These differences seem to be quite constant, so far as we have materials for comparison, and we therefore think that as the Algerian form has had a name given to it, it may be provisionally retained as a subspecies, at least until these characters are shown to be variable. The accompanying figure, for the use of which we are indebted to the kindness of the Zoological Society, gives a side view of the skull and horns of the Algerian form. [Illustration: Fig. 68. Skull of _Gazella leptoceros loderi_, ♂. (P.Z.S. 1894, p. 471.)] Our representations of this Gazelle (Plate LXIII.) have been prepared by Mr. Smit--that of the male (front figure) from a mounted specimen in the British Museum obtained by Mr. J. I. S. Whitaker in the Tunisian Sahara, and presented by him in 1894; that of the female from the example from Egypt living in the Zoological Society’s Gardens. In the British Museum are likewise the typical skin and horns of _Gazella loderi_ obtained by Sir Edmund Loder in the desert about a hundred miles south of Biskra, some frontlets and horns from Biskra, presented by Mr. Rowland Ward, and a skin and skull of a female from Tunis, presented by Mr. J. I. S. Whitaker along with the male now mounted. The example of _Gazella leptoceros typica_ sent to Sclater by Mr. Birdwood is also now in the National Collection. We have also to thank Dr. J. Anderson, F.Z.S., for the loan of a skin and skull of an old male of the Egyptian form of this Gazelle obtained near the Natron Lakes in Egypt. _May,_ 1898. [Illustration: THE BOOK OF ANTELOPES, PL. LXIV. _Wolf del J Smit lith_ _Hanhart imp._ The Isabella Gazelle. GAZELLA ISABELLA. _Published by R.H. Porter._] 94. THE ISABELLA GAZELLE. GAZELLA ISABELLA, GRAY. [PLATE LXIV.] _Antilope dorcas_, =Licht.= Darst. Säug. pl. v. (1827)? _Gazella dorcas_, =Blanf.= Zool. Abyss, p. 261, pl. i. fig. 1 (1870). _Gazella isabella_, =Gray=, Ann. Mag. N. H. (1) xviii. pp. 214 & 231 (1846); =id.= Knowsl. Men. p. 4 (1850); =id.= P. Z. S. 1850, p. 113; =id.= Cat. Ung. B. M. p. 57 (1852); =Gerr.= Cat. Bones Mamm. B. M. p. 233 (1862); =Fitz. & Heugl.= SB. Wien, liv. pt. 1, p. 591 (1866); =Fitz.= SB. Wien, lix. pt. 1, p. 158 (1869); =Gray=, Cat. Rum. B. M. p. 38 (1872); =id.= Hand-l. Rum. B. M. p. 107 (1873); =Brooke=, P. Z. S. 1873, p. 539; =Huet=, Bull. Soc. Acclim. 1887, p. 65; =W. Scl.= Cat. Mamm. Calc. Mus. ii. p. 157 (1891); =Ward=, Horn Meas. (1) p. 116 (1892), (2) p. 158 (1896). _Antilope isidis_, =Sund.= Pecora, K. Vet.-Ak. Handl. 1845, p. 267 (1847); id. Hornschuch’s Transl., Arch. Skand. Beitr. ii. p. 263; Reprint, p. 83 (1848).