144: SPECIAL EXPRESSIONS: CHAP. V. mankind hardly any expression is more general than a widely open mouth under the sense of astonishment. As far as I have been ahle to observe, monkeys breathe more freely through their nostrils than men do; and this may account for their not opening their months when they are astonished: for, as we shall see in a future chapter, man apparently acts in this manner when startled, at first for the sake of quickly drawing a full inspiration, and afterwards for the sake of breathing as quietly as possible. Terror is expressed by many kinds of monkeys by the utterance of shrill screams; the lips being drawn, back, so that the teeth are exposed. The hair becomes erect, especially when some anger is likewise felt. Mr. Sutton has distinctly seen the face of the Macacus rhesus grow pale from fear. Monkeys also tremble from fear; and sometimes they void their excretions. I have-seen one which., when caught, almost fainted from an excess of terror. Sufficient facts have now been given with respect to the expressions of various animals. It is impossible to agree with Sir C. Bell when he says -- that " the faces of animals seem chiefly capable of expressing rage and fear; " and again, when he says that all their expressions " may be referred, more or less plainly, to their acts of volition or necessary instincts." He who will look at a dog preparing to attack another dog or a man, and at the same animal when caressing his master, or will watch, the countenance of a monkey when insulted, and when fondled by his keeper, will be forced to admit that the movements of their features and their gestures are almost as expressive as those of man. Although no explanation a ' Anatomy of Expression,' 3rd edit. 1844, pp. 138, 121.