Cranium larger in all its parts than in other species. Nasal bones elongated beyond the incisor teeth; nose very flat, this being due to the large air-cavity (called false nose) in the jaw-bone below, connected with the nose. The length and breadth of the muzzle gives a peculiar expression to the face of _P. coronatus_. This species, like the preceding, is subject to considerable variation. The whole head is sometimes grey, washed with rufous; the upper surface and root of the tail white, flushed with rust-colour. In examples living further in the interior than the habitat of the type (Bay of Bembatoka), the back is more rufous, the neck has a large grey or brown patch, and the chest is very dark brownish rust-colour. The abdomen and the inner sides of the limbs are bright red. DISTRIBUTION.--This species occurs on the north-west coast of Madagascar, between the Bay of Mozamba to the north and the River Manjaray on the south, ranging over the country to a considerable distance into the interior. The lighter-coloured specimens come from the more northern range of the species, while the more brightly-marked varieties have been obtained {104}in the interior more to the south. It is curious, remarks M. Grandidier, to find races and species of the same genus so exactly restricted, that one has only to cross a river, not necessarily large, in order to obtain on one bank certain species of _Propithecus_, whereas those occurring on the opposite bank may be of a very distinct species or race. To what influence in their surroundings can all these variations be ascribed? One can understand that species inhabiting a wooded and humid country, or living among granitic mountains (as _P. diadema_ does), would differ in size and fur from other members of the same genus which live in dry and arid plains (as in the case of _P. verreauxi_); but how can the great variations that occur in members of the same species living a few miles, and perhaps only a few metres, apart, be explained, when the external conditions are almost the same?