No. 2.] THE HARD PARTS OF THE MAMMALIA. 175 
that of the Diplarthra, but of inferior fixity. In the baboons 
(Cynocephalus) the relations of the lunar and unciform are as 
in man, while the scaphoides through the centrale, which has a 
strong lateral facet for the magnum, rests entirely on the trape- 
zoides, thus approximating the arrangement in the Amblypoda. 
In Anthropomorpha the metacarpals are nearly in line with the 
carpals of the second row, inclining, however, to articulate in 
addition with the carpal to the zzmer side of them, contrary to 
the arrangement in other Mammalia. This disposition is little 
marked, however, being restricted mainly to the fourth meta- 
carpal, which has more or less contact with the os magnum. 
The relation of the form of the bones of the manus to their 
uses is obvious in this order. The Simiidz use the fore limb as 
a suspensor, as they swing from branch to branch of the forests 
in which they live. The swing of the body on the arm is 
divided into two parts, in which the strains are opposites of each 
other, as to the metacarpal, but identical as to the cubito-carpal 
articulations. The change of relation to the point of suspen- 
sion when swinging from one place to another, is permitted by 
the rotation of the manus and radius round their long axis, so 
that an act of supination is performed. The strain on the 
proximal carpal bones by the radius is then outwards, which 
accounts for the external extension of the scaphoides over the 
magnum. The lunar also is carried by the same strain far 
external to its usual position, entirely covering the cuneiform. 
The latter and the unciform are small, and the cuneiform is 
comparatively unimportant. This restriction of the two ele- 
ments of the external row of the carpus is to be accounted for 
on the ground of disuse. The weight is principally supported 
by the scaphoides and lunar, and the strain passes exclusively 
through them as they only are grasped by the fore arm, z.e. by 
the radius. The ulna has either very slight or no contact with 
the cuneiform, serving merely as the point of suspension round 
which the radius and hand rotate. The relation of the fore-arm 
to progression is quite the reverse of that seen in the Ungu- 
lata, where it sustains so much impact and strain. The meta- 
carpo-carpal articulation is not modified. In approaching the 
position below the point of suspension, the strain of the weight 
is outwards from the fixed point. This presses the heads of the 
metacarpals inwards on the carpus, and the segments proximal 
