THE SKELETON 85 
finally, on the assumption of the upright gait, it has changed 
back into an ambulatory appendage. 
This ultimate modification has been accompanied by the greater 
development of the tarsus, and 
by the concomitant degeneration 
and decreasing mobility of the 
phalanges; and, correlatively, the 
foot has acquired a disposition at 
a wider angle to the fore-leg, and 
has become arched in adaptation 
to its supporting function. 
These repeated changes of 
function may well have resulted 
in great structural changes, 
which we may now consider in 
some detail. } 
First, comparing the skeleton | 
of the human foot with that of | 
the Anthropoid Apes, we find the : 
former distinguished by the fol- 
lowing three points (cf. Figs. 60 cb. 
and 62) :— 
(1) Stronger development of 
the great toe." 
(2) Greater development of 
the tarsal elements. ae 
(3) Displacement of the great yo 
Ee pUsimon Gr parallelasmy 2%) 60° SKELETON OF (NHE mex PES 
; OF A CHIMPANZEE, DorRsAL ASPECT. 
with the other toes. 
ec., ecto-cuneiform ; en., ento-cuneiform ; 
If the foot of a second  ms., meso-cuneiform ; cb., cuboid ; nv., 
month’s human fcetus be ex- i a ee aa 
amined, with special regard to 
the last point, it will be seen (Fig. 63, B) that the position of 
the great toe almost entirely agrees with that of the thumb 
(63, A). When the hmbs are laid against the trunk, both point 
towards the head in the position of abduction. 
Whereas this.is the normal lifelong position of the great toe 
of the Apes, and of the human thumb (cf. Figs. 60 and 61) in 
the human foot it is merely transitional, and is abandoned 
OSS eee Ss 
<2 Ss= 
1 We have herein a noteworthy contrast to most of those lower Mammals in 
which the great toe is reduced, or has altogether disappeared. A claw may in the 
former case be found at its distal end (e.g. in the Dog), but even that may disappear. 
