THE LIFE OF MAMMALS 
group have sprung from a common source. Notable among Miocene fossil 
genera is Amphicyon, whose remains are found in North America as well 
as in Europe, varying from the size of a kit fox to that of a grizzly, and it 
may be termed a “‘bear-dog.” At the same period there abounded on both 
continents the genus Galecynus, containing many generalized species, all 
of moderate size and a foxlike aspect. This type prevailed throughout 
the Miocene epoch, and then gradually gave place to descendants which 
in their central line seem to have developed into true dogs (Canis), al- 
though Galecynus also gave rise to a series of larger and different animals 
(as, in North America Temnocyon, Enhydrocyon, and Hyznocyon of the 
Miocene rocks), most of which presently became extinct. The genus Canis 
seems to have been developed from Galecynus, which disappeared at the 
close of the Miocene, since which Canis has persisted and spread to all 
parts of the world. In its early history the family branched into many 
forms, experimentally, as it were, most of which died out within the Ter- 
tiary period. Among these side lines is one represented by the early Mio- 
cene genus, Oligobunis, —a powerful predatory beast from which, it is 
believed, has descended the South American bush dog (Icticyon); another 
branch gave rise to the #lurodon of the later Miocene formations of our 
plains, whose teeth and jaws show it to have been a big, muscular animal 
with the bone-crushing, scavenging habits of a hyena. The dominant type, 
however, proved to be that leading to the dogs, Canis; and the process 
of development has been in perfecting their running and biting powers. 
They have become better hunters by lengthening the legs, reducing and 
strengthening the toes, which in the early bear-dogs were partly or 
wholly plantigrade, and by the lengthening of the jaws and coincident 
reduction in number and increase in size and sharpness of the teeth; along 
with this has gone an enlargement of the skull and a development of the 
brain beyond that of any other kind of carnivore. 
Our friends the dogs should lead the list by right of their 
advancement, but it will be better first to examine some of their 
wild prototypes, especially the wolves, the most typical and 
powerful of the canine race. 
The great gray wolf, still more or less prevalent throughout 
almost the whole northern hemisphere, measures in 
its largest subarctic form about three and a half 
feet long, exclusive of the somewhat bushy tail, which hangs 
to the hocks, and weighs one hundred and fifty pounds or there- 
188 
Wolf. 
