THE DIADEM INDRIS.[116]
DIADEM INDRIS AND WOOLLY INDRIS. (After Grandidier.)
This is a fine species, with a white furry ruff, or crown, on the forehead and around the face, and it has a long muzzle and body, and a thick, long tail. It greatly resembles the White Indris, called Sifac, with the exception of its characteristic head ornament, and leads the same kind of life in another part of the island of Madagascar. Fine stuffed specimens of it, and of many other Indrisinæ, are in the British Museum, and it will be noticed that they are there called, not Indris, but Propithecus, which is another name for them. It is a question of the value of a tail in classification, which produces the two names for one genus. Some zoologists are impressed with the great importance of the tail, and do not class species together as a genus, although they may have strong resemblances, unless they all have or have not tails. Others do not consider the possession of a tail to be of such great importance when the other characters are sufficiently close to render it advisable to form them into one group. The same question arose in considering the Monkeys, for in the genus Macacus we admitted Macaques with and without tails; and also in the genus Cynocephalus, in which there are some with good, others with small, and a few with very stumpy tails, the same caudal latitude was given. Hence, it is not consistent to form two genera of these creatures, one with a tail (or Propithecus) and the other without one, or with a stump (or Indris). Indris contains the Lemuroids, whose other resemblances are so great that they overweigh the tail question. So little is known about the Diadem Indris that it is only necessary to notice one point in its anatomy, which refers to its habits. It evidently assumes the semi-erect posture very frequently when climbing, and a great part of the weight of the body is felt by the foot and its great clasping toe-thumb. The examination of the foot proves that it is one, and not a hand, for bone for bone it may be compared with the human foot, and that of the Apes. The great toe is wide apart from the others, and in that it resembles the thumb of a hand; but all the other bones of the ankle or tarsus are in the same relative position as they occupy in us. They have the same names. Their foot is very broad, and this is produced by the extra size of the four front bones of the ankle, and these form an arch, the three inner ones being more or less wedge-shaped, and the outer, or fourth, is more or less of a cube in shape; hence they are called the wedge-shaped (cuneiform) and cube-shaped (or cuboid) bones. They are jointed in front to the long bones (metatarsals), and behind to the three other ankle-bones. All are united more or less solidly by ligaments, and yet there is motion. Now in this Indris the wedge-shaped bones are large, especially the second from the inside, or the middle one, and curiously enough this is small in most other Lemuroids. The large arch formed by these bones contributes to the strength of the foot.
BLACK OR SHORT-TAILED INDRIS. (Modified after Grandidier.)
The Diadem Indris is found in the forests of the central parts of Madagascar, and appears to keep apart from other kinds and to roam about the dense woods in bands.
THE WOOLLY LEMUR—THE AVAHI.[117]
This is one of the long-tailed Indris, and is remarkable for having long hinder limbs, a long furry tail, a very short muzzle, and a round head.
It was first described by Sonnerat, in his voyage to the East Indies, who called it the Makis à bourre, or the Woolly Makis. On the north-east coast, the natives call this Indris the Amponghi, and this name is given to it in the great forest of Tsasifoutt, which is in the island of St. Mary, adjacent to Madagascar. This is an interesting point, for it affords evidence that the island of Madagascar had once a greater geographical extension, and that St. Mary’s and the other small islands along the coast were at a former period continuous with it. These woolly Indris are not frequently caught, or indeed seen at all, for they hide during the daytime, and sleep curled up amongst the thick shade of the foliage, or in some comfortable nest in the hollow of a tree. At night-time they wake up, and eat and play amongst the trees on which their food grows. They are said to be stupid animals, but probably, as they have never had their intelligence tested except when half asleep, they may be quite as intelligent as the other Lemuroids, and this opinion is strengthened by the fact that the brain of the Indris laniger is large in proportion to the size of the body; larger indeed in proportion than the brain of any of the others. It is this relative size of the great organ of the nervous system which has impressed some zoologists with the propriety of placing this Indris at the head of all the Lemuroids, and nearest the Monkeys.