The Artiodactyla 
From Tich- 
portion having disappeared (fig. 8-5). The median pair are 
united into a cannon bone. There are no superior incisors. 
The odontoid process of the axis vertebra is trough-shaped. 
The stomach is divided into four parts. 
The lowest family of the series is that of the Moschid^. In 
its hard parts it differs from the Bovidae in the simplicity 
of the anterior third superior premolar, which is without 
the internal crescent found in the other Booidea. In this 
respect it is intermediate between that division and the Cam- 
eloidea, where the first premolar only possesses the internal 
crescent. But two genera of Moschidae are known, Dremothe- 
rium from the Lower Miocene of France, and the living Mos- 
chus. Both lack horns and have well developed canine 
teeth. The origin of this group is clearly from the Tragulidae, 
and the genus of that family which approaches nearest to it 
IS Amphitragulus, which indeed only differs from it in den- 
tition in the imperfection of the internal crest of the second 
superior premolar. In turn, Dremotherium must be regarded 
as ancestral to Palaeomeryx, the most primitive genus of the 
The Giraffid^ differ ( see table of families ) in the mode of 
attachment of the horns. These are originally separate from 
the skull, but become attached to it Hke the epiphyses on the 
extremities of the" bones of the skeleton. Their dental char- 
acters are Hke those of the Cervidae and the lower Bovidae, 
the molars being short crowned or brachyodont. It may be 
that the condition of the horns in Girafifa represents the mode 
of origin of the horns of the Bovidae,' and that the genus is 
simply to be reckoned a primitive type in that family. The 
' In the sheep the horns begin as bodies separate from the skull. 
