THE NERVOUS SYSTEM. 187 
traction of the vocalizing muscles, except in the very act 
of vocalization. The vocal sounds produced by Mammals 
may be distinguished into the ordinary voice, the ery, and 
the song. The second is the sound made 
by brutes. The Whale, Porpoise, Armadil- 
lo, Ant-eater, Porcupine, and Giraffe are 
generally silent. The Bat’s voice is prob- 
ably the shrillest sound audible to human 
ears. There is little modulation in brute 
utterance. The Opossum purrs, the Sloth 
and Kangaroo moan, the Hog grunts or : 
squeals, the Tapir whistles, the Stag bel- Tania sea 
lows, and the Elephant gives a hoarse trump- pF"in? “ysia 
et sound from its trunk and a deep groan aa ; aa 
from its throat. All sheep have a guttural gauss) eplelay 
voice; all the Cows low, from the Bison to 
the Musk-ox; all the Horses and Donkeys neigh; all the 
Cats miau, from the domestic animal to the Lion; all the 
Bears growl; and all the Canine family—Fox, Wolf, and 
Dog—bark or howl. The Howling-monkeys and Goril- 
las have a large cavity, or sac, in the throat for resonance, 
enabling them to utter a powerful voice; and one of the 
Gibbon-apes has the remarkable power of emitting a com- 
plete octave of musical notes. The human voice, taking 
the male and female together, has a range of nearly four 
octaves. Man’s power of speech, or the utterance of artic- 
ulate sounds, is due to his intellectual development rath- 
er than to any structural difference between him and the 
Apes. Song is produced by the glottis, speech by the 
mouth. 
