38 
DR. W. KOWALEVSKY ON THE 
Dimensions of the Radius. 
Hyopotamus. 
Hempstead. 
Puy. 
Transverse breadth of the proximal extremity 
30 
32 
Antero-posterior depth of the upper surface 
20 
19 
Transverse breadth of the distal extremity. These 1 
extremities seem to be epiphyses of radii of y 
32 
30 
young individuals j 
The Femur. — Of this bone I had a complete specimen from Puy (fig. 5, Plate XXXVI.), 
an upper half of a smaller species from Hempstead (fig. 6), and a lower half 
(Plate XXXV. fig. 2) from the same locality, but belonging evidently to a larger indi- 
vidual or species than the upper half. I had no femur from Hordwell, and consequently 
this bone is unknown in Diplopus. 
Confining our comparison only to the Paridigitate series of Ungulata, of which Hyo- 
potamus is one of the old representatives, we find in our fossil femur characters that are 
very common to all the members of this division. In comparing the ruminant and non- 
ruminant Paridigitata, we find that the femur in the Suina has a more complete 
spherical head supported on a pretty distinct neck, the great trochanter rising very 
slightly or not at all above the level of the femoral head, and a small (or inner) tro- 
chanter not very prominently developed, and often consisting merely of a rugose thick- 
ening at the antero-posterior edge of the superior half of the femur. The general shape 
of the bone is very round in Hicotyles, more flattened in other pigs, and slightly arched 
from behind forwards. Both edges of the anterior part of the distal articular surface 
(rotular surface) are alike, while the internal condyle is thicker than the external ; the 
transverse breadth of the trochlear surface for the patella is proportionately broader in 
comparison with the entire thickness of the distal end than in Ruminantia ( Ficotyles 
forms an exception to this rule, and the rotular breadth of its femur presents the same 
relation to the whole thickness of the distal end as in Ruminantia). Now the femur of 
Hyopotamus shows characters that are common to both divisions of Paridigitata. The 
head of this femur is supported on a neck (fig. 6) even more distinct than in the Suina, 
and approaching that of Hippopotamus. The great straightness of the whole femur 
reminds us also of this last genus. The spherical head is provided with a deep pit for 
the round ligament, which is absent in Hippopotamus. This round articular head is 
connected with the prominent small (inner) trochanter by a very sharp ridge, as in some 
Suina, only the ridge is higher and sharper (fig. 6'). The bridge of bone (fig. 6, a ) con- 
necting the head of the femur with the great trochanter is much contracted in the 
middle, and lowered in such a way that both articular head and great trochanter rise 
considerably above the level of the connecting bridge — a character very general among 
the Paridigitata, with the exception of the Camelidce , in which the superior end of the 
femur is shaped on a plan entirely different from other Ruminants, presenting a great 
resemblance to the Imparidigitata ( Rhinoceros ) in the breadth of the connecting bridge 
