312 ' THE OSTEOLOGY OF ELOTHEKIUM. 



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 Sus. 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 Ehtherium ; 

 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 cnemial 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 fin- the tendon of the extensor 

 longus digitoruin 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, hut 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 pn »cess 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 Ehtherium, but is relatively shorter and heavier. tfttsalso 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 coossified with the tibia at any point, but is, never- 



