The babirusas (from Indonesian bābī rūsa, lit. "deer-hog") are a genus, Babyrousa, in the pig family (Suidae) found in Wallacea, or specifically the Indonesian islands of Sulawesi, Togian, Sula and Buru. All members of this genus were considered part of a single species until 2002, the babirusa, B. babyrussa, but following the split into several species, this scientific name is restricted to the Buru babirusa from Buru and Sula, whereas the best-known species, the north Sulawesi babirusa, is named B. celebensis. If a babirusa does not grind its tusks (achievable through regular activity), they can eventually keep growing so as to penetrate the animal's own skull.
The genus is monotypic within the subfamily Babyrousinae, or alternatively considered to form a tribe, Babyrousini, of the subfamily Suinae. To date, only one fossil skull has been found to suggest a larger ancestor.abirusa are notable for the long upper canines in the males. The upper canines of male babirusa emerge vertically from the alveolar process, penetrating though the skin and curving backward over the front of the face and towards the forehead. The lower canines also grow upwards. The canines of the female are either reduced or absent. The structure of the male’s canines vary by species. In the golden babirusa, the upper canines are short and slender with the alveolar rotated forward to allow the lower canines to cross the lateral view.
From : http://en.wikipedia.org/wiki/Babirusa