312 THE OSTEOLOGY OF ELOTHERIUM. 
and thick in the middle portion, but with the distal part quite thin and narrow, and 
tapering to a blunt point; the proximal portion is also narrow and rises above the 
articular surface as a compressed, but thick and rugose process. The femoral surface is 
convex transversely, and only very obscurely divided into external and internal facets by a 
broad and low median ridge. This patella bears very little resemblance to the very thick 
knee-cap of Ancodus and still less to that of Sws. In the latter the patella is a short, rather 
narrow, but very thick bone, the posterior surface of which is of a regularly oval outline. 
Hippopotamus also has a patella which bears but little resemblance to that of Hlotherium ; 
it is short, but very broad and extremely thick, and sends off a long, horizontal process 
from the internal border. 
The tibia is a massive bone, considerably shorter than the femur, but relatively 
heavier. The proximal end is very broad and thick; the condyles are of the usual 
saddle-shaped form and have a rather small antero-posterior extension; the inner 
condyle is somewhat more extended in this direction, while the outer one is wider trans- 
versely, and projects over the external side of the shaft. The fibular facet is small and 
is confined to the postero-external angle of the outer condyle. The tibial spine is low 
and bifid. The enemial process is exceedingly heavy and prominent, and runs far down 
upon the shaft, extending for nearly half the length of the bone; its proximal portion 
displays a depression for the long patella, and the sulcus for the tendon of the extensor 
longus digitorum is deeply incised. The shaft of the tibia is heavy throughout, not 
diminishing much in diameter distally; it has a decided lateral and a slight anterior 
curvature. The distal end is quite broad, but not very thick, and has an unusually 
quadrate outline. The astragalar surface is divided by a low intercondylar ridge into 
two facets, of which the external one is much the larger and the inner one more deeply 
impressed. The intercondylar ridge, which pursues a very straight course across the distal 
end, is remarkable for its bifid termination at the anterior margin. A considerable sulcus 
is placed upon the intercondylar ridge, invading the articular surface on each side. 
On the external side of the distal end of the tibia is a broad, rugose depression for the 
fibula, but with only a very small external facet for the latter ; an additional fibular facet 
forms a narrow band upon the distal surface, the tibia extending somewhat over this por- 
tion of the fibula. The malleolar process is short and compressed, and has no great antero- 
posterior extension. 
The tibia of Anthracotherium (Kowalevsky, 73, Taf. X, Fig. 29) is much like that 
of Elotherium, but is relatively shorter and heavier. Sus also has a similar tibia, differing 
only in minor details. The tibia of Hippopotamus is of the same general type, but is 
extremely short and massive. 
The fibula is complete and is not codssified with the tibia at any point, but is, never- 
