475 
THE STRUCTURE AND RELATIONSHIPS OF ANCODUS. 
depressed, though not perforated, by the supratrochlear fossa ; the supinator ridge 
is well developed. The trochlea differs from that of Diplopns, Anoplotheriuni and 
Oreodon in the narrowness of the intercondylar or median ridge, which is not the 
rounded, bulging protuberance found in those genera; in other respects it agrees 
best with that of O^^eodon, not possessing the downward, tlange-like prolongation of 
the internal portion, which occurs in Diplopus, and to a much moi’e marked extent 
in Anoplothermm. The internal epicondyle is exceedingly prominent, even larger 
than in Oreodon, and forms a great, swollen rugosity. The humerus of Agriochce- 
rus offers but little resemblance to that of Ancodus, having become differentiated in 
a way extremely like that of certain creodonts, particularly of Mesonyx. 
The radius (PI. XXIV, fig. 6) differs from that of Oreodon in several respects. 
As in that genus, the trochlea for the humerus is divided into three facets, the 
middle one of which is, however, much narrower than in Oreodon, the inner one 
wider, and the outer one difierent in not descending oblicprely forward. Of the 
proximal facets for the ulna the external one is a deep concavity. The head con- 
tracts sharply to the shaft, the upper portion of which is slender and rounded, but 
continually enlarging as it descends, becomes both broad and thick toward the distal 
end. The shaft is strongly bowed forward, but the radio-cubital arcade is short and 
narrow, because the ulna has a very similar curvature. In Oreodo7i the shaft of the 
radius is much more decidedly slender and subcylindrical throughout. In Ancodus 
the distal end is quite massive and heavy^, and has a broad tendinal sulcus on its 
anterior face, enclosed by elevated ridges. The carpal facets for the scaphoid and 
lunar are obscurely separated; that for the former is the larger, convex transversely 
and concave antero-posteriorly, more oblique in position, and is reflected upward as 
a broad band upon the postero-internal angle of the bone. The lunar facet stands 
at a somewhat higher level than the scaphoid; it is broad and concave in front, 
narrower and convex behind. The distal ulnar facet is large and deeply concave. 
The radius referred to this genus by Kowalevsky differs in several respects 
from the one here described. The outer proximal ulnar facet is convex, not a deep 
depression; the carpal facets are broader, less extended in the dorso-palmar direc- 
tion, less oblique in position with reference to the transverse axis of the distal face, 
and more distinctly separated. i j- mi 
The ulna is but little reduced and proximally is heavier than the radius. I he 
olecranon is very large, but low and erect, projecting backward but very little, while 
the antero-posterior diameter is rel.itively very gre.rt. The summit of the process 
is straight, thickened, and somewhat overh.aiigmg to the radial sid^ and the teiidmal 
sulcus is deeply incised, with greatly elevated internal marg n. The s.gmo.d notch 
is low and, except proximally, the articuhar surface for the humerus is confined to 
the inner side; there is also a minute distal extern.,! aeet for the humerus. The 
shaft is of the laterally compressed, trihedral shape found by Kowalevsky m he 
species from Ronton ; it diminishes in site inferiorly. “ 
distal end to fit the corresponding depression on the ladius. le ^ 
the cuneiform is narrow and convex, passing behind into a large flat facet for 
62 JOUEN. A. N. S. PHILA., VOL. IX. 
