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 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 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."