286 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Second. Tlie wearing away of the teeth wliicli are yet in place is vei-y pronounced. * # » 

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

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

 half, and iinally the aw^fe 0/ ^/tejau' becomes very obtuse. * * » 



Third. The bones of the cranial vault of old persons sometimes are 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 

 tliese senile atr()i)liies is the zone of the parietal comprised between the sagittal sature and the 

 superior temporal line of that bone. 



