220 MR. S. MESSENGER BRADLEY OX THE 



Another point which these tracings serve to illustrate is 

 an absence of bilateral symmetry in human crania. My 

 observations lead me, indeed, to the conclusion that, though 

 the amount of asymmetry differs, no such thing as a per- 

 fectly symmetrical human skull exists. I am not able to 

 say whether extreme cranial asymmetry necessarily involves 

 a greater want of cerebral symmetry. 



I now pass on to say a few words about the facial angle, 

 which, Retzius states, in the Australians, Turks, Circas- 

 sians, Lascars, Tartars, Negroes, &c. is always prognathic. 

 There is no doubt that in the great majority of cases this is 

 true ; but is it sufficiently definite for a scientific classifi- 

 cation ? Is it not fair to ask what departure from a right 

 angle suffices to constitute prognathism ? Does one degree 

 suffice, or are two necessary ? When there is scarcely such 

 a thing as a perfectly vertical jaw, these questions are 

 important. 



Again, amongst the orthognathi Retzius includes the 

 Celtic Scotch, the Irish and Welsh; but any one who 

 has travelled amongst these people would be able to 

 confute the universal (or even general) accuracy of this 

 statement, by bringing forward numerous individuals from 

 these countries who present extreme types of prognathism. 

 Amongst the lower class of the Irish it is the prevailing 

 type; and there is this further interest connected with 

 this subject, that prognathism is a feature which appears 

 to be rapidly acquired by changed external circumstances. 

 Before mentioning the conclusions which I draw from these 

 facts, I may observe that no plan of measuring the dimen- 

 sions of a skull which omits to note the greater or less pro- 

 minence of the occipital tuberosity is likely to be of much 

 value, as this indicates the greater or less degree to which 

 the cerebellum is overlapped by the cerebrum. We should 

 indeed examine the slope of the occiput as carefully and 

 uniformly as we examine the slope and shape of the fore- 



