REPORT ON THE BONES OF THE HUMAN SKELETON. 
25 
the tables. In the series of female pelves the mean sacral breadth was 106 mm., and 
the broadest sacrum measured, that of a woman from Oahu, was 122 mm. In the series 
of males, notwithstanding the greater general dimensions of the pelvis and the unusually 
broad sacrum in the Sikh (121 mm.), the Creole (120 mm.), and a Guanche (121 mm.), 
the mean sacral breadth was not more than 107 mm. The mean sacral index in 
the males was 106, in the females 110, so that the sacrum was broader in proportion to 
its length in the women than in the men. The diameter between the postero- 
superior spines was, in relation to that between the antero- superior spines, greater 
in the females than in the males. Thus whilst in twenty males the mean diameter 
between the antero-superior spines was 218 mm. and that between the postero-superior 
spines only 64 mm., in ten females with a mean antero-superior diameter of only 
211 mm., the mean postero-superior was as high as 78 mm. The subpubic angle was 
much wider in the females than in the males ; the range in the males was from 47° 
in an Australian to 76° in both a Chinese and a Malay, the mean of the series being 
64° ; the range in the females was from 71° in a Negress to 102° in an Oahuan and 104° 
in a Laplander, the mean of the series reaching 85°. 
The mean transverse diameter of the brim in the males was 109 mm., in the females 
120 mm. The mean conjugate diameter of the brim in the males was 104 mm., in the 
females 103 mm. Whilst the mean antero-posterior diameter of the pelvic inlet was 
almost equal therefore in the two sexes, the mean transverse diameter was considerably 
greater in the women than in the men, and consequently the brim more usually assumed 
in the women an oval outline with the long axis transverse. These differences are expressed 
in the brim or pelvic index, which had a mean in the whole series of males of 93, in the 
females of 86. The mean intertuberal diameter, which expresses the transverse diameter of 
the pelvic outlet, was 113 mm. in the females and only 90 mm. in the males ; in the females 
the intertuberal diameter approximated to the transverse diameter of the brim in the same 
sex, whilst in the male pelvis the intertuberal diameter fell much below the transverse ; the 
side wall of the pelvic cavity inclined therefore downwards and inwards in the male, whilst 
it was more nearly in the vertical plane in the female. The mean inferior sagittal diameter, 
which expresses the antero-posterior diameter of the immovable part of the pelvic outlet, 
was in the males 104 mm. — precisely the same as the mean conjugate diameter of the 
brim in the same sex, whilst the mean sacro-pubic diameter in the females was 11 3 mm., 
which was considerably in excess of the mean conjugate diameter in that sex ; the antero- 
posterior diameter of the pelvic cavity therefore increases in women very materially from 
brim to outlet. As the pubo-innominate index was in the males 42*7 and in the females 
44, the OS pubis contributed a larger proportion to the breadth of the innominate bone in 
the women than in the men. In the series of adult males the mean ischio-innominate 
index was 43"5, and in the adult females 43"7, so that the proportion which the ischium 
contributed to the height of the pelvis was practically alike in the two sexes. The 
(zooL. CHALL. EXP. — PART XLVii. — 1886.) Aaa 4 
