422 THE AMERICAN NATURALIST. [Voı. XXXIX. 
mentum nucha and the huge muscles which supported the 
skull. Neither the rhinoceroses nor the elephants exhibit such 
a development as this and one is reminded irresistibly of the 
bisons in which the head becomes an offensive weapon of great 
power. Certainly this development implies more than the mere 
passive support of the head and is probably directly correlated 
with the development of the cranial armature. 

Fic 
Museum. 
2.— Anterior 
view of the skull of Megacerops, from a specimen in the Amherst College 
Rhinoceroses charge their enemies, using the nasal horn with 
good eitect, and here again there seems to be a direct relation- 
= D At ureon » ge ý 
ship between the height and power of the shoulders and the 
>oree of devel. ee i 
degree of development of the horns. In the rhinoceros, how- 
