Ne@: 2.1] THE HARD PARTS OF THE MAMMALIA. 173 
connection with the carpus and tarsus is maintained. In the 
developed taxeopodous posterior foot, on the contrary, the hallux 
remains for a much longer time, as in Carnivora; and where it 
has been especially used in prehension, as in Quadrumana, it 
becomes enlarged. In man it receives especial strain in recover, 
particularly in those men who turn out the feet in walking. To 
this cause we may ascribe the gradual increase in size of this 
digit, until in the highest races it exceeds the second digit in 
length. 
The above reasoning when applied to the Unguiculate series 
is modified by the existence of other conditions. In the Carni- 
vora the weight of the body does not rest on the ungues as in 
the Ungulata, but on the pads of connective tissue beneath 
the digits. Consequently, on the application of the foot to the 
ground, the distal bones in the carpal and tarsal articulations do 
not present the rigid resistance seen in the Ungulata, but yield 
more or less to the torsion. Hence, no alternation of these bones 
takes place in the hind foot of the Carnivora, where the ever- 
sion of the digits is moderate. In the case of the fore foot, the 
eversion and consequent torsion are so much greater, that the 
alternation is produced (Figs. 17, 18). In the plantigrade bear 
the alternation is almost nil. | 
It may be here objected that the camel walks upon elastic 
pads as do the Carnivora, and yet the alternation has really taken 
place. It is on this account (as I have maintained) that the dis- 
tal metapodial tongue keels were never completed in these 
animals. But if the camel does not rest on the ungues with 
sufficient fixity to resist torsion, thus resembling in some degree 
the Carnivora, the ancestors of the camels, the Poébrotheriide, 
resembled other Diplarthra in this respect. As already pointed 
out, their foot structures were like that of other Artiodactyla, the 
palmar and solar pads of their descendants are of comparatively 
modern origin. Their diplarthrous structure is inherited. 
The carpus of the Anthropomorpha and Quadrumana present 
some interesting modifications. In most of the genera the 
arrangement is taxeopodous, but in the Simiidz the scaphoides 
extends somewhat outwards over the magnum, and the lunar com- 
pletely overlaps the cuneiform (Fig. 19). In man (Fig. 2) the 
lunar extends externally over the cuneiform, and the scaphoides 
rests partly on the magnum, giving an arrangement similar to 
