THE FEMALE REPRODUCTIVE ORGANS 301 
isehia with flattened tuberosities and a short symphysis 
parallel to the sacrum ; the outlet is ovoid ; true conjugate 
angle is 65° ; the sacroiliac junction has little motility. 
In the gorillas the following points differ from the last 
described structure. Five vertebrae comprise the sacrum 
and the anterior surface is distinctly concave ; the pelvic 
contour while still ovoid, has the two diameters more 
nearly equal: the pelvic angle is obtuse; the true conju- 
gate is at an angle of 70°. 
In man the salient features of the pelvis are — a 
broad, wedge-shaped sacrum, concave anteriorly, with 
wide articular surfaces and a limited motility; widely 
flaring ilia including the concave curvature of the body 
of the bone whereby the lateral diameter of the pelvic 
inlet becomes wider than in lower orders; short stout 
pubes with a narrowed angle beneath them ; heavy blunt 
isehia "vvith large tuberosities; true conjugate is at an 
angle of 55°. The human fetal pelvis resembles that 
of quadrupeds. 
Study of these data indicates that the quadruped 
pelvis retains many things in common through all the 
orders especially in being a roughly rectangular struct- 
ure lying chiefly horizontally, with a poorly developed 
false pelvis, straight isehia and a long symphysis pubis ; 
the angle of the true conjugate is greater than in man and 
may be up to 80°. The long pubic synostosis changes 
the relation of the true and diagonal conjugate, but the 
former is no indicator of pelvic capacity, since in lower 
mammals the promontory of the sacrum lies anterior to 
the symphysis ; the vertical diameter is a better measure 
of pelvic size and form. Sacral movement seems 
greater in lower animals especially in youth. The shape 
of the pelvic inlet is triangular in the lowest forms, the 
posterior base of this becoming wide as one ascends in a 
zoological line ; the concavity of the ilia also increases so 
that the higher the animal the more curved are the lai>- 
eral borders. In quadrupeds the anteroposterior 
