n8 Prim tpal Differenc es Between [Book IX. 



cartilage at the fore part of the pelvis, which is called 

 the fymphyfls pubis. In each os pubis we may ob- 

 ferve the body of the bone, its angle, and ramus. The 

 body or outer part is united to theos ileum; the angle 

 comes forwards to form the fymphyfis, and the ramus 

 is .a thin procefs which unites with the ramus of the 

 ifchium to form the foramen thyroideum. 



The acetabulum, or focket of the thigh-bone, 

 which is partly formed by all the three bones which con- 

 flitute the ofTa innominata, is placed at the under part 

 of the pelvis, and is turned obliquely outwards. The 

 acetsbulum is not a perfect circle in the fkcleton, the 

 under part being fupplied in the recent fubjedr. by 

 cartilage. 



The os pubis conftitutes about one- fifth of the ace- 

 tabulum, the os ileum makes Something lefs than two- 

 fifths, and the os ifchium as much more than two- 

 fifths. 



The pelvis has two openings, one above and one 

 below j that above, when we (land in the erect pofture^ 

 pointing almoft directly forwards, that below, almoft 

 directly backwards. 



The chief differences between the male and female 

 Skeletons are in the proportions of the bones of the 

 pelvis. The cavity of the male pelvis is an irregu- 

 lar circle j that of the female is much larger, and of 

 an oblong (hape ; the longed diameter being from 

 fide to fide, and the fliorteft from the os facrum to 

 the oiTa pubis. Hence women are much wider acrofs 

 the hips, in proportion to their height, than men. 

 The os facrum is broader, and turned more back- 

 wards for enlarging the pelvis. The os coccygis is 

 more moveable, and much lefs bent forwards, to faci- 

 litate delivery. In confequence of the pelvis being 

 wider in women, the articulations of their thigh- 

 bones 



