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. II. VERREAUX'S SIFAKA. PROPITHECUS VERREAUXI. _Propithecus verreauxi_, Grandid., Album de l'île de la Réunion, iv., pp. 153-162, pls. 1, 2 (1867); Milne-Edwards and Grandid., Hist. Nat. Madag., Mamm., i., p. 305 (with full synonymy), Atlas, pls. 4, 6, 8. CHARACTERS.--Fur short and woolly; face entirely naked; head longer than broad; a well-marked swelling of the skull between the eyes; the upper incisors sub-equal. Smaller and more robust than _P. diadema_, the head longer, the hair on the limbs shorter, the tail longer. {101}Body yellowish-white; a spot on the top of the head dark brown, sometimes washed with rufous, separated from the face by a white frontal bar. Face black; eyes brownish-yellow; interior of ears black, and naked; a grey patch on the middle of the back; outer aspect of the fore-arms, and hind-legs, ashy-grey; rest of the body white. Hands and feet white. Tail yellowish-white. Length of body, 18 inches; of tail, 22 inches. YOUNG.--Entirely white, with a dark brown spot on the head; the under surface of the body washed with rufous. VARIETIES.--Two well-marked varieties of this species are known, both of which were for many years considered to be distinct species. Continued exploration has, however, now resulted in the accumulation in various museums of a large amount of material from many localities, and this proves that the two forms really belong to but one species. VON DER DECKEN'S SIFAKA. PROPITHECUS DECKENI.