Chap. 112.] DIFEEEENT VOICES OE AJTIMALS. 
93 
with tlie exception of man and the ape, have tails in propor- 
tion to the necessities of the body. In animals with bristles 
the tail is bare, as in the boar, for instance. In those that are 
shaggy, it is small, such as the bear ; while in those animals 
that have long hair, the tail is long also, the horse, for in- 
stance. The tail of a lizard or serpent, if cut off, will grow 
again. The tail governs the movements of the fish like a 
rudder, and turning from side to side, to the right or to the 
left, impels it onwards, acting in some degree like an oar. 
A double tail is sometimes found in lizards. In oxen, the 
stalk of the tail is of remarkable length, and is covered with 
rough hair at the extremity. In the ass, too, it is longer than 
in the horse, but in beasts of burden it is covered with bristly 
hairs. The tail of the lion, at the extremity, is like that of 
the ox and the field-mouse ; but this is not the case with the 
panther. In the fox and the wolf it is covered with long 
hair, as in sheep, in which it is longer also. In swine, the 
tail is curled ; among dogs, those that are mongrels carry it 
close beneath the belly. 
CHAP. 112. (51.) — THE DIEFEKENT VOICES OF AKIMALS. 
Aristotle is of opinion that no animal has a voice which 
does not respire, and that hence it is that there is no voice in 
insects, but only a noise, through the circulation of the air in 
the interior, and its resounding, by reason of its compression. 
Some insects, again, he says, emit a sort of humming noise, 
such as the bee, for instance ; others a shrill, long-drawn note, 
like the grasshopper, the two cavities beneath the thorax re- 
ceiving the air, which, meeting a moveable membrane within, 
emits a sound by the attrition. — Also that flies, bees, and 
other insects of that nature, are only heard while they are 
flying, and cease to be heard the moment they settle, and that 
the sound which they emit proceeds from the friction and the 
air within them, and not from any act of respiration. At aU 
events, it is generally believed that the locust emits a sound 
by rubbing together the wings and thighs, and that among 
the aquatic animals the scallop makes a certain noise as it 
flies.^^ Mollusks, however, and the testaceous animals have no 
voice and emit no sounds. As for the other fishes, although 
52 Hist. Anim. B. iv. c. 9. , 53 gge B. ix. c. 52. 
