The Artiodactyla. 
133 
Each of the genetic series commences with a genus with no 
or with very simple horns. The next genus or stage presents 
branched horns, sometimes of great complexity. The last term 
in each is the palmate horn, where a greater or less number of 
the tines unite to form a plate. These series, as is well known, 
correspond with the history of the growth of the horns in 
successive years of the life of each species. (Fig. 21.) 
None of the genera of this family are extinct except Cer- 
valces Scott. 
The true Cervidae form a family of very recent origin, and 
only distinguished at the period when forms like Cosoryx and 
~ began to shed their horns. 
ented by several species in the middle Miocene of Europe, 
nd their horns are mostly bifurcate as in the third year's horn 
fa true deer. In the middle Miocene and part of the Plio- 
ene the horns have three antlers as in the fourth year of 
perman 
I the 
genu 
I of 
tropical Asia 
The many branched horns appear in the Pliocene and Plisto- 
Cervidse are more abundant than Bovidae. Several species 
occur in the Pliocene beds of Buenos Ayres, and of Washing- 
ton. The latter are related to the Moose {Alces brevitrabalis 
Cope) and American deer, {Cariacus ensifer Cope.) A very 
