THE FORE LIMBS. 91 



ends in a large and prominent inner condyle, which does not, however, 

 extend far back of the trochlear snrface, as seen in Plate XXVIII, fig-ure l,a. 



The onter condyle is nearly on the same level as the inner, and 

 extends to about the same distance laterally, from the axis of the bone, as 

 seen in Plate XXVIII, figures 1 and 3. Above, it descends rapidly to the 

 shaft of the bone, and presents only a short and moderately rugose, or 

 nearly smooth, supinator ridge. 



The trochlear articulation considerably resembles that of the 

 elephant, but is placed a little more obliquely to the axis of tlie bone. 

 The radius articulated, during life, with the whole of the anterior part of 

 this surface, and the ulna, with the whole of the posterior part, the former 

 bone being, at the proximal end, in front of the latter, and scarcely at all 

 on the outer side. The outer part of the trochlear surface is more rounded 

 in both directions than the inner, the surface of which is only moderately 

 curved in a transverse direction. 



The shaft of the humerus is more or less cancellated within, as shown 

 in the woodcuts, figures 106 and 107, but is destitute of any medullary 

 cavity. 



FisuBE 106. — Section of humerus of Dinoceras mirabile, Marsh (Xo. 1215) ; near proiimal end. 

 FlGTORE 107. — Section of humerus of Dinoceras iniruhlle (Xo. 1208); below middle. 

 Both tigures are one-fourth natural size. 



Measurements of the humerus in four individuals of Dinoceras are as 

 follows : 



Measrirenients of Left Hunierus. [Dinoceras mirabile, No. 1245.) 



m. 



Total length of hiimerus, . ._- _. -.-- — ■ -SSS 



Antero-posterior diameter of head, .136 



Transverse diameter of head, .120 



Greatest diametet of proximal end, .-.. _ - -220 



Least antero-posterior diameter^ of shaft, .- — ^'^f 



Least transverse diameter of shaft, ■ -080 



