344 NOTES ON THE CANID.E OF THE WHITE RIVER OLIGOCENE. 



The shaft of the radius in Daphcenm is slender and has a similar shape to that 

 which we find in the cats, although it is not so much expanded distally ; it is thus very 

 different from the broad, antero-posteriorly compressed and almost uniform radial shaft 

 of the modern dogs. The distal portion of the radius is likewise very feline in appear- 

 ance, but is rather lighter and narrower in proportion to the length of the bone ; it is 

 convex anteriorly and quite deeply concave posteriorly, with well-marked sulci for the 

 extensor tendons upon the dorsal face. The distal facet for the ulna is small and of sub- 

 circular shape and forms quite a projection upon the ulnar side ; upon the inner side of 

 the distal end is a tubercle, which is even more rugose and prominent than in Fells, and 

 more distinctly set off from the carpal surface. This carpal facet has a shape like that 

 seen in the cats, and is more concave transversely and narrower in the dorso-palmar 

 diameter than in the existing forms of Canidce, and its internal border is more prolonged 

 distally into a downward projecting flange. 



Had this radius been found isolated, one would hardly have hesitated to refer it to 

 one of the Machairodont genera, so completely does it differ from the radius of the modern 

 dogs. Fortunately, there is no room for scepticism regarding the reference of this bone 

 to Daphcenm, for several of the specimens, representing different species, have radii of 

 the same type. In this connection, it may be of interest to note that the Eocene creodont 

 genus, Miaeis, which has a remarkably canine type of dentition, has a very cat-like form 

 of radius. 



The ulna is hardly less characteristically feline than the radius. In marked con- 

 trast to the creodonts, which have a very long olecranon, that of Daphcenus is rather 

 short ; its antero-posterior diameter is proportionately less than in Fells, or even than in 

 ('inn's, and its postero-superior angle is thickened and rugose, though somewhat less so 

 than in either of the modern genera mentioned, which gives its proximal border a 

 straighter contour than in them. The tendinal sulcus is wider and deeper than in the 

 recent dogs, less so than in the cats. The sigmoid notch is deeply incised, but describes 

 a parabolic curve rather than a semicircle ; the proximal humeral facet is relatively much 

 wider than in Canis, and is continuous with the broad distal internal facet, which is like- 

 wise broader than in the existing dogs and is shaped much as in the cats, while the 

 external distal facet is nearly or quite obsolete. The radial facet is large, quite dee]fly 

 concave, and continuous or single, while in Cnnis it is much smaller and is divided by a 

 sulcus into two portions. 



The shaft of the ulna is stout and, in the proximal portion, laterally compressed, 

 tapering toward the distal end, when' it becomes trihedral in section. In shape this 

 shaft is very much like that' of the cats and differs entirely from the ulnar shaft of the 

 recent Canidce, which has become very much more slender, reduced and styliform, a 



