Part 9

Lemur tardigradus, Linn., S. N., i., p. 44 (1766, pt.).

Nycticebus bengalensis, Geoffr., Ann. Mus., xix., p. 164 (1812).

Nycticebus javanicus, Geoffr., t. c. p. 164 (1812); id. Cat. Primates, p. 78 (1851); Schl., Mus. Pays Bas, vii., p. 286 (1876).

Nycticebus tardigradus, Fischer, Syn. Mamm., p. 71, no. 2 (1829); Is. Geoffr., Cat. Méth. Primates, p. 78 (1851); Blyth, Cat. Mam. As. Soc., p. 18 (1863); Schl., Mus. Pays Bas, vii., p. 285 (1876); Anderson, Cat. Mamm. Ind. Mus., p. 94 (1881); Blanf., Faun. Brit. Ind. Mamm., p. 44 (1888).

Stenops tardigradus, Van der Hoeven, Tijdschr. Nat. Ges., xi., p. 39 (1844); Wagner in Schreb., Säug. Suppl., v., p. 151 (1855).

Stenops javanicus, Van der Hoeven, op. cit., p. 40 (1844); Wagner, op. cit., p. 152 (1855).

Nycticebus cinereus, Milne-Edw., Ann. Mus., vii., p. 161 (1867); id. N. Arch. Mus., iii., p. 9, pl. 3 (1867); Anderson, Rep. Zool., Yun-nan, p. 103 (1879); Schl., Mus. Pays Bas, vii., p. 286 (1876).

Lemur menagensis, Nachtrieb, Zool. Anz., xv., p. 147 (1892).

(Plate III.)

CHARACTERS.--Body larger and fuller than in Loris, and covered {34}with close and woolly fur. Head short and round. Eyes large, set close together, and having a gentle expression; face short and flat; muzzle less projecting than in Loris; ears small, rounded, hairy, and nearly buried in the fur; neck short; tail invisible externally. Limbs short; index-finger small, containing three bones; toes remaining spontaneously contracted after death. Top of skull with prominent crests, globular behind; facial bones conspicuously projecting in front; orbits large, their inner margins separated from each other by a narrow flat space. Pre-maxillæ not produced far in front; hind border of bony palate not extending backwards beyond the median molar. Of the upper teeth, the inner incisor larger than the outer, one often absent on each side; canine vertically very long, with a gap between it and the anterior pre-molar; anterior pre-molar elongate, the posterior differing considerably from the anterior molar, and having a short cusped heel behind; posterior molar with a three-cusped crown. Teeth of lower jaw agreeing with those in the diagnosis of the family (suprà, p. 24). Vertebræ in dorsal and lumbar regions together 23 or 24. The long flexor muscle of the thumb, so characteristic of the Anthropoid Apes, is present in Nycticebus. The interlacement of the tendons of the muscles of its foot (according to Huxley and Murie) closely resembles the arrangement in the higher Primates. The long flexor muscle of the toes (flexor longus digitorum) is very large, and has one important origin on the lower end (internal condyle) of the thigh-bone correlated with the powerful grasp of its hind-limbs. The female bears one young at a birth.

Above, ashy-grey, rather paler below; more or less silvery on the back, often rufescent on the rump, with the hairs dark ashy at the roots; dorsal stripe from crown to loins chestnut {35}brown; circle round the eyes dark brown; a white line down the nose between the eyes; oral patch, including the ears, brown.

The Slow-Loris varies greatly in size and colour in the different regions it inhabits, and its varieties have been recognised by many naturalists as distinct species.

Every shade of colour occurs among specimens from different habitats. The colour varies between rufescent grey, or greyish-rufous, or white (with a brown tinge showing through from below) and silvery grey. The dorsal stripe varies from rufous to dull grey or even black, expanding out, or not, on the crown of the head, arms, and cheeks, bifurcating to the orbital rings and ear-patches, or to one or other only. Sometimes the dorsal stripe and face-markings are wanting altogether. Under side varying from pale rufescent grey to light rufous or dull grey. Length of head and body varying from 12¾ to 16 inches.

"It is an interesting fact," observes St. George Mivart, "that as far as concerns the skull and dentition, the Asiatic Nycticebus far more resembles the African Perodicticus than it does its Oriental neighbour Loris."

DISTRIBUTION.--The Slow-Loris has a comparatively wide and interrupted range. It is common in the dense mountain forests of Assam and Burma (where it has received the distinctive appellation of N. bengalensis), as well as in Tenasserim and the Malayan Peninsula. It has also been obtained in Siam and Cochin-China, whence it has been described as a distinct species (N. cinereus), from its silvery-grey fur; while it also occurs--somewhat reduced in size--and often (but not invariably) without the upper incisor teeth--in the islands of Sumatra, Java, and Borneo with its surrounding islet groups, {36}as well as in the Philippine Islands. The form from the last-named localities (figured on Plate III.) has generally been recognised as N. javanicus; but, from a careful examination of the material in the British Museum, it appears to the present writer that the specimens from all these localities merge so insensibly into each other that it is impossible to separate them into distinct species. The Slow-Loris, though occurring on the north-eastern frontier of India, has not yet been discovered in the Himalayas.

HABITS.--Like the Slender Loris, the Slow-Loris is arboreal and nocturnal, hardly differing in its food and general habits from the latter. It lives alone or in pairs, and moves about very slowly, with its head curiously drawn up close to its body, with the latter arched and its limbs very angularly disposed. Colonel Tickell has observed it, however, to raise itself on its hind-legs and throw itself upon an insect. It is generally silent, but can utter a low growl when angry. In captivity it becomes docile, but is never very long-lived. Tickell records that "it never by choice leaves the trees.... It climbs readily and grasps with great tenacity. If placed on the ground, it proceeds, if frightened, in a wavering kind of trot, the limbs placed at right angles. It sleeps rolled up in a ball, its head and hands buried between its thighs, and wakes up in the dusk of the evening to commence its nocturnal rambles." Another observer records: "When he climbs he first lays hold of the branch with one of his hands and then with the other. When he has obtained a firm hold with both hands, he moves one of his hind-paws, and after firmly grasping the branch with it, he moves the other. He never quits his hold with his hind-paws until he has obtained a secure grasp with his hands." The remarkable tenacity of grasp in its feet is largely due to the {37}automatic action of the flexor muscles of the toes (the digits continuing flexed even after death), and the mere extension of the leg largely contributes to the "effortless suspension of the body" (Murie), as in the Fruit-Bats and other species which hang passively by their hind-limbs. (Huxley.)

Dr. Coghlan, speaking of the Chinese race (N. cinereus), says: "They make a curious chattering noise when angry, and when pleased at night they utter a short though tuneful whistle of one unvaried note; this whistle is thought by Chinese sailors, who take them to sea, to denote the coming of wind.... Their intelligence seems to be much below that of the Monkey.... The Slow-Loris, when newly-born, is about four inches long, and covered with fur; it holds on by its four hands to the mother's fur, and in that attitude sucks the milk from its parent's breast."

THE GALAGOS. SUB-FAMILY II. GALAGINÆ.

The Lemurs comprised in the present Sub-family are divisible into two groups--those inhabiting the mainland of Africa and those confined to the island of Madagascar. The exclusively African species, the True Galagos, constitute the single genus Galago; while the Malagasy group is represented by three genera, the so-called Fat-tailed Lemurs (Opolemur), the Dwarf-Lemurs (Microcebus), and the Mouse-Lemurs (Chirogale). The members of this Sub-family vary considerably in size, and are all covered with soft woolly fur. Their ears especially are largely developed, being more or less membranaceous and naked, and their sense of hearing very acute. The eyes are large and the tail always elongated. In the skull the length of the muzzle is less that the greatest longitudinal diameter of the orbit (except in the genus Galago). {38}Their teeth number 36--18 above and 18 below--as in the bulk of the Lemuridæ; the upper molars present on their crown an oblique ridge from the outer hind cusp to the inner front cusp. The ankle region (tarsus) of the hind-limb is much elongated, through the lengthening of two of its bones (the calcaneum and naviculare): this feature occurring to a greater extent among the African than among the Malagasy species. The mammæ are four in number, two on the breast and two on the abdomen.

Many of the species hibernate during the dry winter season, and to enable them to survive, they accumulate during the summer months a thick deposit of fat over their bodies, more especially at the root of the tail, a fact first conspicuously observed in the Opolemurids. This fat is absorbed for their sustenance during their prolonged torpidity.

THE AFRICAN GALAGOS. GENUS GALAGO.

Galago, Geoffr., Mag. Encycl., Ann. 2, i., p. 49 (1796).

The African Galagos are generally larger in size than the Madagascar members of the group, and have the snout produced beyond the lower jaw. Their ears are large, membranaceous, and have a very mobile contractile hinder edge, the animal having the power of folding them up at will. The eyes are also large and approximated; the fingers and toes very long and slender, and the tail thick and bushy.

The skull presents a high, broad, and round brain-case, with a relatively short facial region. The pre-maxillary bones are very much reduced, so that the muzzle, measured from the anterior margin of the orbit forward, is shorter than the longitudinal diameter of the orbits. The bony palate is also relatively short. Compared with those of the Madagascar genera {39}the orbits are, according to Dr. Forsyth Major, much broader vertically and horizontally in the genus Galago. The squamosal region of the skull and the outer portion of the ear-capsules (the periotic) are large and inflated. The mandible (or lower jaw) has its lower hind edge, or angle, produced backward.

The dentition of the Galagos presents several important characters. In respect to their upper teeth, the incisors are small, equal, and have a hind cusp on the cingulum. A distinct gap exists between the canine and the pre-molar teeth. Of the pre-molars, the anterior one is canine-like, and is equally distant from the canine and its own next neighbour. To the outside it has one main cusp, and generally one minute supplementary cusp on each side. The median pre-molar shows three cusps, and one strong inner front cusp. The posterior pre-molar is always molar-like. It has one front supplementary and two main cusps to the outside; and one front and one supplementary hind cusp to the inside: it has also on the crown the oblique ridge spoken of above.

The molars have a deep concavity on their hind border, due to the development of the cingulum on the inner half only of that border of the tooth; to the outside they present two main cusps (and often supplementary minute fore and hind cusps); while to the inside they present two cusps, and also an intermediate cusp in front between the two fore cusps; the oblique ridge is also here present; the hindmost molar is three-cusped. The five hind molars are, therefore, nearly equal in size. In the lower jaw the pre-molars are complicated. The anterior and median are canine-like and procumbent, with a cusped heel behind; the posterior is distinguished from a molar only by the lesser size of its fore-part. The molars are also complicated; the anterior and median are equal in size {40}and four-cusped--the two front cusps (united by a ridge) are taller than the two hind ones, and there is a minute cusp between the two hind cusps. The posterior molar, though smaller than the others, is five-cusped. The oblique ridge is not present in the lower molars.

The brain of the Galagos is narrower and shallower than that in the Lemurinæ.

The female gives birth to two or three young at a time.