AIISINOITIIERIUM. 
51 
there is on either side of the bone a prominent tuberosity {i.t., o.t.). Tbe posterior 
surface of the shaft immediately above the condyles is slightly concave from side 
to side, the concavity being bordered by ridges running upwards and inwards from the 
tuberosities. The lower end of the bone is much narrower than the upper end. 
The femur of Uhitatheriuin differs in the following points: — (1) it is not so 
much compressed from before backwards, and at the same time it is considerably 
narrowed from side to side near its middle ; (2) there is a small but prominent 
lesser trochanter ; (3) the hinder surface of the great trochanter is hollowed by a 
digital fossa ; (4) the distal articular end is relatively larger. 
The femur of Elejihas differs from that just described in the following points: — 
(1) the neck is much longer; (2) the great trochanter does not rise nearly so high 
and its posterior face is excavated by a deep digital fossa ; (3) the shaft is not 
compressed to anything like the same degree, and its posterior face is not so much 
flattened ; (4) the distal articulation is relatively larger. 
Text-fig. 29. 
Right patella of Arsinoitherium zltteli : A, from inner side ; B, from articular face. 
i., inner surface for femur ; o., outer surface for femur ; pr., distal process, j nat. size. 
The patella (text-fig. 29) is much like that of Uintatheriimi. The surface for 
the outer condyle [o.) of the femur is smaller than that for the inner (i.); both are 
gently concave from above downwards, and very nearly flat from side to side. Below 
the articular surface the bone is produced downwards into a blunt triangular 
process {pr.). The anterior face as usual consists of a greatly swollen and roughened 
mass of bone. 
The tibia (text-fig. 30) is a short stout bone considerably expanded towards 
the articulations. The facets for the condyles of the femur are deeply concave. The 
inner {i.) is much the larger and is oval in outline, the long axis being antero- 
posterior. The outer (o.) is smaller and more nearly circular, and its long axis 
is from within outwards : in front of it and to the outer side of the anterior 
H 2 
