184 
MASARU NAGAO 
The skull was fixed with its basio-nasal line parallel to the hori- 
zontal plane by the use of a bar, and another bar was fixed in such 
a way that it was parallel to the Hne of articulation. The angle 
which was thus formed by the intersection of these Unes at C was 
determined by means of a protractor. The data thus obtained are 
given in tables 2 to 18. 
Fig. 7. The Anterior Half Represents the Skdxl Intact; the Posterior Half 
Represents the Skull Open for the Purpose of Showing the Occipital 
Foramen, and its Two Median Points; Anterior (B) and Posterior (0) 
0, opisthlon; B, basion. The angle ACN is the articular basio-nasal angle 
Vm. COMPARATIVE STUDY OF THE CURVE OF SPEE 
The author's own data 
Before beginning a discussion of the curve of Spee in various animals, 
it should be stated that the total number of skulls employed for this 
study was not large. Therefore, the absolute values of the data 
might be shghtly different were the number increased, although it 
is my belief that any changes subsequently produced would not affect 
the general conclusions stated in this paper. 
For convenience of description and of comparison, the material 
is classified according to the zoological order of the specimens. For 
reasons given in a previous section (III), the curves of Spee were 
compared with each other by comparing the size of the angle at the 
