Abnormaliiies of the Skull. 415 



6. 519. Absence of the Sag-ittal Suture.— Skull-cap, apparently 



of a young person — macerated, illustrating the above. 



The coronal suture is well marked, and is not yet com- 

 pletely ossified. There is, however, no trace of the sagittal 

 suture upon the outside, and only a faint indication of its 

 presence on the inside, a little behind the coronal suture. There 

 are numerous dimples corresponding to the convolutions upon 

 the inner surface. The whole bone is very thin, and is not 

 distinguishable into plates. B. C. i. 3. M. 43. 



6. 520. Absence of the Sagfittal Suture. — Cast in glycerine and 

 gelatine of the interior of the foregoing skull-cap, showing the 

 form of the convolutions which must thus have fitted closely 

 into the depressions on the bone. G. C. 3486. 



II. Changes produced hy Conditions affecting the Growth 

 and Nutrition of the Skull. 



a. Old Age. 



6. 521. Senile Atrophy. — Skull and lower jaw of an old woman- 

 macerated, illustrating the above. 



Tins skull is from the same subject from whom No. 6. 6 and others 

 ■were taken, and which illustrated an unusual form of senile deca3^ 

 The changes in the skull, however, may be taken as illustrating those of 

 ordinary senile decay. 



The sutures on the vault are more or less obliterated. The 

 bones are light, and in many places are atrophied. The outer 

 walls of the orbits, for instance, are in great measure deficient, 

 and the walls of the antrum are as thin as paper. The 

 alveolar borders of the upper and lower jaws are greatly 

 atrophied. The lower jaw is completely cedentulous ; its angle 

 is obtuse, and the narroAved mental foramen on each side opens at 

 or near its upper border. On the upper jaw there are sockets for 

 the roots or stumps of two incisors, and the bone near the 

 sockets is less atrophied than it is elsewhere. The under 

 surface of the skull is somewhat porous. The thickness of the 



