2i6 The American Geologist. 
October, 1905 
the skeleton is necessary to determine whether they may 
not after all be remotely related to the Lemurs (order 
Cheiromyoidea) as Cope and Wortman have suggested. 
Wortman is strongly of the opinion that the Eocene Prim- 
ates (Notharctidae, Anaptomorphidse) are not Lemuroidea, 
and that the former family are distinctly South American; 
this also requires confirmation. 
Search for the exact relations and points of connection 
between the Carnivora and Creodonta, has thus far been 
entirely without definite success ; in other words, the true 
Carnivora seem to be as separate from the Creodonta as the 
true Perissodactyla are from the Condylarthra. 
As regards the Artiodactyla, as yet very little is known 
of the "Middle and Lower Eocene stages, among which it is 
especially important to test the truth of Scott's 4 broad gen- 
eralization that the American Artiodactyla should all be re- 
garded as affiliated to the Tylopoda as a stem group from 
which not only the Camelidas evolved but also, the other 
distinctively American Artiodactyls, such as the Oreodon- 
tidse, and that even the traguloid forms are of tylopodous 
affinity and merely parallel or analogous to the true Tragu- 
lines of Eurasia. There is no doubt that such an adaptive 
radiation from a Tylopod stem is possible and that there 
is considerable actual evidence for it in the morphology of 
the skull of these various distinctively American Artio- 
dactyls ; but the hypothesis is such a bold one that we must 
wait for more material. 
The chief problem of all, which is also the problem 
of the European palaeontologists, is the source and origin 
of the modern Lower Eocene fauna as a whole, namely., the 
Carnivora, Perissodactyla, Artiodactyla, Primates, and Ro- 
dentia. 
American Oligocene Faunas 
Our Oligocene (Lower Oligocene Infra-Tongrien. Mid- 
dle Stampien, and Upper Aquitanien, of Europe) has been 
the most thoroughly explored of any of the periods, owing 
to the richness of its fossil fauna. 
The chief geological result is the separation of the 
4 The Selenodont Artiodactyles o f the Uinta Eocene; Trans. W'agner 
Free Inst. Sci. Phil., vi, 1899, p. 100. 
