NOTES ON THE CANID@ OF THE WHITE RIVER OLIGOCENE. 345 
IV. Tue Fore Lines. 
Of the scapula no part has yet been recovered. 
The humerus (Pl. XX, Fig. 15) differs in several important respects from that of 
the recent Canide. Unfortunately, in all of the specimens the proximal end of the bone 
is broken away, so that nothing can be determined with regard to the head, tuberosities, 
or bicipital groove. The shaft is rather short and stout, and is arched strongly forward, 
though less so than in Canis; the deltoid ridge descends low upon the shaft and is very 
prominent, much more so than in the existing canines or felines, though it does not attain 
the exaggerated development seen in the early Machairodonts, such as Dinictis and 
Hoplophoneus. The distal end of the humerus is remarkably cat-like in appearance, and 
does not suggest any relationship with the modern Canide. The supinator ridge is very 
prominent and extends far up upon the shaft, while in Canis this ridge is almost obso- 
lete. The internal epicondyle is very much larger, more rugose and more prominent 
than in the modern genus, quite as much so, indeed, as in the cats, and there is a large 
entepicondylar foramen, bridged over by a stout, straight bar of bone. The anconeal 
fossa is lower, broader, shallower, and altogether more cat-like than in Canis, and does 
not perforate the shaft to form a supratrochlear foramen. The humeral trochlea is 
extremely low, its vertical diameter being conspicuously less than in Canis and less even 
than in Felis, resembling in this respect the humerus of the sabre-tooth Hoplophoneus. 
The shape of the trochlea is of feline appearance, haying a simply convex surface for the 
capitellum of the radius, and no such distinctly marked intercondylar ridge or convexity 
as is found in the recent Canidw. The internal border of the trochlea is prolonged 
downward into a large flange. 
The radius (Pl. XX, Fig. 16) is also singularly eat-like in structure and in all its 
parts is much more feline than canine. The proximal end bears an oval and somewhat 
concave capitellum, for articulation with the humerus; its transverse diameter only 
slightly exceeds the antero-posterior dimension. The anterior notch of the humeral 
surface is somewhat more deeply incised than in Felis, but not more so than in Hop- 
lophoneus, which has an entirely similar capitellum. The articular facet for the ulna 
surrounds more than half the circumference of the head of the radius, which is in 
remarkable contrast to the small size of this facet in Canis. The shape and mode of 
articulation of the bones which enter into the formation of the elbow-joint show that 
Daphenus possessed unimpaired powers of pronation and supination of the manus. In 
the existing members of the Canidae, on the contrary, this power is lost, the head of the 
radius being so much expanded transversely, as to occupy nearly the whole width of the 
humeral trochlea, and interlocking with it in such a way as to allow only the movements 
of flexion and extension. 
A. P. S.—VOL. XIX. 2 R. 
