1889.1 The Artiodactyla. 127 
displays the parietal extremely reduced, and become chiefly 
lateral in position. As regards the forms of the horns them- 
selves, they present no important differences, but are angular 
and revolute in the section Ovis, and cylindric in the division 
Antilope. In the latter they vary in direction from straight 
to spiral or curved in different directions. Within the genus 
Ovis the end of the muzzle is naked or hairy, the latter in the 
typical forms and in those inhabiting northern and alpine 
localities generally. Those species that inhabit grassy or 
desert plains have the end of the nose naked. 
Within the genus Bos modifications are observed parallel 
to those in the genus Ovis. The frontal bones with the horn 
processes are produced more and more posteriorly until the 
parietal bones are reduced to a narrow band across the pos- 
terior part of the skull. The bisons have the horns most 
anterior ; then follow the buffalos, and the extreme is reached 
in the true oxen, of which the domesticated animal is the 
type. 
The following table will give an idea of the phylogeny of 
the Bovidae. 
1/ 
Palaeomeryx 
The hornless Palaeomeryx has given origin to the horned 
Booidea ; on the one hand to the brachyodont (Blastomeryx, 
etc.), and on the other to the hypsodonts (Cosoryx, etc.). A 
cornification of the integument in a fork horned Cosoryx 
produced Antilocapra, while the same process in a simple- 
horned Cosoryx, produced Ovis. The development of this type 
has undergone the three principal modifications indicated by 
the three genera which succeed upwards. In Saega an extra- 
