4 7 ; | JANUARY, 
The base of the inferior left canine was found in its socket; the remainder was 
found broken; the fragments were put together so as to make almost a complete 
tooth, which presents no specific characters of any importance; the anterior 
margin is more rounded than in D. torquatus, and the grooves on the posterior, 
external, and internal faces of the fang are deeper; the young of D. torquatus 
in the depth of the grooves agrees perfectly with our fossil, which, however, 
from the wearing of the tooth, must have been an adult. 
The condyloid process of the right lower jaw was found broken off just below 
the neck; in comparison with D. torquatus, it is less concave in its external out- 
line, and there is a slight depression externally just below the end of the articular 
surface; the posterior face a little below the articular part is more compressed 
and less flattened than in D. torquatus. 
The inferior extremity of the humerus is perforated; the articular faces are in 
no respect different from those of D. torquatus. 
The same is the case with the innominatum and the femur. 
Of the left posterior foot is preserved the calcaneum, the outer metatarsal, th 
first and second phalanges of the outer toe and the first phalanx of the inner toe; 
all these bones completely resemble the corresponding parts of D. torquatus. 
As compared with Platygonus compressus, the caleaneum shows important 
characters,.which may be used in separating the bones of these animals, if they 
should again be found mixed together. 
In Platygonus the astragalian face is not distinctly defined at its supero-external 
part, but is confluent with the depression existing in that part of the bone 
behind the fibular process. 
In Sus and Dicotyles this face is distinctly separated from the valley between 
the two processes, and the inferior part of the astragalian process is much less 
thickened than in Platygonus; the whole bone is more slender and less flattened 
than in Platygonus. 
My reasons for considering the cuboides figured by me* as belonging to Platy- 
gonus, are as follows: 
From teeth there was evidence of two specimens of Platygonus of different 
ages; portions of three caleaneal bones of the left side were found, two of which 
were precisely similar; the third is the one here mentioned as belonging to 
Dicotyles. The larger of the two similar bones fitted perfectly with the ex- 
tremity ofa tibia, an astragalus and a cuboides forming a considerable portion 
of the tarsus; to this cuboides, however, the metatarsal bone above described 
cannot be adapted. 
This will be the proper place for correcting an important error in the memoir 
on Platygonus already quoted: on page 270, pl. 4, figs. 23 and 24, is represented 
what was considered the zxner metatarsal. On comparison this bone is found to 
correspond accurately with the inner right metacarpal of Dicotyles; there are 
two specimens of this bone, differing slightly in size, and the smaller one of 
whieh has lost its lower extremity, and evidently belonged to a young animal. 
We have therefore the same reason to refer this to Platygonus as the tarsal bones 
abeve mentioned. 
I should also notice here, that the superior canines of very young Dicotyles 
resemble very closely those of Platygonus, but are not so much compressed, and 
have only a single angulated line at the anterior part of the base of the tooth. 
On account of the very strong resemblance between the dentition of Platygonus 
and Dicotyles, I am inclined to consider the former as rather Suiline than Tapi- 
roid in its affinities; the undulated outline of the lower jaw in the Dicotyles 
group, reaches its maximum in the great dilatation of the angle of the jaw in 
Platygonus; the compression of the canines is carried to a greater degree than in 
any other genus, and the molar structure is reduced to the simplest Pachydermal 
form by the absenee of all accessary tubercles. 
The dimensions of the fragments of Dicotyles depressifrons indicate an animal 
* Memoirs Am. Acad. of Science and Arts, New Series, Vol. 3, pl. 4, figs. 25, 26. 
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