Chapter I: The Diademed Sifaka. Propithecus Diadema

_Propithecus diadema_, Bennett, P. Z. S., 1832, p. 20; Milne-Edwards and
Grandid., Hist. Nat. Madag., Mamm., p. 296 (with full synonymy), Atlas,
pl. 1-3.

CHARACTERS.--Fur long, silky, the muzzle naked. Head shorter and rounder than in the other species of the genus; thumb slender, like the toes, set far back, free; great toe very strong, and in the same plane with the other digits; a marked depression exists in the skull behind the orbits. Body, 21 inches; tail, 19 inches in length.

Forehead crossed by a broad white bar; cheeks in front of the ears, and the under side of the chin, white or fulvous white; face black, with a few short black hairs. Back of head, neck, shoulders, sides of body, outer sides of arms, sometimes grey, but generally very dark brown, merging into dark grey on the lower back. Tail at its root washed with orange-yellow, paler in the middle, greyish-white at its extremity. Fore-arm, lower part of arm, sacral region, and external face of hind-limbs, bright {99}orange-yellow. Hands black-haired to the ends of the fingers, but with long and yellow tufts of hair at the tips. Feet pale orange and haired to the nails. Chest dark brown. Under surface white, or white tinged with yellow, or dark brownish-grey. Internal face of the fore-limbs grey, from the intermixture of black hairs; that of the hind-limbs pale yellow.

YOUNG.--Similar in colour to the adults, but lighter; the frontal band yellow, not white; limbs light yellow.

VARIETIES.--Several varieties of this species--the "Simpona" of the natives--have been described, of which the following deserve special notice:--

THE SILKY SIFAKA. PROPITHECUS SERICEUS.

Face black, with flesh-coloured spots; the body entirely white, faintly washed with yellow; the base of the tail washed with rust-red. It is of the same size as the type-form, and appears to be only an albino variety. Specimens showing every gradation in coloration between that of the type and the absolute albino are now well known. This form, however, is more or less restricted to the narrow belts of forest on the eastern side of the mountains in the north-east of Madagascar, between the rivers Lokoi and Bemarivo, a region conterminous with that inhabited by the typical species.

MILNE-EDWARDS' SIFAKA. PROPITHECUS EDWARDSI.

Differs from the true _P. diadema_ in having the face slightly haired between the eyes and on the chin; a patch on each flank rufous-white or orange-yellow, separated by a reddish-black band; a spot at the root of the tail bright rusty-red, and all the rest of body black, washed slightly with rufous. The young are like the parents. This form is also of the {100}same size as the type, but is a melanistic variety, for a series of specimens show every intermediate shade between that here described and the BLACK SIFAKA (_P. holomelas_), which is of an entirely black colour, and inhabits, as has been shown by MM. Milne-Edwards and Grandidier, the same region as _P. edwardsi_.

DISTRIBUTION.--The typical form of the species is confined to the extended region on the east coast of Madagascar lying between the Bay of Antongil on the north, and the River Masora in the south, in the forest-belts on the eastern aspect of the mountains, where rain falls abundantly and the whole region is covered with luxuriant vegetation. Its melanistic variety (_P. edwardsi_) extends south from the Masora as far as the Faraouny river, but it ranges to higher and colder altitudes on the mountains; while its albinistic variety (_P. sericeus_) lives in the somewhat warmer region to the north of Antongil Bay, each being, to south and north respectively, conterminous with the central habitat of the typical form.