The word “petaurista” is the Latin for “one that showeth tricks of activity, from a machine suspended,” according to old dictionaries, so this Monkey with a white nose has its abilities properly designated. Some call it the Vaulting Monkey, but in the Zoological Gardens its wonderful agility is shown by its scampering up the side, over the top, and down the opposite side of its cage in a kind of continuous somersault. Coming down on all-fours with a bang, it does the same thing over and over again to attract attention, and it seems as if it were moving in the inside of a wheel. The dab of white on the nose distinguishes it, and it comes from that paradise of Monkeys the Guinea Coast and the adjoining districts. The only one of the second group to be mentioned is THE TALAPOIN.[43] This is a rather rare animal, and comes from the west coast of Africa, having been sent to Europe from the Gaboon. It is a pretty little creature (probably the smallest of these Monkeys), and is extremely gentle and intelligent. The skin is green, and the lower part of the body and the under part of the limbs are white. It has large ears, a black nose, and it has a kind of broad “brutus” on the forehead. There are some very interesting points about this little thing, which, in nearly all its construction, is like the rest of the Cercopitheci, or Guenons, but it has a large brain, a short muzzle, a thick, long partition in its nose, and only three points, or cusps, instead of four, on its last lower hind grinders. [Illustration: HEAD AND SHOULDERS OF THE TALAPOIN.] So far as is known, there are no differences between the habits of this little Monkey and the others from the west coast of Africa, and therefore its intelligence and deficiencies are sufficiently incomprehensible; but they exhibit a fact of great importance, of which a hint was given in the conclusion of the description of the Mona Monkey. In the Talapoin, the last lower grinder differs from that of all Monkeys by the absence of an important part of its usual structure, and in the Mona the great air sac, which is in communication with the windpipe in most other Monkeys, is absent. This fact may be stated as follows:--That in animals closely resembling others of their group or genus material deficiencies in construction suddenly appear. Corresponding to these deficiencies are the absence of all or a great part of tail in genera the majority of whose species have a tail, and the inference to be drawn is that, notwithstanding all the members or species of a genus are related by a common ancestry, the descendants of a well-marked stock may exhibit peculiarities of structure which are not produced by alterations in the habits or surroundings of the animals. Such peculiar structures often relate to a remote ancestor, and it is remarkable that in the case of this Talapoin they give it a very faint resemblance to the American Monkeys.