This little Gazelle is a recent discovery of Surgeon Lieut.-Col. A. S. G. Jayakar, C.M.Z.S., who has been for many years resident at Muscat in the service of the British Indian Government. Surgeon Jayakar, whose magnificent collections of Muscat fishes are known to all ichthyologists, has during the past years collected and presented to the National Museum several consignments of mammals from this little-known country. Of these Thomas published an account in the ‘Proceedings’ of the Zoological Society for 1894, the most remarkable of them being a new Wild Goat, from the Akhdar Range behind Muscat, which was named _Hemitragus jayakari_ after its discoverer. In 1897 the British Museum received from Surgeon Jayakar another consignment of mammals collected at Muscat within the previous two years. In this last series, besides the Oman specimens which were referable to species already recorded in Thomas’s paper, there were several skins and skulls of the present Gazelle, obtained from the Nejd or Nedsched Desert in the interior of Arabia. Thomas established his _Gazella marica_ upon these examples. In a letter addressed to Thomas, Dr. Jayakar says that four of the “Reem Gazelles” were from the Nejd Desert and one from Dahireh, the north-western district of Oman. “It is probable,” he continues, “that the species extends down to the desert behind Oman, as that is continuous with the Nejd Desert.” Surgeon Jayakar subsequently presented to the Museum a sixth (female) specimen from Aboor near Adam in Oman. The Marica Gazelle is clearly a close relative of the Persian Gazelle, which it seems to represent in Arabia. But it is considerably smaller in size, paler in colour, and is nearly free from face-markings, besides having horns in the female sex. This last point is interesting, as it shows how little importance, in a generic sense, should be attributed to the presence or absence of horns in the female of an Antelope; for it appears that this species, in which the horns are present in the female, is unquestionably more nearly related to one in which the horns are absent in the female than to the group of _Gazella dorcas_, in which the horns are developed in both sexes.