184 PROCEEDINGS OF THE ANATOMICAL AND ANTHROPOLOGICAL 



room for the growing hemisphere on the same side as the obliterated 

 suture. If the left half of the coronal suture is absent, as in a speci- 

 men No. 3282 in the Anatomical Museum, Cambridge, the bregma 

 will be to the right of the middle line, and the sagittal suture will 

 run obliquely from the lambda forwards and to the right ; it is evi- 

 dent, therefore, that there can have been no atrophy of the brain 

 upon the left side, for if that had been the case the falx would have 

 bulged to the left instead of to the right. 



We may conclude, therefore, from the foregoing cases, that : 



(1) Increased intracranial pressure, though favouring the per- 

 sistence of the cranial sutures, and in some cases of hydrocephalus, 

 being associated with the presence of additional sutures, such as the 

 intraparietal, cannot be regarded as the direct and sole cause of the per- 

 sistence of such sutures as the metopic, for, in certain cases of scapho- 

 cephaly, in which the pressure in the frontal region has been so 

 great that the forehead has actually been bulged forwards so as to 

 overhang the eyes, the metopic suture has apparently closed at the 

 usual age. 



(2) A defective development or atrophy of the brain, though pro- 

 bably favourable to premature or early union of the cranial sutures, 

 docs not as a general rule cause this union, as in the skulls of micro- 

 cephalic idiots the sutures are usually open, and in one case of uni- 

 lateral atrophy of the brain, they were not completely closed, even at 

 the age of sixty-six. 



(3) That the normal closure of the sutures does not coincide with 

 the time at which the brain commences to decrease in size, as the 

 metopic suture closes before the brain has reached its maximum size, 

 and other cranial sutures do not close till long after the brain has 

 attained its maximum, and has commenced to decrease in si/e. 



I shall next discuss the changes in the size of the head, which 

 occur with increase in age. Now it is well known that after the 

 I in me of life has been reached, the average brain-weight gradually 

 diminishes. It has been calculated by Mr. J. Blakeman and Professor 

 Pearson, from data furnished from the />o*t-mortem room at the 



