(muzzle, facial markings, and anteorbital glands). At first, he considered it to be a reedbuck, though it appeared unnatural that a reedbuck should occur in the dry sandy plateau of Somalia. Thomas originally considered it a relative of the genus Redunca due to similarities in the morphology of horns, and placed it under the genus Cervicapra. However, after considering further specimens, he placed it under the separate genus Ammodorcas. No subspecies have been identified. The dibatag, which holds its black tail straight up when it is fleeing, gets its common name from the Somali words for 'tail' and 'erect': dabu and tag. The dibatag is also known as Clarke's gazelle, after T. W. H. Clarke, an Australian big game hunter who collected the type specimen. Description The dibatag is a medium-sized antelope with a slim body and long neck and legs. The typical head-and-body length is about . It stands up to about at the shoulder. The male weighs between , whereas the female ranges from . The long dark tail ends in a rounded but indistinct tassel. The tail is nearly long. The curved horns, resembling those of reedbuck, are present only on males, with the pointing tips facing forward. The length of horns is typically between , though Rowland Ward recorded a length of from Somalia. This antelope is sexually dimorphic, because females tend to be smaller than males and lack horns. The species has a small, flat, pointed, wedge-shaped head with large eyes and medium-sized ears. A similarity to the gazelles is the black, branched structure in the interior of the ears. The mouth is very small and the upper lip slightly elongated. There are strong facial markings resembling those of a gazelle. A chestnut brown streak runs from the crown up to the nostrils along the nose, flanked on both sides by parallel white stripes that circle the eyes. A white spot marks the throat. The soft and smooth coat is gray to fawn in the upper parts. The ventral side, rump and the insides of the legs are completely white, and the flanks and the buttocks are unmarked. The dibatag closely resembles the gerenuk, with which it is sympatric in eastern and central Somalia and southeastern Ethiopia. Both are brachyodonts and share several facial and cranial features, along with a two-tone coloration of the pelage and strong thick horns (only in males). However, there are