70 
DE. W. KOTVALEYSKY OX THE 
Scheme of the Ungulate Manus and Pes. 
Manus. 
Pes. 
i 
Unciform. 
Magnum, j Trapezoid. 
Trapezium. ; Cuboid. 
Cuneif. 
3rd. 
Cuneif. 
2nd. 
Cuneif. 
1st. 
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The two outer digits of the manus and pes are supported by one bone — the unciform 
in the manus, the cuboid in the pes ; the three following digits in the manus were sup- 
ported, the third by the os magnum, the second by the trapezoid, the first by the 
trapezium ; and in the pes each of the inner digits was supported by its corresponding 
cuneiform. The reduction of the manus and pes commenced at the first or inner toe ; 
and we have not a single living or extinct Ungulate presenting this first digit developed ; 
nay, more, I know of no positive case where even a rudiment of the first toe is present. 
All the bones described as such rudiments have turned out, on close inspection, to be 
the trapezium or the first cuneiform* mistaken for the rudiment of the first digit. This 
is constantly the case in regard to the rudiments described in the ‘ Ossemens Fossiles.’ 
Fortunately, even in the recent period, there still exists an Ungulate upon which we 
may well study the structure of the typical Paridigitate manus and pes. This is the 
Hippopotamus : no trace of the first digit is left in the fore or hind limb; but, owing to 
the very complete development of the remaining four digits, they must have retained 
their typical relations to the bones of the carpus and tarsus. Looking at the fore foot 
of the Hippopotamus (Plate XXXVII. fig. 1) we perceive that the two middle digits 
are mutually interlocked in the manner described above as common to all Paridigitata. 
The two outer digits, the fourth and fifth, are supported by the unciform ; the third is 
supported by the os magnum, and gives besides, at its ulnar margin, a projecting beak, 
by means of which it hangs on to the unciform ; the second digit goes a little higher than 
its neighbours, is supported by the trapezoid, and touches a small facet on the radial 
side of the os magnum ; the first digit is entirely reduced, and its proper carpal bone, 
the trapezium, assists to support the second digit. 
"What do we see in the hind foot \ The cuboid (Plate XXXVII. fig. 9, cb ), 
which is the homologue of the unciform, supports the fourth and fifth digits ; the inter- 
locking of the two middle metatarsals is effected in the usual way, the fourth giving a 
projection which enters into a concavity of the third ; the third cuneiform ( c 3 ) (the 
homologue of the os magnum) supports the third metatarsal ; the second metatarsal is 
* If this absence of even a rudiment of the first digit is really constant among fossil and living Ungulata, it 
may possibly be supposed that at the branching off of the Ungulate division this first digit was already reduced 
and even entirely lost. 
