THE OX AND ITS KINDRED 
nature of the relationship of oxen to antelopes must 
remain an open question. 
The genealogy, or family tree," of the ox, in com- 
mon with the other members of the Bovidce^ is much 
less well known than is that of the horse and its 
relatives. In the opinion of the late Professor Carl 
Zittel/ of Zurich, one of the greatest authorities on 
fossil mammals, both the hollow-horned ruminants 
and deer are descendants of primitive animals from the 
middle and lower (Oligocene and Eocene) Tertiary 
rocks of Europe more or less nearly allied to the 
modern chevrotains, and included in the same family, 
that is to say, the Tragulidce. The genus which 
probably formed the ancestral stock is known by 
the name of Gelocus, and includes small chevrotain- 
like ruminants, in which the radius and ulna in the 
fore, and the tibia and fibula in the hind, leg are 
complete and separate ; but the navicular and cuboid 
bones of the ankle, or tarsus, are fused together, as 
in the typical ruminants. On the other hand, the 
main pair of metacarpal bones in the fore-limb 
remain separate, but in the hind-limb the correspond- 
ing metatarsals may either be separate or may 
amalgamate into a cannon-bone, the former condi- 
tion obtaining in one species, and the latter in a 
second. The lateral pair of metacarpals and of meta- 
tarsals are represented by splint-like remnants of both 
their upper and lower extremities. An allied Oligocene 
genus, Pi'odremotherium, has complete cannon-bones 
in both limbs, and thus serves to connect Gelocus with 
the modern chevrotains. The former genus is known 
to have lacked upper incisors, but whether these teeth 
^ " Handbuch der Palseontologie, — Mammalia," Munich and Leipsic, 
1891-1893, p. 324. 
