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THE OSTEOLOGY OF HY/ENODON. 
The bones of the fore-arm display a considerable degree of variation among the 
different species. In H. horridus the ulna is relatively short, but massive and not 
at all reduced. As is so very generally the case among the creodonts, the olecranon 
is very high ; it projects quite strongly backward and terminates in a heavy, rugose, 
and club-shaped swelling, which overhangs somewhat toward tire internal side ; it 
is not grooved bv a tendinal sulcus. The sigmoid notch is high and deep, and the 
coronoid process is very prominent. The notch is somewhat oblique with reference 
to the long a.xis of tlie bone, inclining downward and inward. Except proximally, 
the humeral surface is confined to the inner half of the sigmoid notch, but there is 
a small distal external facet for the humerus, which presents upward. The radial 
facet forms an uninterrupted concavity, the ends of which project beyond the sides 
of the shaft; the projection on the outer side is much the more prominent of the 
two. The shaft is laterally compressed, but very stout, rounded and convex on the 
inner side, deeply channelled on the outer. Its principal diameter is the antero- 
posterior one, which gradually diminishes downward, while 
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