_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."