* 
O. C. Marsh— Vertebrate Life in America. 373 
mammals made their way, perhaps urged on by the increasing 
cold of the glacial winters) The evidence to-day is strongly in 
favor of such a southern migration. This, however, leaves the 
Old World Bicctare: fossil and recent, unaccounted for; but I 
believe the solution of this ite is essentially the same, 
namely: a migration from North America. ‘The Miocene rep- 
resentatives of this group, which I have recently obtained in 
regon, are older than any known in Europe, and, strangely 
eno ough, are more like the latter and the ete African types 
than like any of our living species. If, now, we bear in mind 
that an ees of only 180 feet would, ‘as hms been said, 
close Behring’s Straits, and give a road thirty miles wide from 
America to Asia, we can easily see how this migration might 
have taken place. That such a Tertiary vie 3 “did exist, we 
have much independent testimony, and the known facts all 
point to extensive migrations of animals over it. 
The Cétacea are connected with the marine Carnivores through 
old type, which doubtless branched off from the more primi- 
tive stock leading to the Carnivores. Oar American extinct 
Cetaceans, when carefully investigated, sumer to throw much 
light upon the pedigree of these strange mammals, As most 
of the known forms were probably ache theif distribution is 
of little service in determining their orig 
That the Sirenians are allied to the ozelhice is now gen 
erally admitted by anatomists, and the separation of the exist: 
ing species in distant localities suggests that they are the rem- 
nants of an extensive group, once widely distributed. The 
large number of teeth in some forms, the reduced limbs and 
other characters, point back to an ancestry near that of the 
‘earliest ungulates. The gradual loss of teeth in the specialized 
members of this group, and in the Cetaceans, is quite parallel 
with the same change in Edentates, as well as in Pterodactyls 
and Birds 
The Vagal are so distinct from other Bones that they 
must be one of the oldest natural divisions of mammals, and 
they probably originated from some herbivorous ats ial. 
Their large size, and great numbers during Tertiary and Post- 
tertiary time, render toa most pene in tracing migrations 
induced by ‘climate, as well as in showing the chan - ) 
structure which such a contest for pee ate may 
n the review of the extinct Ungulates, I have Pdeasored 
to show that quite a nanhee of genera usually supposed to 
