MAMMALIA, 517 
all the limb bones of the two types. The humerus of the 
ox has a very prominent great tuberosity which bends over 
the condyle as a hook-shaped process and the bicipital 
groove is single; in the horse there is a double bicipital 
groove and the great tuberosity is simple. The ulna of 
the ox extends down the side of the radius for the whole 
distance, whereas that of the horse has fused on to the 
Fig. 356.—-TIBIOFIBULA OF A Fig. 357.—Ricut FEMuR oF 
Horse x %. (Ad nat.) A Horse. (dd nat.) 
A, Anterior View. Anterior View x 4. 
B, View of Distal Extremity. 
Great 
Trochanter. 
Cnemial Crest. 
Lesser 
Trochanter. 
Third 
‘Trochanter. 
radius more completely, and can be traced only at most 
about half-way down. In the carpus the suture separating 
the os magnum and the unciform is in the middle line, 
whereas in the horse the magnum is much larger than the 
unciform and the dividing suture is towards the outer side. 
This is directly connected with the important difference in 
the manus. Both have been evolved from a pentadactyle 
type, but the ox has lost the first digit or pollex, followed 
