OF THE PELVIS. 39 



terior face, and the sacro-pubal or coccy-pubal diameters are to a 

 greater or less degree diminished, while the antero-posterior diame- 

 ter is found to be larger than natural; in other instances, although 

 very greatly curved, it is not the less removed to a great distance 

 from the pubis, whether at its base or apex. 



In the second case, the anterior face of the sacrum being actually 

 plane, or even slightly convex, as may be seen in a specimen belong- 

 ing to the collection of the Ecole, the pelvic cavity, instead of dilating 

 betwixt its straits, becomes smaller, or on the other hand, it enlarges 

 regularly, from the promontory to the pomt of the coccyx; according 

 as the base of the sacrum seems to have see-sawed forwards or 

 backwards. 



97. When the sacrum is too concave, and when both the straits 

 are narrowed, if the head, by means of great efforts, comes down to 

 the excavation, it stops there, becomes locked, can neither advance 

 nor retreat, and renders the labor so dangerous that even the Cae- 

 sarian operation itself might be insufficient for its termination. If 

 it be too straight, and the lower strait is too much contracted, the 

 head will descend at first very promptly, but as it passes through a 

 conical canal, it will soon be arrested, and with difficulty clear the 

 apex. 



98. Whenever narrowness of one of the straits coincides with ex- 

 cessive amplitude of the other, the progress of the labor is neces- 

 sarily perplexed. Is the abdominal strait faulty through insufficient 

 amplitude? the head will long remain arrested at it, but will pass 

 through at last; then, meeting almost no resistance, it will traverse 

 the apex of the pelvis with great celerity, at a moment perhaps when 

 the accoucheur, judging of the duration of the labor by the time 

 that has been already occupied, is informing the assistants that seve- 

 ral hours must elapse before it can be concluded. Has the inferior 

 strait, on the contrary, lost its dimensions? the foetus engages with 

 extreme quickness, and the practitioner, who does not suspect the 

 real condition of the pelvis, announces that the woman will speedily 

 be relieved, whilst perhaps the very best planned succors are becom- 

 ing indispensably necessary. 



99. If the symphysis pubis forms a crest projecting backwards a 

 few lines, as I have seen it do in two instances, it does not prevent 

 the delivery from being accomplished; but during the passage of the 

 head it may contuse the bladder and the uterus, and favor the 

 laceration of these organs. Sometimes one of the acetabula projects 

 into the excavation, or it may be one of the sciatic spines, turned 

 very much inwards, that deforms the cavity, as was observed both 

 by Levret and Madame Lachapelle; exostoses of every sort and 



