Dr Stone on the Frontal Sinus. 89 



6. It is impossible by any external examination of the cranium to predi- 

 cate whether it possesses a large or a small frontal sinus ; an idea en- 

 tertained by many, who imagine that the size of the sinus is indicated 

 by the greater or lesser prominence of the superciliary ridge. This is 

 an error. A large superciliary ridge often exists over a very small 

 sinus ; and scarcely any superciliary ridge at all is sometimes discer- 

 nible, when a very large sinus exists underneath. In specimen 28 (in 

 the collection of crania already referred to) scarcely any sinus is visible 

 on the right side, yet the superciliary ridge above it is strongly marked. 

 In specimen 49 only a vestige of the sinus exists, yet the superciliary 

 ridge is large. In specimens 2 and 29 the sinuses are small, yet the 

 superciliary ridges strongly marked. Whereas, on the other hand, in 

 specimens 8, 23, 34, the superciliary ridges are nearly wanting, yet 

 the sinuses beneath are large. No correlation whatever, therefore, 

 exists between the size of the superciliary ridges and the extent of the 

 frontal sinus. 



It may be added, that the greater or lesser fulness of the frontal 

 bone in this region does not in the slightest degree assist our predic- 

 tions; for the size of the sinus, depending entirely on the extent to 

 which the mucous membrane has risen between the cranial tables, 

 preventing there the deposition of diploe, admits of no external sign. \ 



7. The depth of the sinus bears no proportion whatever to its extent in 



breadth or height. The sinus (as in specimen 16) is sometimes nearly 

 two inches in height, and three in breadth, yet the depth the same as 

 in crania which have the sinuses very small, as in specimen 33, where 

 the sinus does not extend either an inch in height or an inch in 

 breadth. 



8. Vidus Vidian, Duvemey, Dupuytren, and many anatomists, agree in 



stating, that the frontal sinuses attain their greatest extent in old 

 age ; but neither my observations, nor those of Sir William Hamil- 

 ton • corroborate this statement. On the contrary, it appears that the 

 sinuses are generally very small in old age, as may be seen by the 

 specimens 13, 21, 22, 50, — crania which bear all the indications of old 

 age. 



9. The frontal sinuses appear to possess some national peculiarities. They 



appear to be generally small in the crania of the Irish — but very large 

 ' in the crania of the French, Swiss, and Germans. They are small in 



V Negro and Carib crania ; and in the crania of the Hindoos they ex- 



, tend high, but are not deep. In the cranium of the Red Indian, which 



is preserved in the Edinburgh Museum, they are very small f . 



• Sir William Hamilton, whose critical acumen is well known, pointed out 

 to me this, and many other curious facts connected with cranial anatomy. To 

 his investigations, both on this subject and on the cerebellum, anatomists and 

 physiologists are much indebted. 



f The cranixun of the Red Indian was brought from Newfoundland by one 

 of Professor Jameson's pupils, WiUiam Cormack, Esq. and is the only specimen 

 in Europe. It is very valuable, as the Red Indian tribe is now extinct. 



