390 NOTES ON THE CANID® OF THE WHITE RIVER OLIGOCENE. 
Canis, and its anterior border is notched by the obturator sulcus. The acetabulum is 
small, deep and nearly circular. 
The anterior or descending ramus of the pubis is long and slender and encloses with 
its fellow a broad anterior pelvic opening. The horizontal ramus is proportionately 
longer and stouter and the symphysis is longer than in the recent dogs, almost as long as 
in the cats. The horizontal ramus is less flattened and depressed than in the former, 
forming a prominent ridge along the ventral side of the symphysis. 
The os penis may be conveniently described in connection with the pelvis. - In none 
of the White River specimens that have fallen under my observation is this bone pre- 
served, but in the beautiful specimen of C. geismarianus figured by Cope (85, PI. 
LXX) it is present and in nearly its natural position, though Cope has omitted any 
mention of it in his description. Flower (69) has pointed out the characteristics of this 
bone in the three sections into which he divides the fissipede carnivores. The Arctoidea 
“all have a large penis with a yery considerable bone, which is usually more or less 
curved, somewhat compressed, not grooved, dilated posteriorly and often bifurcated or 
rather bilobed in front” (p. 14). The cats and viverrines “all have a comparatively 
small penis, with a more or less conical termination, and of which the bone is small, 
irregular in shape, or not unfrequently altogether wanting” (p. 22). To this statement 
Cryptoprocta forms an exception, haying a bone relatively long, “slender, compressed, 
slightly curved, not grooved or divided anteriorly, rounded and slightly dilated at each. 
end, but thickest posteriorly ” (p. 23). In the hyzenas the bone is wanting. The dogs 
resemble the raccoons, weasels, ete., in having a large os penis, “though the os is of a 
different form, being straight, wide, depressed and grooved” (p. 26). In Cynodictis this 
bone is entirely different from that of the modern Canide ; it is long, slender, compressed 
laterally and strongly curved and is slightly grooved upon the sides, but not on the dorsal 
border ; the anterior end is so broken that the presence or absence of a bilobation cannot 
be determined. The resemblance in the character of the os penis between Cynodictis, 
on the one hand, and Cryptoprocta and the mustelines, on the other, is an important fact, 
the significance of which will be discussed later. 
The bones of the hind limb proper considerably exceed in length those of the fore 
limb, more so than in Canis, though the difference is rather between the proportions of 
the radius and tibia than between those of the humerus and femur. : 
The femur is slender and quite elongate and in essentials differs but little from that 
of Canis. The head is small, of hemispherical shape, and is set upon a somewhat longer 
and more distinct neck than in the modern genus, projecting more directly inward and 
less upward ; the pit for the round ligament is deeply impressed but very small. The 
great trochanter is lower than in Canis and is separated from the head by a narrower, 
