128 
The An 
Naturalist. 
[March. 
ordinary^ development of the muzzle takes place, which causes 
a change in the relations of the nasal bones. In Tetracerus 
another pair of horns is developed in front of the usual pair. 
Bos developes complications of the molar teeth in both 
On the brachyodont side the development of the dermal 
overing^ of the horns of Blastomeryx is arrested, and naked 
orned types follow. In the Sivatheriine group no further 
