The great order of Ungulata is represented by various forms of sheep, as many as ten or twelve wild species of Ovis being met with in the mountain chains of Asia; and more sparingly by several peculiar forms of antelope, such as the saiga (Saiga tatarica), and the Gazella gutturosa, or yellow sheep. Coming to the deer, we also meet with characteristic forms in northern Asia, especially those belonging to the typical genus Cervus.
The true oryx of classical writers was probably the East and North-east African beisa-oryx (Oryx beisa), which is replaced in South Africa by the gemsbuck (oryx gazella).
The antelopes include the beisa oryx, fairly common and widely distributed; the greater and lesser kudu (the greater kudu is not found on the Ogaden plateau); the Somali hartebeest (Bubalis Swaynei), found only in the Haud and Ogo districts; waterbuck, rare except along the Webi Shebeli and the Nogal; the dol or Somali bushbuck; the dibatag or Clarke's gazelle; the giraffe-like gerenuk or Waller's gazelle, very common; the aoul or Soemmering's gazelle, widely distributed; the dero (Gazella Speki); and the small dikdik or sakaro antelope, found in almost every thicket.
Gazelles (Gazella), which form by far the largest genus of the subfamily, are inhabitants of open and frequently more or less desert districts.