Fig. 263.—Aye-aye. Chiromys madagascariensis. × 1⁄10.
Fam. 2. Chiromyidae.—This family contains but a single genus and species, the Aye-aye, Chiromys madagascariensis, whose characters therefore are for the present those of the family as well as of the genus and species. The external features of this extraordinary animal will be gathered from an inspection of Fig. 263, from which it will be seen that the earlier name of Sciurus given to the creature was not by any means a misnomer. The Squirrel-like appearance is due, of course, chiefly to the strong and long incisor teeth. As to the external characters, which are of systematic importance,
attention may be called to the long and bushy tail, to the greater length of the hind-limbs, to the abdominal teats (one pair) in the female, and above all to the singular third digit of the hand, which is thin and elongated. The thumb is, as in other Lemurs, opposable, and has a flat nail; the remaining digits have claws, as have also the toes with the exception of the great toe, which has a flat nail like the thumb.
The anatomy of this animal has occupied the attention of a considerable number of observers, dating from Sir R. Owen, who was the first to give a connected account of its entire organisation. The most recent paper of importance is by Dr. Oudemans.[[409]] The teeth are very unlike those of other Lemurs. The most remarkable divergence is in the incisors, which are present to the number of but a single pair in each jaw, and are shaped like those of the Rodentia, and in the same way as in that group grow from persistent pulps. There are likewise, as in the Rodents, no canines. There are two premolars in the upper jaw (none in the lower) and altogether twelve molars, so that there is a total of eighteen teeth. The intestine has a moderately long caecum. The brain has been most fully described by Oudemans, who had fresh material to work with, the brain described by Owen having been extracted from a spirit-preserved carcase. The angular fissure is well developed, as in Lemur and the Indri; but it does not join the infero-frontal. The antero-temporal fissure is also well developed.
"The name of Aye-aye," wrote Sonnerat, the discoverer of the animal, "which I have retained for it, is a cry of surprise of the inhabitants of Madagascar." It is, however, usually said that the animal itself makes a sound which may be written in the same way (or with an initial H). It is an arboreal and nocturnal animal, which accounts for its excessive rarity at one time. In one of his many eloquent essays upon natural history the late Mr. P. H. Gosse adduced the Aye-aye as an example of a creature on the verge of extinction. It is, however, now more frequently met with, though the superstition of the natives renders its capture a matter of some difficulty. There is a specimen at the moment of writing in the Zoological Society's Gardens. There has been some discussion as to the use of the slender middle finger: it is stated that it can thrust it into the
borings of the larva of a certain beetle of which the Lemur is particularly fond, and can extract the insect, or at any rate discover its position, when it may be extracted by the powerful chisel-shaped teeth. The partiality of the Aye-aye for animal food of any kind including insects has been both reaffirmed and denied; and Mr. Bartlett has seen the creature use its slender finger for combing out its hair, and for other purposes of the "toilet." Dr. Oudemans has figured in his paper an apple which has been largely eaten by the Chiromys; the fleshy pulp has been entirely excavated, leaving only the core and the skin, which are untouched. The Rev. Mr. Baron is one of the latest writers upon the ways of life of Chiromys.[[410]] He states that it inhabits the most dense parts of the forests. It has the habit of prowling about in pairs, and the female produces but a single young one at a birth. A nest, which is about 2 feet across, is made of twigs in lofty branches. This is occupied during the day, and entered by a hole in the side. With regard to the superstitious veneration in which the animal is held, it is said that if a person sleeps in the forest the Aye-aye will bring him a pillow. "If a pillow for the head, the person will become rich; if for the feet, he will shortly succumb to the creature's fatal power, or at least will become bewitched." But a counter-charm may be obtained. It is said that the reverence for this beast leads the natives to bury carefully a specimen found dead.
Fam. 3. Tarsiidae.—This family also consists of but a single genus, Tarsius, to which it is the general opinion that but a single species belongs; there are, however, at least four different specific names on record. The general aspect of the animal is not unlike that of a Galago, with which it also agrees in the elongation of the ankle; but the elongation is more pronounced in the present genus. The ears are large, and the eyes are extraordinarily developed. The fingers and toes terminate in large expanded discs, and are furnished with flattened nails except on the second and third toes, which have claws. The tail is longer than the body and is tufted at the end. The skull is more like that of the Anthropoidea than is the skull of any other Lemur. The resemblance is by reason of the almost complete separation of the orbit and the temporal fossa by bone;
there is, however, a gap left to mark the Lemurine characters of the animal. The placenta, too, has been compared to that of the Apes. The dental formula is that of the genus Lemur, save for the absence of an incisor on each side of the lower jaw; the number of teeth is therefore thirty-four. The incisors of the lower jaw are upright, and not procumbent as in other Lemurs. The caecum is of moderate length. The brain is almost smooth, but there is a Sylvian fissure and an antero-temporal, which latter does not reach the lower margin of the brain, but divides the middle part of the temporal lobe. The name Tarsier, as may be inferred, was originally given to this creature by Buffon on account of the abnormal ankle, and it was compared by him with the Jerboa, like which animal the Tarsier leaps when it descends to the ground. The genus is Malayan, but its range extends to the Philippines and to Celebes and Borneo. The Tarsiers are nocturnal and particularly arboreal; they live in pairs, in holes in tree stems, and are mainly insectivorous in their food. One, rarely two young are produced at a birth. Contrary to what is found in many Lemurs, the Tarsier is a silent creature, and at most emits a "sharp, shrill call." Dr. Charles Hose, who has studied this creature, has noticed that the mother often carries her young one about in her mouth like a Cat. Like so many Lemurs this animal is held in superstitious dread, which no doubt is the result of its most weird appearance.[[411]]
Fig. 264.—Right pes of Tarsius spectrum. (Nat. size.) a, Astragalus; c, calcaneum; c1, internal cuneiform; c2, middle cuneiform; c3, external cuneiform; cb, cuboid; n, navicular; I-V, the digits. (From Flower's Osteology.)