Mr. Selous’s field-notes on this Antelope are accompanied by an excellent coloured figure of the whole animal, and by some drawings of the horns, which, by the kind permission of the Zoological Society, we are enabled to reproduce here (see fig. 35, p. 143). It was until recently supposed that the Poku did not extend its range far north of the Zambesi; but in 1890 Mr. Alfred Sharpe met with it on the Luapula north of Lake Mweru, and says (Pr. R. G. S. n. s. xiv. p. 39) that it is common there, although unknown in the countries bordering on Lake Nyasa. Mr. Sharpe sent home three flat skins and several pairs of horns of this species, which were examined by Sclater (P. Z. S. 1892, p. 98; 1893, p. 728), and says, in his accompanying notes, “I doubt if game can be anywhere more plentiful in Central Africa than in the Mweru and Luapula countries. _Cobus vardoni_ and _C. lechee_ run in enormous herds. These two Antelopes are frequently found together, are much alike in appearance, and are both known by the natives as ‘_Nswala_.’ (The Impala is also called ‘_Nswala_’ by them.) The horns of the Letchwé have a much larger spread than those of Vardon’s Antelope, but at a distance it is difficult to distinguish between the two. The Letchwé has a little black stripe on the fore legs which is not found in Vardon’s Antelope. A noticeable feature about the male Letchwé is that when he runs he puts his head down, laying back the horns. Vardon’s Antelope does not do this.” Mr. Sharpe also met with _C. vardoni_ occasionally near the south end of Lake Tanganyika. In the narrative of his second journey to Lake Mweru in 1892 (Geogr. Journ. i. p. 526) Mr. Sharpe has again noticed the abundance of the Poku in the Mweru swamp along with the Lechee. Our figures of _Cobus vardoni_ (Plate XLI.) were drawn by Mr. Smit from the mounted specimens of both sexes in the British Museum procured by Mr. F. C. Selous at Umparira, on the River Chobe, in 1881. There are skins and skulls in the same collection obtained by Mr. Sharpe and Mr. Crawshay in the district of Lake Mweru. _December, 1896._ 68. THE SENGA KOB. COBUS SENGANUS, SP. N. Similar to _C. vardoni_ in most respects, but very much smaller (height at withers in a female, measured in the flesh, 30½ inches). General colour rather darker than in _C. vardoni_, especially on the head. Ears black, tipped behind for fully one-third of the length, instead of merely at their extreme tip. No white ring above the hoofs. Horns unknown. Skull measurements of the type (♀), not fully adult, although enceinte when killed:--Basal length 8·9 inches, greatest breadth 3·75, orbit to muzzle 5·85. _Hab._ Senga, Upper Loangwa River, W. of the N. end of Lake Nyasa: altitude 2500 feet.