SOCIETY OF THE UNIVERSITY OF ABERDEEN. 191 



tends into the frontal region, the metopic suture has closed earlier than 

 usual, and at the same time as the sagittal, for the median keel or 

 carina, in this position, is characteristic of premature synost-isis of the 

 metopic suture. The most extreme case of this deformity which I am 

 acquainted with is a specimen which was shown me by Professor 

 Macalister in the Anatomical Museum, Cambridge. The breadth of 

 this skull is only 108'3 mm., and its breadth index 56'1. Elongation 

 of the skull is, however, met with in some cases in which the suture 

 remains open ; though it is, so far as I know, not so extreme, and is 

 sometimes a racial character. Again, skulls are occasionally met with 

 in which the sagittal suture has become obliterated, and yet there is 

 no scaphocephaly. In some of these the synostosis may not have 

 occurred until after the growth of the skull had ceased, or the con- 

 dition may have occurred in a normally brachycephalic skull. 



Premature union of the squamous suture sometimes occurs, but 

 very rarely ; an excellent specimen of this is in the Anatomical 

 Museum, Cambridge ; there is reduction in the height of the skull, 

 and compensatory elongation in the occipital region (Plate XII., 

 Fig. 4). 



Early synostosis of the spheno-parietal suture may give rise to a 

 transverse constriction or narrowing of the skull behind the coronal 

 suture; this condition is called " klinocephaly," on account of its 

 saddle-shaped form. The constriction, however, arises independently 

 of the synostosis, and is sometimes due to artificial deformation by 

 bandages. 



Another deformity produced by early synostosis of the coronal 

 suture is " acrocephaly " ; in this, growth being arrested in the longi- 

 tudinal direction takes place in the vertical, the height of the head 

 being increased, and in one specimen which I examined at Cam 

 bridge, the cribriform plate of the ethmoid was depressed, and there 

 was enlargement of the middle and posterior cranial fossae. 



Enlargement of the skull in a downward direction is sometimes 

 plainly visible from the outside in the occipital region, as in one case 

 at the Cambridge Museum, in which the floors of the cerebellar 



