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lemurs is that certain species (Opolemur samati, Chirogale milii, &c.) during the dry season coil themselves up in holes of trees, and pass into a state of torpidity, like that of the hibernating animals in the winter of northern climates. Before this takes place an immense deposit of fat accumulates upon certain parts of the body, especially the basal portion of the tail. The smallest species, M. pusillus, lives among the slender branches on the tops of the highest trees, feeding on fruit and insects, and making nests like those of birds.

In the sub-family Indrisinae the dentition of the adult consists of thirty teeth, usually expressed by the formula i. 2/1, c. 1/1, p. 2/2, m. 3/3; but possibly i. 3/2, c. 1/0, p. 3/2, m. 3/3. In the milk-dentition there are twenty-two teeth, the two additional teeth in the fore part of the lower jaw having no successors in the permanent series. Hind limbs greatly developed, but the tarsus normal, the great toe of large size, and very opposable; the other toes united at their base by a fold of skin, which extends as far as the end of the first phalange. The thumb is but slightly opposable; and all the fingers and toes are hairy. The length of the tail is variable. Two pectoral teats. Caecum very large, and colon extremely long and spirally coiled. The brain is large and the thorax wide.

(From Milne-Edwards and Grandidier.)

Fig. 20.—The Indri (Indris brevicaudatus).

The animals of this group are essentially arboreal, and feed exclusively on fruit, leaves, buds and flowers. When they descend to the ground, which is but seldom, they sit upright on their hind legs, and move from one clump of trees to another by a series of short jumps, holding their arms above them in the air. Among them are the largest members of the order. The genus Indris has the upper incisors sub-equal in size; upper canine larger than the first premolar, muzzle moderately long, ears exserted. Carpus without an os centrale. Tail rudimentary. Vertebrae: C.7, D.12, L.9, S.4, Ca.9. The indri (I. brevricaudatus, fig. 20), discovered by Sonnerat in 1780, is the largest of the group, and has long woolly hair, partly brown and partly white. In the sifakas, Propithecus, of which there appear to be three species, with numerous local races, the second upper incisor is much smaller than the first. Upper canine larger than the first premolar. Muzzle rather short. Ears short, concealed by the fur. An os centrale in the carpus. Tail long. Vertebrae: C.7, D.12, L.8, S.3, Ca.28. In Avahis, represented only by A. laniger, the second upper incisor is larger than the first. Upper canine scarcely larger than the first premolar. Muzzle very short. Ears very small and hidden in the fur, which is very short and woolly. Carpus without os centrale. Tail long. Vertebrae: C.7, D.11, L.9, S.3, Ca.23 (see Indri and Sifaka).

The last sub-family, Chiromyinae (formerly regarded as a family), is represented only by the aye-aye, Chiromys (or Daubentonia) madagascariensis, and has the following characteristics: Dentition of adult, i. 1/1, c. 0/0, p. 1/0, m. 3/2, total 18. Incisors (fig. 21) very large, compressed, curved, with persistent pulps and enamel only in front, as in rodents. Teeth of cheek-series with flat indistinctly tuberculated crowns. In the young, the first set of teeth more resemble those of normal lemurs, being i. 2/2, c. 1/0, m. 2/2, all very small. Four teats, inguinal in position, a feature peculiar to this species. All the digits of both feet with pointed, rather compressed claws, except the great toe, which has a flattened nail; middle digit of the hand excessively attenuated. Vertebrae: C.7, D.12, L.6, S.3, Ca.27 (see Aye-Aye).

Fig. 21.—Skull of the Aye-aye (Chiromys madagascariensis).

(From A. Milne-Edwards.)

Fig. 22.—The Slow Loris (Nycticebus tardigradus).

Galagos and Lorises.—The lemurs of Africa and the Indo-Malay countries-commonly miscalled sloths—differ from the Lemuridae in that the tympanic enters into the formation of the auditory meatus, in consequence of which they are referred to a family by themselves, the Nycticebidae, which is in turn divided into two sub-families, Galaginae and Nycticebinae. The African galagos or Galaginae, which have the same dental formula as the Lemuridae, are distinguished by the elongation of the calcaneum and navicular of the tarsus. In the single genus Galago, with the sub-genera Otolemur and Hemigalago, the last upper premolar, which is nearly as large as the first molar, has two large external cusps. Vertebrae: C.7, D.13, L.6, 5.3, Ca.22-26. Tail long, and generally bushy. Ears large, rounded, naked and capable of being folded at the will of the animal. Teats four, two pectoral and two inguinal (see Galago). The lorises, Nycticebinae (Lorisinae), are distinguished as follows: Index-finger very short, sometimes rudimentary and nailless. Fore and hind limbs nearly equal in length. Tarsus not specially elongated. Thumb and great toe diverging widely from the other digits, the latter especially being habitually directed backwards. Tail short or rudimentary. Teats two or four. Lorises and pottos (as the African representatives of the group are called) are essentially nocturnal, and remarkable for the slowness of their movements. They are completely arboreal, their limbs being formed only for climbing and clinging to branches, not for jumping or running. They have rounded heads, very large eyes, short ears and thick, short, soft fur. They feed, not only on vegetable substances, but, like many of the Lemuridae, also on insects, eggs and birds, which they steal upon while roosting at night. One of the greatest anatomical peculiarities of these animals is the breaking up of the large arterial trunks of the limbs into numerous small parallel branches, constituting a rete mirabile, which is found also in the sloths, with which the lorises are sometimes confounded on account of the slowness of their movements. The Asiatic lorises, which are divided into two genera, are characterized by the retention of the normal number of phalanges in the small index-finger, and the presence of a pair of minute abdominal teats (the existence of which has only recently been discovered by Messrs Annandale and Willey). In the slow lorises, forming the genus Nycticebus (fig. 22), the first upper incisor is larger than the second, which is often early deciduous. Inner margin of the orbits separated from each other by a narrow flat space. Nasal and