REPORT ON THE BONES OF THE HUMAN SKELETON. 
67 
was 40*5 to 100, and the mean of two Maoris was 48 to 100. In the Negros the 
proportion was 45*4 to 100, and in the Negresses 49 to 100. In the adult male 
Andaman Islander the proportion was 40 '6 to 100, and the mean in the females was the 
same. In the male Bush the proportion was 53 to 100. The mean proportion in two 
male Hindoos was 45'6, and in a single female 43"6 to 100. In the Sikh it was 47*9, in the 
Malay 47, and in the Chinese 537 to 100. In the male Guanche the proportion was 44, and 
in the female 40'5 ; in the male Esquimaux 49, and in the female 38 '8 ; in the male Lapp 
54*9, and in the female 48 to 100. In not a single skeleton did the proportion of the 
breadth of the body of the 1st sacral vertebra to the entire breadth equal the mean proportion 
in the Europeans as given by Litzmann, and in the majority of cases fell much below it. 
The changes in the form and proportions of the pelvis during its growth have been 
ascribed to various forces acting upon the bones when in a comparatively flexible and 
plastic condition, e.g., the downward pressure of the weight of the trunk on the sacrum, 
the pressure of the heads of the femora on the cotyloid cavities when the body is 
standing erect, the action of the muscles attached to the bones, and the pressure on 
the pelvic walls of the viscera which are developed in the pelvic cavity. Of these forces 
the first two are without doubt those which operate most efficiently. It would be out of 
place to discuss in this Report their mode of operation as two opposing forces, and the 
more so as the argument has been stated with great clearness and force by Dr. J. 
Matthews Duncan in his Researches in Obstetrics.^ I would merely add as corroborative 
of his statement that the heads of the thigh bones exercise an inward and upward pressure 
on the walls of the pelvis in the region of the acetabula, that in a number of pelves, both 
European and exotic, I have seen a distinct bulging of the pelvic wall towards the cavity 
immediately internal to the acetabula, so that the transverse diameter of the cavity at 
this spot is diminished by several millemetres. 
In the adult pelvis the greatest transverse diameter of the inlet is at a point between 
the anterior border of the base of the sacrum and a vertical transverse plane through the 
middle of the acetabula, but somewhat nearer the sacrum than the acetabula. If my 
tables of measurements of the various pelves be examined, it will be seen that the 
transverse diameter of the brim exceeded the greatest breadth of the base of the sacrum 
in the great majority of the specimens. Sometimes, however, in a male pelvis the sacral 
breadth was more than that of the transverse diameter of the inlet. This was the case 
in one Australian, two Negros, a young Andaman Islander, and one Bushman. In a 
male Hindoo the two dimensions were equal. 
In all my adult pelves in which the conjugate diameter exceeded, or was almost the 
same as the transverse, i.e., in the dolichopellic and mesatipellic series, the pelvic inlet 
approximated more closely to the infantile form than was the case in the platypellic 
series ; and in such black races as the Australians and the Bush, the pelvic inlet was 
^ Edinburgh, 1868. See especially his chapter on the Development of the Pelvis. 
(ZOOL. CHALL. EXP. — PART XLVII. — 1886.) Aaa 8 
