184 
PALEONTOLOGY: J. C. MERRIAM 
Proc. N. A. S. 
times known as the true bears, including the brown and grizzly types 
now widely distributed over the whole northern hemisphere. The second 
group is represented by the spectacle bear and is limited to the Andean 
region of South America. 
In the geological period known as the Pleistocene, immediately pre- 
ceding the present, true bears like the present black bear type were asso- 
ciated in North America with a group of large bears known as Arctotheres, 
closely related to the present spectacle bear of South America. In the 
same period South America was inhabited by numerous Arctotheres but 
contained no representatives of the true bears. 
In the rocks of the Pliocene, or second geological period preceding the 
present, until recently no representatives of the bear group have been 
known in either North or South America. In the Pliocene deposits of 
Europe and Asia there are, however, remains of creatures closely related 
to the true bears and with these a second group originally known as the 
hyena bears, or the Hyaenarctos type, closely related in many characters 
to the Arctotheres, and through them related to the modern South Ameri- 
can spectacle bears. 
Assuming that the American bears are descendants of the Old 
World types, it is difficult to escape the conclusion that wide land 
connections existed between North America and Asia, and between North 
and South America, at such times as to permit the migration suggested by 
the present distribution. As the Arctotheres are represented in the 
Pleistocene of South America without accompanying true bears, it is 
logical to assume that the Arctothere group was the first to migrate to 
America and that it passed through North America reaching the South 
American region before the true bears had spread over North America. 
Investigations within the last few years have shown that in the Pleistocene 
deposits of North America both Arctotheres and true bears are present 
together down to the earliest strata in which remains of bears have been 
discovered. There has, therefore, been reason to assume that remains 
of Arctothere-like bears would be found in the Pliocene of America with- 
out associated remains of the true bear type. The point of the present 
paper is to call attention to the fact that recent carefully conducted 
investigations in the Pliocen^e deposits in several parts of North America 
have brought to light remains of bear-like forms which are intermediate 
between the typical hyena bears of the old world Pliocene and the Arcto- 
theres of the American Pleistocene. Such a form is represented by a 
specimen found in the Pliocene of Oregon. This animal corresponds 
very closely to the most specialized of the hyena bears of India and also 
approaches the Arctotheres in its structure. 
The evidence now available indicates that creatures of the hyena bear 
type came by way of broad land connections from Asia to North America 
