MEANS OF EXPRESSION IN ANIMALS. CHAP. IV. have moveahle ears, and which fight with their teeth — for instance the Gercopitliecus nibei — draw back their cars when irritated just like dogs; and they then have a very spiteful appearance. Other kinds,, as the Inuus ecaudatus, apparently do not thus act. Again,, other kinds — and this is a great anomaly in comparison with most other animals — retract their ears, show their teeth, and jabber, when they are pleased by being caressed. I observed this in two or three species of Macacus, and in the Qynopitliecus niyer. This expression, owing to our familiarity with dogs, would never be recognized as one of joy or pleasure by those unacquainted with monkeys. Erection of the Ears. — This movement requires hard- ly any notice. All animals which have the power of freely moving their ears, when they are startled, or when they closely observe any object, direct their ears to the point towards which they are looking, in order to hear any sound from this quarter. At the same time they generally raise their heads, as all their organs of sense are there situated, and some of the smaller animals rise on their hind-legs. Even those kinds which squat on the ground' or instantly flee away to avoid danger, gen- erally act momentarily in this manner, in order to ascer- tain the source and nature of the clanger. The head being raised, with erected ears and eyes directed for- wards, gives an unmistakable expression of close atten- tion to any animal.