202 NEW YORK ZOOLOGICAL SOCIETY. 
Rockies ; and, third, the Columbia black-tailed deer of the Pacific 
coast, O. columbianus, with its outlying subspecies in the North, 
the Sitka deer, O. c. sitkensis. 
The genus Odocoileus departs widely from all the Old World 
types. Its closest allies, as far as foot structure is concerned, are 
Alces and Rangifer. 
These American deer have been on this continent for a very 
long time, possibly as far back as the Miocene. They have spread 
throughout both North and South America, and have developed 
many well-defined species, both facts indicating a long period of 
radiation on this continent. The antlers of Odocoileus cannot be 
in any way correlated with those of any other genus of the deer 
family, least of all with those of Cervus. 
All the members of the Cervidae sprang originally from the 
same stock, but this ancestral form was either hornless, or else 
had a simple spike, with, at most, a single branch, resembling the 
dag-antler of the yearling. This spike-horn ancestor is probably 
the correct explanation, as otherwise it is necessary to assume 
that the different members of the deer family acquired the ex- 
traordinary character of deciduous antlers independently, and to 
find a common ancestor we should have to go back to a hornless 
cervine, resembling the existing musk-deer or the Chinese water 
deer. 
A Miocene group of ruminants found in North America, 
which has heretofore been considered as possibly ancestral both 
to Odocoileus and Antilocapra, proves, on close investigation, to 
be a new and separate family, or at least a clearly defined subfam- 
ily of the Bovidae. This group includes Cosoryx, Blastomeryx 
and Merycodus. 
These merycodonts are practically antlered antelopes, being in 
foot structure, the high molar crowns, and in other char- 
acters, close to the bovine antelopes, and still closer to Antilo- 
capra, and, were it not for the antlers, they might be considered 
ancestral to the latter. In this affinity to the prong-horns they 
suggest an American ancestry for that animal. 
Paleomeryx, however, is a true deer, and is found both in the 
American Miocene and in the European Oligocene. It is a gen- 
eralized cervine. The American forms had unbranched antlers, 
situated directly over the eye, apparently with permanent velvet, 
and without a burr, suggesting in these respects the giraffe. The 
European forms, however, although earlier, were much more spe- 
cialized, and had both a burr and naked antlers, with a single 
prong. 
