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independently, round an axis passing between the sacro-iliac joints and 

 the symphysis pubis. This latter movement is caused by the alternate 

 distribution of the body weight from side to side in walking. It is 

 probable that these movements are largely in abeyance except during 

 pregnancy, when, particularly during the last part of this period, there 

 is said to be some softening of the ligaments, which permits of freer 

 movement than might otherwise be possible. The evidence derived 

 from macerated bones of women of different ages certainly supports 

 this conclusion, for a well-marked sulcus praeauricularis is rare in 

 young female bones, while it is comparatively common in those of 

 mature age. Further, the most striking examples of the groove are 

 invariably associated with ilia exhibiting the female characteristics in 

 the highest degree, as against those which approximate more to the 

 male in their general shape. In other words, a female hip bone with 

 a wide shallow ilio-sciatic notch, and in consequence of this a greater 

 backward projection of the ilium and with it of the sacrum, forms a 

 less secure sacro-iliac joint than one in which these characters are not 

 so pronounced, and therefore throws a greater strain on those liga- 

 ments which resist over-action in these directions. The pelvis of the 

 woman described above, in which the sacro-iliac joints were dissected, 

 is a remarkable instance of this. The ilio-sciatic notch is unusually 

 shallow and the ilia themselves project backwards in such a way that 

 in the ordinary erect posture, the anterior part of the sacrum lies 

 absolutely horizontally between them. The whole weight of the trunk 

 was therefore borne upon the anterior part of a bone lying at right 

 angles to the direction of this weight, and in consequence the tendency 

 towards upward tilting of the posterior end must have been great. 

 This was counteracted by the strong longitudinal band of fibres already 

 described, with the production of the deeply-grooved sulcus which this 

 case exhibits. 



Prof. Hans Virchow^ in the paper already mentioned describes 

 the comparatively poor development of that portion of the groove 

 which lies above the true pelvis. It is this part which corresponds 

 to the "iliac" segment of the ventral ligament. In the cases described 

 by Zaaijer, as well as in the very large number of hip bones which 

 the writer has examined during the past four years, this portion is 

 invariably much less pronounced than that part which lies below the 

 ileo-pectineal line and is confined to the true pelvis. The reason of 

 this is not far to seek after what has been said above, for it is the 

 pelvic part of the joint which moves most freely and upon which the 

 pull of the strong longitudinal band of fibres is exercised. Prof. Virchow 



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