EXPEDITION TO FUNK ISLAND. 



517 



in the depressions for the supraorbital glands are of no value whatever, 

 nor is the varying outline of the region bounded by the supraorbital, 

 temporal, and crotaphyte fossse of much more importance, since these 

 are all characters largely influenced by age. 



Mr. G. K. Gilbert's address on special processes of research sug- 

 gested that the graphic method might be employed to good advantage 

 in showing the relative sizes and range of variation in the crania, and 

 also in some of the other bones, as well as the correspondence in size 

 between bones from th*e right and left sides. 



Diagram allowing the length and breadth of sixteen skulls of the Great Auk. The vertical columns 

 give the length, the horizontal columns the breadth, in millimeters. Black dots indicate parietal 

 breadth; circles indicate frontal breadth. 



The table giving the relative measurements of crania shows that, as 

 might have been expected, the length is subject to greater positive va- 

 riation than either the frontal or parietal breadth, although the com- 

 parative variation of these parts is greater than the linear variation. 

 The table shows very clearly too that the frontal and parietal width of 

 the greater number of crania is the same — 48"^™, and that the frontal 

 width is slightly in excess of the parietal. 



The amount of linear variation is 15°^% the frontal 7™"^, and the pari- 

 etal 8™">. 



