108 
ORIGIN OF LIFE IN AMERICA 
and it differs in other fundamental characters from the mule 
deer, which has apparently no near relations in the Old World, 
and which we may justly call the true American deer. 
Fossil remains of the mule-deer have been found in the 
Conard Fissure.* The fossil bones of other deer from the 
Pleistocene of Illinois, Iowa, Wisconsin and Indiana, have 
been referred to extinct species of the genus Odocoileus to 
which the mule-deer belongs. No Pliocene or older traces 
of this genus have as yet been discovered in North America, 
if we adopt the generally accepted view of the Conard Fissure 
being of Pleistocene age. Altogether there are three fairly 
distinct species of the type of the mule-deer in North America, 
namely the one I have just described, the white-tailed deer 
(Odocoileus virginianus) and the black-tailed Columbian deer 
(0. columbianus). 
It is of considerable interest to know that this genus lives 
not only in Central America, but right to the southern ex 1 - 
tremity of South America in Chile. This fact alone is remark¬ 
able, for nowhere else in the world are deer found south of the 
Equator. They are entirely absent from Africa and Australia. 
However, it is by no means the only noteworthy circumstance 
about this American group of deer. Those who are ac¬ 
quainted with the habits and life history of the deer tribe 
know that the young of deer with large branching antlers 
at first possess no antlers. Afterwards small, simple and 
unbranched processes appear on their heads. From year 
to year they are shed and new ones take their place, and these 
are always a little more complex than the previous ones. The 
gradual development of the race seems to follow that of the 
individual. It is only in the more recent geological periods 
that deer with branching antlers make their appearance. As 
we go back to earlier deposits the deer skulls only bear simple 
antlers with one or two branches. In still older strata we 
meet with deer that were devoid of antlers, while they gene¬ 
rally possessed long canine teeth which no doubt were useful 
as organs of defence. It has been rightly argued that the 
complex antlers have only been developed in comparatively 
recent geological times, and that deer with simple antlers 
Brown, Barnurn, “Conard Fissure,” p. 205, 
