76 
DE. W. KOWALEYSKY ON THE 
not a single bone of their skeleton was figured or discussed comparatively until the 
appearance of Professor Gaudey’s work on the Fossils of Pikermi*. 
However, I was so fortunate as to see many bones of the skeleton of the Miocene 
Suina, distributed into divers genera, in the collections of Paris and London ; and on 
comparing the third metacarpal of the Palceochcerus f (Plate XXXVII. fig. 6) from 
Auvergne, and the Choeromorus , Lrt., from Sansans, with that of the recent Suidae, I 
found that this broadening of the third metacarpal did not exist in Palceochcerus nor in 
the Choeromorus, the second digit taking for its support the entire surface of the trape- 
zoid. Plate XXXVII. fig. 6 represents a third metacarpal of Palceochcerus ; and 
by comparing it with fig. 4 we immediately perceive the difference. This broadening 
of the metacarpals, with the purpose of taking the whole of the distal surface of the 
second row of bones of the carpus, took place in the Suina only after the middle Miocene 
epoch. But, among the recent Hogs, we have one more advanced form which, in this 
character, stands to the other Suidae nearly in the same relation as the Suidae stand to 
the Palaeochoeridae ; this is Picotyles. The structure of its fore limb agrees entirely with 
that of Sits, only the lateral metacarpals are reduced a step further ; and looking at 
fig. 5, Plate XXXVII., we shall see that the enlarged third metacarpal has taken, not 
the half, as in Sits, but the tvhole of the distal surface of the trapezoid, the second 
metacarpal being pushed entirely away from its typical carpal bone. Moreover, this facet 
for the trapezoid (as in fig. 4) is transformed from an oblique into a horizontal one, 
thus giving better support to the third digit ; while the corresponding distal surface of 
the trapezoid instead of having a spear-shaped form, as in the Hog (fig. 4, t ), is quite 
flat in Picotyles (fig. 5, t). The trapezium (fig. 5, tz) is greatly reduced, has no distinct 
articular facet on the trapezoid, and is disappearing altogether, without coalescence with 
the trapezoid. Thus, then, we find that, in the Miocene Pigs, the whole trapezoid is, 
according to the typical relations, taken by the second digit ; in the recent Hog only 
half of its distal surface is left for the second digit, and none at all in Picotyles. 
On the outer side of the manus, the relations are much simpler, as the fourth and 
fifth metacarpal are supported, in all Ungulata, by a single bone, the unciform ; there- 
fore, by the gradual broadening of the fourth metacarpal, the outer or fifth digit is 
pushed to the outer side of the distal surface of the unciform, until, in the Hog and in 
Picotyles , it occupies only a small lateral and outer facet on this bone, in such a way 
that the fifth digit has practically no upper carpal facet, but is suspended laterally to 
* Gervais, ‘ Paleontol. Eraneaiso,’ has figured a third metacarpal, which is very interesting, as it shows none of 
the broadening of the radial margin so characteristic of Sus. It is from the right side, while all figured by me 
are left. 
t In its dental characters, as well as in its skeleton, Palceochoerus stands so near to the Hog that even 
their generic distinction might be questioned. The Choeromorus, being- also a true Hog, stands further from 
the recent Suidte ; one of the very curious characters of this remarkable genus is the central ridge of the distal 
extremities of the metacarpals and metatarsals, which, instead of encircling the whole extremity, is limited to 
its back part only ; the first phalanges are modified accordingly. 
