.l.Y.Y.l/.S Y/:n YORK ACADEMY OF Si ICACFS 
150 
Table I. 
Ameghino 
1900 
Roth 
IMS 
Camiry 
1900 
PLEISTOCEN E 
) 
1 
Pam peon 
Pliocene 
■ Pam pea n 
IV. 
Pam pean 
Miocene 
. 
1 
. 
Santa Cruz 
Oligocene 
1 
111. 
Santa Cruz 
and 
Patagonian 
Patagonian 
Eocene 
} Santa Cruz 
and 
| Patagonian 
IT. 
■ Pyrotherium 
i 
' 
Pyrotherium 
Notostylops 
Upper Cretaceous 
j Pyrotherium 
1 Notostylops 
I. 
Notostylops 
A wide diversity of opinion exists as to the correlation of these formations 
of the Argentine Republic, older as well as more recent. Comparison with 
European standards is peculiarly difficult on account of the isolation of the 
faunae and the lack of corresponding and closely related, not to say identical, 
genera and species in them. In the absence of such direct data, recourse 
must be had to more indirect means of correlation, — 
First , to the relative stage of evolution shown in the faume compared. 
Second, to their near or remote relationship to the modern faume of 
the same region, as exhibited in the proportion of extinct to living species, 
genera and families. 
