DOUBLE LEFT PAEIETAL BONE IN A SCOTTISH 

 SKULL. By Professor Sir William Tukner. 



In 1884 I described and figured in the skull of a native of the 

 Admiralty Islands ^ a skull in which the right parietal bone 

 was divided into an upper and lower part by a suture which 

 passed almost horizontally from the coronal to the lambdoidal 

 suture. In 1891 I also figured a similar specimen in an 

 aborighial Australian skull.- In these papers I called attention 

 to the cases of a corresponding kind which had been noticed by 

 previous observers. 



I have now to refer to a third adult skull in the University 



Museum, in which a similar division exists, but in this specimen 



in the left bone. The skull is that of a Scotchman. It was 



found a number of years ago at a burial-place in Dunbar, and 



forms a part of the collection of the old Phrenological Museum. 



The suture is strongly denticulated, and completely divides the 



left bone into two unequal moieties. The upper part was 



106 mm. in antero-posterior diameter and 78 mm. in vertical 



diameter ; the lower part was 104 mm. in antero-posterior and 



38 mm. in its least vertical diameter. At the anterior or 



coronal end of the dividing suture two small sutural bones were 



interposed between it and the coronal suture, and the skull was 



depressed somewhat in this region. The lambdoidal and 



coronal sutures were strongly denticulated, and a small epip- 



teric bone was situated in each pterion. All these sutures were 



distinctly marked on the inner table, though much more feebly 



denticulated than in the outer table, and it was observed that 



small sutural bones were differentiated in this table both at the 



lambdoidal end of the intraparietal suture and within the 



lambdoidal suture, as well as those already referred to in the 



exterior of the skull. A short paracondyloid process projected 



downwards from the under surface of the left jugal process. In 



other respects the ossification of the skull was normal. 



' Challencfcr Reports, part xxix. plate iv. p. .'J7. 



- Journal of Anatomy and Physiology, vol. xxv. pp. 462-473. 



