the promontory," one antero-posterior, be tween the fibre-cartilage and the upper border of the symphysis, which he places at 4 inches, and two lateral, from the same point to the pectineal eminences, which are on an average about 31. inches, but which are seldom equal, because of the great tendency to deviation of this promontory from the median line. The latter seem to coincide almost with those given by Dr. Burns between nearly the same points, and the former with the conjugate diatneter of the brim.
External measurements of the female pelvis, made on the liviug subject, have also been given, though from few data, as follows : 1. External antero-posterior diameter, 7 to 8 inches.
2. External transvers e, between iliac crests, 13 to 16 inches.