280 MEMO11JS OF TUB NATIONAL ACADEMY OF SCIENCES. 



Second. The wearing away of the teeth which are yet in place is very pronounced. * * * 

 The alveolar point mounts almost up to the level of the nasal spine; the mandible reduces itself 

 to its basilar portion; the height of the symphysis of the chin is found reduced more than one- 

 half, and finally the angle of the jaw becomes very obtuse. * * * 



Third. The bones of the cranial vault of old persons sometimes arc subject to an interstitial 

 resorption of the spongy tissue; the two compact tables of the bone become fused in one compact 

 and semitransparent plate, and from this result the undulating depressions characteristic of 

 senile atrophy, which are the certain signs of an advanced old age. The most ordinary seat of 

 these senile atrophies is the zone of the parietal comprised between the sagittal sature and the 

 superior temporal line of that bone. 



