There still remains one feature in the psychology of talking birds to which I must now draw prominent attention. So far as I can ascertain it has not been mentioned by any previous writer, although I should think it is one that can scarcely have escaped the notice of any attentive observer of these animals. I allude to the aptitude which intelligent parrots display of extending their articulate signs from one object, quality, or action, to another which happens to be strikingly similar in kind. For example, one of the parrots which I kept under observation in my own house learnt to imitate the barking of a terrier, which also lived in the house. After a time this barking was used by the parrot as a denotative sound, or proper name, for the terrier—_i.e._ whenever the bird saw the dog it used to bark, whether or not the dog did so. Next, the parrot ceased to apply this denotative name to that particular dog, but invariably did so to any other, or unfamiliar, dog which visited the house. Now, the fact that the parrot ceased to bark when it saw my terrier after it had begun to bark when it saw other dogs, clearly showed that it distinguished between individual dogs, while receptually perceiving their class resemblance. In other words, the parrot’s name for an individual dog became extended into a generic name for all dogs. Observations of this kind might no doubt have been largely multiplied, if observers had thought it worth while to record such apparently trivial facts. * * * * * In this general survey of articulate language, then, we have reached these conclusions, all of which I take to be established by the evidence of direct and adequate observation. There are four divisions of the faculty of articulate sign-making to be distinguished:—namely, meaningless imitation, instinctive articulation, understanding words irrespective of tones, and intentional use of words as signs. Cases falling under the first division do not require consideration. Cases belonging to the second, being due to hereditary influence, occur only in infants, uneducated deaf-mutes and idiots. Understanding of words is shown by animals and idiots as well as by infants, and implies, _per se_, a higher development of the sign-making faculty than does the understanding of tones, or gestures—unless, of course, the latter happen to be of as purely conventional a character as words. And, lastly, concerning the intentional use of words as signs, we have noticed the following facts.