8 
THE VOYAGE OF H.M.S, CHALLENGER. 
pubic symphysis. As the coccyx was so often broken or absent this measurement could 
frequently not be taken. 
19. Intertuberal diameter between the inner borders of the ischial tuberosities 
immediately below the small sciatic notch. 
20. Depth of pubic symphysis is the distance between its upper and lower 
borders. 
21. Depth of pelvic cavity is the distance between the brim near the pectineal 
eminence and the most depending part of the ischial tuber. 
C. Dimensions of the Individual Bones. 
In addition to determining the length and breadth of the sacrum and of the coccyx 
when present, I have taken the length of each of the three elements of the os innominatum. 
The ilium, ischium, and os pubis, both in man and other mammals, may each be regarded 
as having the fundamental form of an elongated rod-like bone possessing three surfaces, 
three borders, and two extremities.^ The central end of each bone terminates in the 
acetabulum, where the three bones become, as is well known, fused together. The 
peripheral end of the ilium is the highest point of the crest, the peripheral end of the os 
pubis is at the pubic symphysis, the peripheral end of the ischium is the most depending 
part of the tuber. The actual line of junction of these bones with each other in the 
acetabulum disappears when the ossification of the os innominatum is completed, but 
there are certain marks at the bottom of the acetabulum in the adult which indicate with 
a fair amount of precision the lines where they have become fused together. The junction 
of the ilium and ischium corresponds almost exactly to the upper border of the non- 
cartilaginous covered surface, where it forms an angle with the posterior border of the 
same surface. The junction of the os pubis with the ischium and ilium corresponds with 
the upper border of this surface opposite the pectineal eminence ; a slight notch in this 
border, or in the margin of the cotyloid, often marks the junction, and 1 have sometimes 
seen a shallow furrow extending across the smooth cartilaginous-covered surface imme- 
diately above the rough area. 
22. Height-length of ilium is measured from the angle formed by the junction of 
the upper and posterior borders of the rough area at the bottom of the acetabulum to 
the highest point of the iliac crest. 
23. Breadth of ilium is the distance between the antero-superior and postero- 
superior iliac spines. 
1 See the description of these bones in man in my article Anatomy in the Encyclopsedia Britannica, ninth edition, 
1874, and in my Introduction to Human Anatomy. In the discussion which followed the reading of Dr. Garson's 
paper on pelvic measurements before the Anatomical Section of the International Medical Congress in 1881, I referred 
to the importance of the rod-like form of these bones and of expressing their iength in tables of pelvic measure- 
ments (see Transactions of Congress, vol. i. p. 190). 
