244 THE INTERNATIONAL MONTHLY. 
its widest sense, to include wolves, jackals, foxes, etc., may be 
traced very far back in time. It is altogether probable that this 
family originated in North America ; at all events, this continent 
was the principal area of its development. The dogs began their 
career in the latter half of the Eocene, though their creodont ances- 
try goes much further back. These early dogs were very differ- 
ent from their modern descendants ; almost the only point of close 
similarity is in the character of the teeth. They have large 
skulls, but of very limited brain capacity, short faces, and relatively 
small teeth ; the limbs are short, the forearm and leg bones 
heavy, and the feet are five-toed and plantigrade. The minor 
differences could be made intelligible only by a technically ana- 
tomical description. Suffice it to say, that the fact of especial 
interest and significance is the very close resemblance between 
these primitive dogs and the earliest members of the other car- 
nivorous families, which points to a common origin for them all. 
In the Uinta beds are found two quite distinct lines of dogs, the 
larger and heavier one ancestral to the wolves, etc., while the 
smaller and lighter one may stand in the same relation to the 
foxes. In the White River, the dogs became more numerous and 
diversified, and still more so in the John Day, when there was a 
wonderful increase of the family, representing several distinct 
lines, some of which have died out, while others persist to the 
present time. The principal advances to be noted are the enlarge- 
ment and increased complexity of the brain, the increased size of 
the teeth, the elongation of the limbs and feet, and the loss of the 
plantigrade gait; the animals, like their modern descendants, walk- 
ing on their toes and raising the wrist and heel free from the 
ground. In the Loup Fork substantially the modern condition 
is attained. Of all the Carnivora the dogs are the best and most 
enduring runners, and it is, therefore, not surprising that their limbs 
and feet develop in a very similar way to those of the hoofed ani- 
mals. 
In the Old World members of this family occur from the upper 
Eocene onward, but none that can be regarded as belonging to 
the main line of descent until Pliocene times, when they extended 
