Shinkishi Hatai 439 
out to be skew (that is a non-linear regression) then the relation should 
be more complicated and a simple proportion would fail to correctly 
express the relations existing between the two characters under consid- 
eration. On the other hand if the regression is linear the relation may 
sometimes, but not always be shown by a simple proportion just as well 
as by a characteristic equation. 
(1) Fronto-occipita] length, ¢ = 0.5326 Entire skull length, #@ + 4.226 
(2) Fronto-occipital length, 2 = 0.6663 Ob . ibd ? — 1.311 
(8) Squamosal distance, ¢ = 0.1100 oe ce se o% + 10515 
(4) Squamosal distance, 2 = 0.1004 a sf Se 2 + 10.884 
(5) Height of skull, FS = 0.1634 ve es “ o+ 4.425 
(6) Height of skull, 2 = 0.0937 Re yy ts G+ 7.246 
(7) Length of nasal bone, & = 0.4911 WS i Ye 3 — 4.285 
(8) Length of nasal bone, 2 = 0.5619 oe ee 6 2 — 7.654 
(9) Capacity of cranium, od = 0.2790 ee ee se fo — 1.172 
(10) Capacity of cranium, S = 0.2863 Mw ee ee S— 1.627 
(11) Zygomatie width, SF = 0.6243 ee rt fo — 5.259 
(12) Zygomatic width, & = 0.5830 se ss oe 5 — 3.298 
(13) (Height x length x width)3, ¢ = 0.2590 ‘ se ue o + 56.672 
(14) (Height x length * width) 3B so 0:29 cs Nad sf 6+ 7.619 
(15) Brain-weight, g% = (0.0072 Body-weight, ¢% + 9.849) + 5.980 
(16) Brain-weight, 6 = (0.0251 ie 5 + 6.168) + 6.009 
CONCLUSIONS. 
1. All the characters here examined are absolutely greater in the adult 
male than in the adult female. 
2. The coefficients of variation reveal the fact that the male characters 
show a general trend to a greater degree of variability than those of the 
female. The length of the nasal bone and the zygomatic width show a 
much greater variation than any other skull characters in the two sexes. 
3. The coefficients of correlation are always positive and tend to be 
higher in male than in female. The correlation between cranial capacity 
and body-weight was found to be quite high (0.516 in male and 0.692 
in female). 
4. The brain-weight corresponding to the observed body-weight may be 
calculated from the following two characteristic equations: 
Brain-weight, male = (0.0072 & (body-weight, male) + 9.349) + 
5.980. 
Brain-weight, female = (0.0251 & (body-weight, female) + 6.168) ~ 
6.009. 
5. The observed sexual differences are considerably reduced when the 
length of the entire skull is equated to either the male or female standard. 
When the lengths of the entire skull in the two sexes are equated and 
