Under _Cobus_, the proper Latin form of Sir Andrew Smith’s term _Kobus_ (taken, no doubt, from the so-called “Kob” Antelope), we follow Flower and Lydekker in uniting the genera _Cobus_, _Adenota_, and _Hydrotragus_ of some authors. The group thus formed contains 11 species which may be arranged in two sections as follows:-- Section I. (_Cobus_). Larger in size; fur grizzled; neck maned. A. Nape uniform with back; horns lunate, inclined forwards. _a._ With a white rump-band 58. _C. ellipsiprymnus_. _b._ Without a white rump-band. _a^1._ Ears shorter, rounded; eye-region not white. _a^2._ General colour rufous 59. _C. unctuosus_. _b^2._ General colour fuliginous. Back lighter 60. _C. crawshayi_. Back darker 61. _C. penricei_. _b^1._ Ears longer, pointed; eye-region white 62. _C. defassa_. B. Nape conspicuously white; horns serpentine, inclined backwards. 63. _C. maria_. Section II. (_Adenota_). Size smaller; fur above uniform rufous; neck not maned. A. Back of ears white 64. _C. leucotis_. B. Back of ears rufous. _a._ Horns shorter, not twice the length of the skull. _a^1._ Fore legs black in front; hair short. Larger; white all round the eye 65. _C. thomasi_. Smaller; white line above the eye 66. _C. kob_. _b^1._ Fore legs uniform rufous; hair long 67. _C. vardoni_. _b._ Horns longer, more than twice the length of the skull; legs in front black 68. _C. lechee_. [Illustration: THE BOOK OF ANTELOPES, PL. XXXII. _J. Smit del & lith._ _Hanhart imp._ The Common Waterbuck. COBUS ELLIPSIPRYMNUS. _Published by R. H. Porter._] 58. THE COMMON WATERBUCK. COBUS ELLIPSIPRYMNUS (OGILBY). [PLATE XXXII.] _Antilope ellipsiprymnus_, =Ogilby=, P. Z. S. 1833, p. 47; =id.= Penny Enc. ii. p. 88 (1834); =Wagn.= Schr. Säug. iv. p. 432 (1843); =id.= op. cit. v. p. 434; =Peters=, Säug. Mossamb. p. 189 (1852) (Zambesia). _Aigocerus ellipsiprymnus_, =Harr.= Wild Anim. S. Afr. p. 71, pl. xiv. (1840); =id.= Wild Sport S. Afr. p. 387 (1838), ed. 5, p. 351 (1852).